Auto Scale TextView Text to Fit within Bounds

Question

I m looking for an optimal way to resize wrapping text in a TextView so that it will fit within its getHeight and getWidth bounds  I m not simply looking for a way to wrap the text- I want to make sure it both wraps and is small enough to fit entirely on the screen    I ve seen a few cases on StackOverflow where auto resizing was needed  but they are either very special cases with hack solutions  have no solution  or involve re-drawing the TextView recursively until it is small enough  which is memory intense and forces the user to watch the text shrink step-by-step with every recursion     But I m sure somebody out there has found a good solution that doesn t involve what I m doing  writing several heavy routines that parse and measure the text  resize the text  and repeat until a suitably small size has been found    What routines does TextView use to wrap the text  Couldn t those be somehow used to predict whether text will be small enough   tl dr  is there a best-practice way to auto-resize a TextView to fit  wrapped  in its getHeight and getWidth bounds

User · Answer

AppcompatTextView now supports auto sizing starting from Support Library 26 0  TextView in Android O also works same way  More info can be found here  A simple demo app can be found here    lt LinearLayout       xmlns android  http   schemas android com apk res android        xmlns app  http   schemas android com apk res-auto        android layout width  match parent        android layout height  wrap content  gt          lt TextView         android layout width  wrap content          android layout height  wrap content          app autoSizeTextType  uniform          app autoSizeMinTextSize  12sp          app autoSizeMaxTextSize  100sp          app autoSizeStepGranularity  2sp          gt    lt  LinearLayout gt

User · Answer

I have use code from chase and M-WaJeEh and I found some advantage  amp  disadvantage here  from chase     Advantage           it s perfect for 1 line TextView          Disadvantage           if it s more than 1 line with custom font some of text will disappear   if it s enable ellipse  it didn t prepare space for ellipse   if it s custom font  typeface   it didn t support      from M-WaJeEh     Advantage           it s perfect for multi-line         Disadvantage           if set height as wrap-content  this code will start from minimum size and it will reduce to smallest as it can  not from the setSize and reduce by the limited width   if it s custom font  typeface   it didn t support

User · Answer

I started with Chase s AutoResizeTextView class  and made a minor change so it would fit both vertically and horizontally   I also discovered a bug which causes a Null Pointer Exception in the Layout Editor  in Eclipse  under some rather obscure conditions   Change 1   Fit the text both vertically and horizontally  Chase s original version reduces the text size until it fits vertically  but allows the text to be wider than the target   In my case  I needed the text to fit a specified width   This change makes it resize until the text fits both vertically and horizontally   In resizeText int int  change from      Get the required text height int textHeight   getTextHeight text  textPaint  width  targetTextSize       Until we either fit within our text view or we had reached our min text size  incrementally try smaller sizes while textHeight  gt  height  amp  amp  targetTextSize  gt  mMinTextSize        targetTextSize   Math max targetTextSize - 2  mMinTextSize       textHeight   getTextHeight text  textPaint  width  targetTextSize           to      Get the required text height int textHeight   getTextHeight text  textPaint  width  targetTextSize   int textWidth    getTextWidth text  textPaint  width  targetTextSize       Until we either fit within our text view or we had reached our min text size  incrementally try smaller sizes while   textHeight  gt   height      textWidth  gt   width     amp  amp  targetTextSize  gt  mMinTextSize        targetTextSize   Math max targetTextSize - 2  mMinTextSize       textHeight   getTextHeight text  textPaint  width  targetTextSize       textWidth    getTextWidth text  textPaint  width  targetTextSize           Then  at the end of the file  append the getTextWidth   routine  it s just a slightly modified getTextHeight     It probably would be more efficient to combine them to one routine which returns both height and width      Set the text size of the text paint object and use a static layout to render text off screen before measuring private int getTextWidth CharSequence source  TextPaint paint  int width  float textSize           Update the text paint object     paint setTextSize textSize          Draw using a static layout     StaticLayout layout   new StaticLayout source  paint  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true       layout draw sTextResizeCanvas       return layout getWidth             Change 2   Fix a EmptyStackException in the Eclipse Android Layout Editor  Under rather obscure and very precise conditions  the Layout Editor will fail to display the graphical display of the layout  it will throw an  EmptyStackException  null  exception in com android ide eclipse adt   The conditions required are  - create an AutoResizeTextView widget - create a style for that widget - specify the text item in the style  not in the widget definition    as in   res layout main xml    lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout xmlns android  http   schemas android com apk res android      android layout width  fill parent      android layout height  fill parent      android orientation  vertical   gt        lt com ajw DemoCrashInADT AutoResizeTextView         android id    id resizingText          style   style myTextStyle    gt    lt  LinearLayout gt    res values myStyles xml    lt  xml version  1 0  encoding  utf-8   gt   lt resources gt        lt style name  myTextStyle  parent   android style Widget TextView  gt           lt item name  android layout height  gt wrap content lt  item gt           lt item name  android layout width  gt fill parent lt  item gt           lt item name  android text  gt some message lt  item gt       lt  style gt    lt  resources gt    With these files  selecting the Graphical Layout tab when editing main xml will display             error      EmptyStackException  null     Exception details are logged in Window   Show View   Error Log        instead of the graphical view of the layout   To keep an already too-long story shorter  I tracked this down to the following lines  again in resizeText       If there is a max text size set  use the lesser of that and the default text size float targetTextSize   mMaxTextSize  gt  0   Math min mTextSize  mMaxTextSize    mTextSize    The problem is that under the specific conditions  mTextSize is never initialized  it has the value 0   With the above  targetTextSize is set to zero  as a result of Math min    That zero is passed to getTextHeight    and getTextWidth    as the textSize argument   When it gets to layout draw sTextResizeCanvas   we get the exception   It s more efficient to test if  mTextSize    0  at the beginning of resizeText   rather than testing in getTextHeight   and getTextWidth    testing earlier saves all the intervening work   With these updates  the file  as in my crash-demo test app  is now         from   http   stackoverflow com questions 5033012 auto-scale-textview-text-to-fit-within-bounds        package com ajw DemoCrashInADT   import android content Context  import android graphics Canvas  import android text Layout Alignment  import android text StaticLayout  import android text TextPaint  import android util AttributeSet  import android util TypedValue  import android widget TextView          Text view that auto adjusts text size to fit within the view  If the text    size equals the minimum text size and still does not fit  append with an    ellipsis        2011-10-29 changes by Alan Jay Weiner                   change to fit both vertically and horizontally                     test mTextSize for 0 in resizeText   to fix exception in Layout Editor        author Chase Colburn     since Apr 4  2011     public class AutoResizeTextView extends TextView           Minimum text size for this text view     public static final float MIN TEXT SIZE   20          Interface for resize notifications     public interface OnTextResizeListener           public void onTextResize TextView textView  float oldSize  float newSize                 Off screen canvas for text size rendering     private static final Canvas sTextResizeCanvas   new Canvas            Our ellipse string     private static final String mEllipsis                  Registered resize listener     private OnTextResizeListener mTextResizeListener          Flag for text and or size changes to force a resize     private boolean mNeedsResize   false          Text size that is set from code  This acts as a starting point for        resizing     private float mTextSize          Temporary upper bounds on the starting text size     private float mMaxTextSize   0          Lower bounds for text size     private float mMinTextSize   MIN TEXT SIZE          Text view line spacing multiplier     private float mSpacingMult   1 0f          Text view additional line spacing     private float mSpacingAdd   0 0f          Add ellipsis to text that overflows at the smallest text size     private boolean mAddEllipsis   true           Default constructor override     public AutoResizeTextView Context context            this context  null                  Default constructor when inflating from XML file     public AutoResizeTextView Context context  AttributeSet attrs            this context  attrs  0                  Default constructor override     public AutoResizeTextView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           mTextSize   getTextSize                           When text changes  set the force resize flag to true and reset the text        size               Override     protected void onTextChanged final CharSequence text  final int start              final int before  final int after            mNeedsResize   true             Since this view may be reused  it is good to reset the text size         resetTextSize                           If the text view size changed  set the force resize flag to true              Override     protected void onSizeChanged int w  int h  int oldw  int oldh            if  w    oldw    h    oldh                mNeedsResize   true                                   Register listener to receive resize notifications                param listener             public void setOnResizeListener OnTextResizeListener listener            mTextResizeListener   listener                         Override the set text size to update our internal reference values              Override     public void setTextSize float size            super setTextSize size           mTextSize   getTextSize                           Override the set text size to update our internal reference values              Override     public void setTextSize int unit  float size            super setTextSize unit  size           mTextSize   getTextSize                           Override the set line spacing to update our internal reference values              Override     public void setLineSpacing float add  float mult            super setLineSpacing add  mult           mSpacingMult   mult          mSpacingAdd   add                         Set the upper text size limit and invalidate the view                param maxTextSize             public void setMaxTextSize float maxTextSize            mMaxTextSize   maxTextSize          requestLayout            invalidate                           Return upper text size limit                return             public float getMaxTextSize             return mMaxTextSize                         Set the lower text size limit and invalidate the view                param minTextSize             public void setMinTextSize float minTextSize            mMinTextSize   minTextSize          requestLayout            invalidate                           Return lower text size limit                return             public float getMinTextSize             return mMinTextSize                         Set flag to add ellipsis to text that overflows at the smallest text size                param addEllipsis             public void setAddEllipsis boolean addEllipsis            mAddEllipsis   addEllipsis                         Return flag to add ellipsis to text that overflows at the smallest text        size                return             public boolean getAddEllipsis             return mAddEllipsis                         Reset the text to the original size             public void resetTextSize             super setTextSize TypedValue COMPLEX UNIT PX  mTextSize           mMaxTextSize   mTextSize                         Resize text after measuring              Override     protected void onLayout boolean changed  int left  int top  int right  int bottom            if  changed    mNeedsResize                int widthLimit    right - left  - getCompoundPaddingLeft                       - getCompoundPaddingRight                int heightLimit    bottom - top  - getCompoundPaddingBottom                       - getCompoundPaddingTop                resizeText widthLimit  heightLimit                     super onLayout changed  left  top  right  bottom                          Resize the text size with default width and height             public void resizeText             int heightLimit   getHeight   - getPaddingBottom   - getPaddingTop            int widthLimit   getWidth   - getPaddingLeft   - getPaddingRight            resizeText widthLimit  heightLimit                          Resize the text size with specified width and height                param width         param height             public void resizeText int width  int height            CharSequence text   getText               Do not resize if the view does not have dimensions or there is no            text            or if mTextSize has not been initialized         if  text    null    text length      0    height  lt   0    width  lt   0                    mTextSize    0                return                        Get the text view s paint object         TextPaint textPaint   getPaint                Store the current text size         float oldTextSize   textPaint getTextSize                If there is a max text size set  use the lesser of that and the            default text size         float targetTextSize   mMaxTextSize  gt  0   Math min mTextSize  mMaxTextSize                    mTextSize              Get the required text height         int textHeight   getTextHeight text  textPaint  width  targetTextSize           int textWidth   getTextWidth text  textPaint  width  targetTextSize               Until we either fit within our text view or we had reached our min            text size  incrementally try smaller sizes         while    textHeight  gt  height      textWidth  gt  width                    amp  amp  targetTextSize  gt  mMinTextSize                targetTextSize   Math max targetTextSize - 2  mMinTextSize               textHeight   getTextHeight text  textPaint  width  targetTextSize               textWidth   getTextWidth text  textPaint  width  targetTextSize                         If we had reached our minimum text size and still don t fit  append            an ellipsis         if  mAddEllipsis  amp  amp  targetTextSize    mMinTextSize  amp  amp  textHeight  gt  height                   Draw using a static layout             StaticLayout layout   new StaticLayout text  textPaint  width                      Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  false               layout draw sTextResizeCanvas               int lastLine   layout getLineForVertical height  - 1              int start   layout getLineStart lastLine               int end   layout getLineEnd lastLine               float lineWidth   layout getLineWidth lastLine               float ellipseWidth   textPaint measureText mEllipsis                   Trim characters off until we have enough room to draw the                ellipsis             while  width  lt  lineWidth   ellipseWidth                    lineWidth   textPaint measureText text subSequence start  --end   1                           toString                               setText text subSequence 0  end    mEllipsis                          Some devices try to auto adjust line spacing  so force default line            spacing            and invalidate the layout as a side effect         textPaint setTextSize targetTextSize           setLineSpacing mSpacingAdd  mSpacingMult               Notify the listener if registered         if  mTextResizeListener    null                mTextResizeListener onTextResize this  oldTextSize  targetTextSize                         Reset force resize flag         mNeedsResize   false                 Set the text size of the text paint object and use a static layout to        render text off screen before measuring     private int getTextHeight CharSequence source  TextPaint paint  int width              float textSize               Update the text paint object         paint setTextSize textSize              Draw using a static layout         StaticLayout layout   new StaticLayout source  paint  width                  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true           layout draw sTextResizeCanvas           return layout getHeight                   Set the text size of the text paint object and use a static layout to        render text off screen before measuring     private int getTextWidth CharSequence source  TextPaint paint  int width              float textSize               Update the text paint object         paint setTextSize textSize              Draw using a static layout         StaticLayout layout   new StaticLayout source  paint  width                  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true           layout draw sTextResizeCanvas           return layout getWidth                 A big thank you to Chase for posting the initial code   I enjoyed reading through it to see how it worked  and I m pleased to be able to add to it

User · Answer

My implementation is a bit more complex  but comes with the following goodies    takes the available width and available height into account works with single line and multiline labels uses ellipsis in case the minimum font size is hit since the internal text representation is changed  remembers the originally set text in a separate variable ensures that the canvas is always only as big as it needs to be  while it uses all the available height of the parent          Text view that auto adjusts text size to fit within the view  If the text    size equals the minimum text size and still does not fit  append with an    ellipsis         Based on the original work from Chase Colburn     amp lt http   stackoverflow com a 5535672 305532 gt         author Thomas Keller  amp lt me thomaskeller biz gt      public class AutoResizeTextView extends TextView           in dip     private static final int MIN TEXT SIZE   20       private static final boolean SHRINK TEXT SIZE   true       private static final char ELLIPSIS     u2026        private static final float LINE SPACING MULTIPLIER MULTILINE   0 8f       private static final float LINE SPACING MULTIPLIER SINGLELINE   1f       private static final float LINE SPACING EXTRA   0 0f       private CharSequence mOriginalText          temporary upper bounds on the starting text size     private float mMaxTextSize          lower bounds for text size     private float mMinTextSize          determines whether we re currently in the process of measuring ourselves         so we do not enter onMeasure recursively     private boolean mInMeasure   false          if the text size should be shrinked or if the text size should be kept        constant and only characters should be removed to hit the boundaries     private boolean mShrinkTextSize       public AutoResizeTextView Context context            this context  null           init context  null              public AutoResizeTextView Context context  AttributeSet attrs            this context  attrs  0           init context  attrs              public AutoResizeTextView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           init context  attrs              private void init Context context  AttributeSet attrs               the current text size is used as maximum text size we can apply to            our widget         mMaxTextSize   getTextSize            if  attrs    null                TypedArray a   context obtainStyledAttributes attrs  R styleable AutoResizeTextView               mMinTextSize   a getFloat R styleable AutoResizeTextView minFontSize  MIN TEXT SIZE               mShrinkTextSize   a getBoolean R styleable AutoResizeTextView shrinkTextSize  SHRINK TEXT SIZE               a recycle                          Override     public void setTextSize float size            mMaxTextSize   size          super setTextSize size                         Returns the original  unmodified text of this widget                 return             public CharSequence getOriginalText                text has not been resized yet         if  mOriginalText    null                return getText                      return mOriginalText              Override     public void setText CharSequence text  BufferType type            if   mInMeasure                mOriginalText   text toString                      super setText text  type               SuppressLint  DrawAllocation        Override     protected void onMeasure int widthMeasureSpec  int heightMeasureSpec            mInMeasure   true          try               int availableWidth   MeasureSpec getSize widthMeasureSpec  - getCompoundPaddingLeft                       - getCompoundPaddingRight                int availableHeight   MeasureSpec getSize heightMeasureSpec  - getCompoundPaddingTop                       - getCompoundPaddingBottom                    Do not resize if the view does not have dimensions or there is no                text             if  mOriginalText    null    mOriginalText length      0    availableWidth  lt   0                    return                             TextPaint textPaint   getPaint                    start with the recorded max text size             float targetTextSize   mMaxTextSize              String originalText   mOriginalText toString                String finalText   originalText               Rect textSize   getTextSize originalText  textPaint  targetTextSize               boolean textExceedsBounds   textSize height    gt  availableHeight    textSize width    gt  availableWidth              if  mShrinkTextSize  amp  amp  textExceedsBounds                       check whether all lines can be rendered in the available                    width   height without violating the bounds of the parent and                    without using a text size that is smaller than the minimum                    text size                 float heightMultiplier   availableHeight    float  textSize height                    float widthMultiplier   availableWidth    float  textSize width                    float multiplier   Math min heightMultiplier  widthMultiplier                   targetTextSize   Math max targetTextSize   multiplier  mMinTextSize                       measure again                 textSize   getTextSize finalText  textPaint  targetTextSize                                 we cannot shrink the height further when we hit the available                height  but we can shrink the width by applying an ellipsis on                each line             if  textSize width    gt  availableWidth                    StringBuilder modifiedText   new StringBuilder                    String lines     originalText split System getProperty  line separator                     for  int i   0  i  lt  lines length  i                          modifiedText append resizeLine textPaint  lines i   availableWidth                           add the separator back to all but the last processed line                     if  i    lines length - 1                            modifiedText append System getProperty  line separator                                                             finalText   modifiedText toString                        measure again                 textSize   getTextSize finalText  textPaint  targetTextSize                              textPaint setTextSize targetTextSize               boolean isMultiline   finalText indexOf   n    gt  -1                 do not include extra font padding  for accents       for                multiline texts  this will prevent proper placement with                Gravity CENTER VERTICAL             if  isMultiline                    setLineSpacing LINE SPACING EXTRA  LINE SPACING MULTIPLIER MULTILINE                   setIncludeFontPadding false                 else                   setLineSpacing LINE SPACING EXTRA  LINE SPACING MULTIPLIER SINGLELINE                   setIncludeFontPadding true                                 according to                 lt http   code google com p android issues detail id 22493 gt                 we have to add a unicode character to trigger the text centering                in ICS  this particular character is known as  zero-width  and                does no harm              setText finalText     u200B                 int measuredWidth   textSize width     getCompoundPaddingLeft     getCompoundPaddingRight                int measuredHeight   textSize height     getCompoundPaddingTop     getCompoundPaddingBottom                    expand the view to the parent s height in case it is smaller or                to the minimum height that has been set                FIXME  honor the vertical measure mode  EXACTLY vs AT MOST  here                somehow             measuredHeight   Math max measuredHeight  MeasureSpec getSize heightMeasureSpec                setMeasuredDimension measuredWidth  measuredHeight             finally               mInMeasure   false                       private Rect getTextSize String text  TextPaint textPaint  float textSize            textPaint setTextSize textSize              StaticLayout depends on a given width in which it should lay out the            text  and optionally also split into separate lines              Therefor we calculate the current text width manually and start with            a fake  read  maxmimum  width for the height calculation             We do  not  use layout getLineWidth   here since this returns            slightly smaller numbers and therefor would lead to exceeded text box            drawing          StaticLayout layout   new StaticLayout text  textPaint  Integer MAX VALUE  Alignment ALIGN NORMAL  1f  0f  true           int textWidth   0          String lines     text split System getProperty  line separator             for  int i   0  i  lt  lines length    i                textWidth   Math max textWidth  measureTextWidth textPaint  lines i                       return new Rect 0  0  textWidth  layout getHeight                private String resizeLine TextPaint textPaint  String line  int availableWidth            checkArgument line    null  amp  amp  line length    gt  0   expected non-empty string            int textWidth   measureTextWidth textPaint  line           int lastDeletePos   -1          StringBuilder builder   new StringBuilder line           while  textWidth  gt  availableWidth  amp  amp  builder length    gt  0                lastDeletePos   builder length     2              builder deleteCharAt builder length     2                  don t forget to measure the ellipsis character as well  it                doesn t matter where it is located in the line  it just has to be                there  since there are no  known  ligatures that use this glyph             String textToMeasure   builder toString     ELLIPSIS              textWidth   measureTextWidth textPaint  textToMeasure                     if  lastDeletePos  gt  -1                builder insert lastDeletePos  ELLIPSIS                     return builder toString                  there are several methods in Android to determine the text width  namely        getBounds   and measureText           The latter works for us the best as it gives us the best   nearest        results without that our text canvas needs to wrap its text later on        again      private int measureTextWidth TextPaint textPaint  String line            return Math round textPaint measureText line               revised on 2012-11-21    fixed the placement of the ellipsis  off-by-one error  reworked text size calculation  now always the full text including line breaks is measured  to fix problems when the addition of the height of two single measured lines just didn t lead to the same result as the measurement of the height of the text as a whole instead of looping to find the smallest available text size  just calculate it after the first measurement

User · Answer

A workaround for Android 4 x  I found AutoResizeTextView and it works great on my Android 2 1 emulator  I loved it so much  But unfortunately it failed on my own 4 0 4 cellphone and 4 1 emulator  After trying I found it could be easily resolved by adding following attributes in AutoResizeTextView class in the xml   android ellipsize  quot none quot  android singleLine  quot true quot   With the 2 lines above  now AutoResizeTextView working perfectly on my 2 1  amp  4 1 emulators and my own 4 0 4 cellphone now  Hope this helps you   -

User · Answer

If anyone needs it  here is the same code snippet but for Xamarin Android                        DO WHAT YOU WANT TO PUBLIC LICENSE                       Version 1  December 2017        Copyright  C  2017 Nathan Westfall        Everyone is permitted to copy and distribute verbatim or modified    copies of this license document  and changing it is allowed as long    as the name is changed                    DO WHAT YOU WANT TO PUBLIC LICENSE      TERMS AND CONDITIONS FOR COPYING  DISTRIBUTION AND MODIFICATION         0  You just DO WHAT YOU WANT TO       using Android Content  using Android Runtime  using Android Widget  using Android Util  using Android Text   using Java Lang   namespace My Text       public class AutoResizeTextView   TextView               public const float MIN TEXT SIZE   20           public interface OnTextResizeListener                       void OnTextResize TextView textView  float oldSize  float newSize                      private const string mEllipsis                   private OnTextResizeListener mTextResizeListener           private bool mNeedsResize   false           private float mTextSize           private float mMaxTextSize   0           private float mMinTextSize   MIN TEXT SIZE           private float mSpacingMult   1 0f           private float mSpacingAdd   0 0f           public bool AddEllipsis   get  set      true           public AutoResizeTextView Context context    this context  null               public AutoResizeTextView Context context  IAttributeSet attrs    this context  attrs  0               public AutoResizeTextView Context context  IAttributeSet attrs  int defStyle   base context  attrs  defStyle                        mTextSize   TextSize                     protected override void OnTextChanged ICharSequence text  int start  int lengthBefore  int lengthAfter                        base OnTextChanged text  start  lengthBefore  lengthAfter                mNeedsResize   true               ResetTextSize                       protected override void OnSizeChanged int w  int h  int oldw  int oldh                        base OnSizeChanged w  h  oldw  oldh                if  w    oldw    h    oldh                  mNeedsResize   true                     public void SetOnResizeListener OnTextResizeListener listener                        mTextResizeListener   listener                     public override void SetTextSize  GeneratedEnum  ComplexUnitType unit  float size                        base SetTextSize unit  size                mTextSize   TextSize                     public override void SetLineSpacing float add  float mult                        base SetLineSpacing add  mult                mSpacingMult   mult              mSpacingAdd   add                     public void SetMaxTextSize float maxTextSize                        mMaxTextSize   maxTextSize              RequestLayout                Invalidate                       public float GetMaxTextSize                         return mMaxTextSize                     public void SetMinTextSize float minTextSize                        mMinTextSize   minTextSize              RequestLayout                Invalidate                       public float GetMinTextSize                         return mMinTextSize                     public void ResetTextSize                         if mTextSize  gt  0                                base SetTextSize ComplexUnitType Px  mTextSize                   mMaxTextSize   mTextSize                                   protected override void OnLayout bool changed  int left  int top  int right  int bottom                        if changed    mNeedsResize                                int widthLimit    right - left  - CompoundPaddingLeft - CompoundPaddingRight                  int heightLimit    bottom - top  - CompoundPaddingBottom - CompoundPaddingTop                  ResizeText widthLimit  heightLimit                             base OnLayout changed  left  top  right  bottom                base OnLayout changed  left  top  right  bottom                      public void ResizeText                         int heightLimit   Height - PaddingBottom - PaddingTop              int widthLimit   Width - PaddingLeft - PaddingRight              ResizeText widthLimit  heightLimit                      public void ResizeText int width  int height                        var text   TextFormatted              if  text    null    text Length      0    height  lt   0    width  lt   0    mTextSize    0                  return               if  TransformationMethod    null                  text   TransformationMethod GetTransformationFormatted TextFormatted  this                TextPaint textPaint   Paint               float oldTextSize   textPaint TextSize              float targetTextSize   mMaxTextSize  gt  0   System Math Min mTextSize  mMaxTextSize    mTextSize               int textHeight   GetTextHeight text  textPaint  width  targetTextSize                while textHeight  gt  height  amp  amp  targetTextSize  gt  mMinTextSize                                targetTextSize   System Math Max targetTextSize - 2  mMinTextSize                   textHeight   GetTextHeight text  textPaint  width  targetTextSize                              if AddEllipsis  amp  amp  targetTextSize    mMinTextSize  amp  amp  textHeight  gt  height                                TextPaint paint   new TextPaint textPaint                    StaticLayout layout   new StaticLayout text  paint  width  Layout Alignment AlignNormal  mSpacingMult  mSpacingAdd  false                   if layout LineCount  gt  0                                        int lastLine   layout GetLineForVertical height  - 1                      if  lastLine  lt  0                          SetText     BufferType Normal                       else                                               int start   layout GetLineStart lastLine                           int end   layout GetLineEnd lastLine                           float lineWidth   layout GetLineWidth lastLine                           float ellipseWidth   textPaint MeasureText mEllipsis                            while  width  lt  lineWidth   ellipseWidth                              lineWidth   textPaint MeasureText text SubSequence start  --end   1  ToString                             SetText text SubSequence 0  end    mEllipsis  BufferType Normal                                                                      SetTextSize ComplexUnitType Px  targetTextSize               SetLineSpacing mSpacingAdd  mSpacingMult                mTextResizeListener  OnTextResize this  oldTextSize  targetTextSize                mNeedsResize   false                     private int GetTextHeight ICharSequence source  TextPaint paint  int width  float textSize                        TextPaint paintCopy   new TextPaint paint               paintCopy TextSize   textSize              StaticLayout layout   new StaticLayout source  paintCopy  width  Layout Alignment AlignNormal  mSpacingMult  mSpacingAdd  false               return layout Height

User · Answer

My need was to resize text in order to perfectly fit view bounds  Chase s solution only reduces text size  this one enlarges also the text if there is enough space   To make all fast  amp  precise i used a bisection method instead of an iterative while  as you can see in resizeText   method  That s why you have also a MAX TEXT SIZE option  I also included onoelle s tips   Tested on Android 4 4                       DO WHAT YOU WANT TO PUBLIC LICENSE                       Version 2  December 2004       Copyright  C  2004 Sam Hocevar  lt sam hocevar net gt        Everyone is permitted to copy and distribute verbatim or modified    copies of this license document  and changing it is allowed as long    as the name is changed                   DO WHAT YOU WANT TO PUBLIC LICENSE      TERMS AND CONDITIONS FOR COPYING  DISTRIBUTION AND MODIFICATION        0  You just DO WHAT YOU WANT TO       import android content Context  import android text Layout Alignment  import android text StaticLayout  import android text TextPaint  import android util AttributeSet  import android util TypedValue  import android widget TextView          Text view that auto adjusts text size to fit within the view     If the text size equals the minimum text size and still does not    fit  append with an ellipsis         author Chase Colburn     since Apr 4  2011     public class AutoResizeTextView extends TextView           Minimum text size for this text view     public static final float MIN TEXT SIZE   26          Maximum text size for this text view     public static final float MAX TEXT SIZE   128       private static final int BISECTION LOOP WATCH DOG   30          Interface for resize notifications     public interface OnTextResizeListener           public void onTextResize TextView textView  float oldSize  float newSize                 Our ellipse string     private static final String mEllipsis                  Registered resize listener     private OnTextResizeListener mTextResizeListener          Flag for text and or size changes to force a resize     private boolean mNeedsResize   false          Text size that is set from code  This acts as a starting point for resizing     private float mTextSize          Temporary upper bounds on the starting text size     private float mMaxTextSize   MAX TEXT SIZE          Lower bounds for text size     private float mMinTextSize   MIN TEXT SIZE          Text view line spacing multiplier     private float mSpacingMult   1 0f          Text view additional line spacing     private float mSpacingAdd   0 0f          Add ellipsis to text that overflows at the smallest text size     private boolean mAddEllipsis   true          Default constructor override     public AutoResizeTextView Context context            this context  null                 Default constructor when inflating from XML file     public AutoResizeTextView Context context  AttributeSet attrs            this context  attrs  0                 Default constructor override     public AutoResizeTextView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           mTextSize   getTextSize                          When text changes  set the force resize flag to true and reset the text size               Override     protected void onTextChanged final CharSequence text  final int start  final int before  final int after            mNeedsResize   true             Since this view may be reused  it is good to reset the text size         resetTextSize                          If the text view size changed  set the force resize flag to true              Override     protected void onSizeChanged int w  int h  int oldw  int oldh            if  w    oldw    h    oldh                mNeedsResize   true                                  Register listener to receive resize notifications         param listener             public void setOnResizeListener OnTextResizeListener listener            mTextResizeListener   listener                        Override the set text size to update our internal reference values              Override     public void setTextSize float size            super setTextSize size           mTextSize   getTextSize                          Override the set text size to update our internal reference values              Override     public void setTextSize int unit  float size            super setTextSize unit  size           mTextSize   getTextSize                          Override the set line spacing to update our internal reference values              Override     public void setLineSpacing float add  float mult            super setLineSpacing add  mult           mSpacingMult   mult          mSpacingAdd   add                        Set the upper text size limit and invalidate the view         param maxTextSize             public void setMaxTextSize float maxTextSize            mMaxTextSize   maxTextSize          requestLayout            invalidate                          Return upper text size limit         return             public float getMaxTextSize             return mMaxTextSize                        Set the lower text size limit and invalidate the view         param minTextSize             public void setMinTextSize float minTextSize            mMinTextSize   minTextSize          requestLayout            invalidate                          Return lower text size limit         return             public float getMinTextSize             return mMinTextSize                        Set flag to add ellipsis to text that overflows at the smallest text size         param addEllipsis             public void setAddEllipsis boolean addEllipsis            mAddEllipsis   addEllipsis                        Return flag to add ellipsis to text that overflows at the smallest text size         return             public boolean getAddEllipsis             return mAddEllipsis                        Reset the text to the original size             public void resetTextSize             if mTextSize  gt  0                super setTextSize TypedValue COMPLEX UNIT PX  mTextSize                 mMaxTextSize   mTextSize                                  Resize text after measuring              Override     protected void onLayout boolean changed  int left  int top  int right  int bottom            if changed    mNeedsResize                int widthLimit    right - left  - getCompoundPaddingLeft   - getCompoundPaddingRight                int heightLimit    bottom - top  - getCompoundPaddingBottom   - getCompoundPaddingTop                resizeText widthLimit  heightLimit                     super onLayout changed  left  top  right  bottom                          Resize the text size with default width and height             public void resizeText             int heightLimit   getHeight   - getPaddingBottom   - getPaddingTop            int widthLimit   getWidth   - getPaddingLeft   - getPaddingRight            resizeText widthLimit  heightLimit                         Resize the text size with specified width and height         param width         param height             public void resizeText int width  int height            CharSequence text   getText               Do not resize if the view does not have dimensions or there is no text         if text    null    text length      0    height  lt   0    width  lt   0    mTextSize    0                return                        Get the text view s paint object         TextPaint textPaint   getPaint                Store the current text size         float oldTextSize   textPaint getTextSize                Bisection method  fast  amp  precise         float lower   mMinTextSize          float upper   mMaxTextSize          int loop counter 1          float targetTextSize    lower upper  2          int textHeight   getTextHeight text  textPaint  width  targetTextSize           while loop counter  lt  BISECTION LOOP WATCH DOG  amp  amp  upper - lower  gt  1                targetTextSize    lower upper  2              textHeight   getTextHeight text  textPaint  width  targetTextSize               if textHeight  gt  height                  upper   targetTextSize              else                 lower   targetTextSize              loop counter                       targetTextSize   lower          textHeight   getTextHeight text  textPaint  width  targetTextSize               If we had reached our minimum text size and still don t fit  append an ellipsis         if mAddEllipsis  amp  amp  targetTextSize    mMinTextSize  amp  amp  textHeight  gt  height                   Draw using a static layout                modified  use a copy of TextPaint for measuring             TextPaint paintCopy   new TextPaint textPaint               paintCopy setTextSize targetTextSize               StaticLayout layout   new StaticLayout text  paintCopy  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  false                  Check that we have a least one line of rendered text             if layout getLineCount    gt  0                       Since the line at the specific vertical position would be cut off                     we must trim up to the previous line                 int lastLine   layout getLineForVertical height  - 1                     If the text would not even fit on a single line  clear it                 if lastLine  lt  0                        setText                                           Otherwise  trim to the previous line and add an ellipsis                 else                       int start   layout getLineStart lastLine                       int end   layout getLineEnd lastLine                       float lineWidth   layout getLineWidth lastLine                       float ellipseWidth   paintCopy measureText mEllipsis                           Trim characters off until we have enough room to draw the ellipsis                     while width  lt  lineWidth   ellipseWidth                            lineWidth   paintCopy measureText text subSequence start  --end   1  toString                                               setText text subSequence 0  end    mEllipsis                                                         Some devices try to auto adjust line spacing  so force default line spacing            and invalidate the layout as a side effect         setTextSize TypedValue COMPLEX UNIT PX  targetTextSize           setLineSpacing mSpacingAdd  mSpacingMult               Notify the listener if registered         if mTextResizeListener    null                mTextResizeListener onTextResize this  oldTextSize  targetTextSize                         Reset force resize flag         mNeedsResize   false                Set the text size of the text paint object and use a static layout to render text off screen before measuring     private int getTextHeight CharSequence source  TextPaint originalPaint  int width  float textSize               modified  make a copy of the original TextPaint object for measuring             apparently the object gets modified while measuring  see also the            docs for TextView getPaint    which states to access it read-only          TextPaint paint   new TextPaint originalPaint              Update the text paint object         paint setTextSize textSize              Measure using a static layout         StaticLayout layout   new StaticLayout source  paint  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true           return layout getHeight

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The problem is about how to have this feature on Button  For TextView it s easy and works very well by following the official document here     Style xml        lt style name  Widget Button CustomStyle  parent  Widget MaterialComponents Button  gt           lt item name  android minHeight  gt 50dp lt  item gt           lt item name  android maxWidth  gt 300dp lt  item gt           lt item name  android textStyle  gt bold lt  item gt           lt item name  android textSize  gt 16sp lt  item gt           lt item name  backgroundTint  gt  color white lt  item gt           lt item name  cornerRadius  gt 25dp lt  item gt           lt item name  autoSizeTextType  gt uniform lt  item gt           lt item name  autoSizeMinTextSize  gt 10sp lt  item gt           lt item name  autoSizeMaxTextSize  gt 16sp lt  item gt           lt item name  autoSizeStepGranularity  gt 2sp lt  item gt           lt item name  android maxLines  gt 1 lt  item gt           lt item name  android textColor  gt  color colorPrimary lt  item gt           lt item name  android insetTop  gt 0dp lt  item gt           lt item name  android insetBottom  gt 0dp lt  item gt           lt item name  android lineSpacingExtra  gt 4sp lt  item gt           lt item name  android gravity  gt center lt  item gt       lt  style gt    Usage    lt com google android material button MaterialButton             android id    id blah              style   style Widget Button CustomStyle              android layout width  match parent              android layout height  wrap content              android layout marginStart  16dp              android layout marginEnd  16dp              android text  Your long text  to the infinity and beyond    Why not       gt    Result

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This solutions works for us   public class CustomFontButtonTextFit extends CustomFontButton       private final float DECREMENT FACTOR    1f       public CustomFontButtonTextFit Context context            super context              public CustomFontButtonTextFit Context context  AttributeSet attrs            super context  attrs              public CustomFontButtonTextFit Context context  AttributeSet attrs              int defStyle            super context  attrs  defStyle              private synchronized void refitText String text  int textWidth            if  textWidth  gt  0                         float availableWidth   textWidth - this getPaddingLeft                       - this getPaddingRight                 TextPaint tp   getPaint                Rect rect   new Rect                tp getTextBounds text  0  text length    rect               float size   rect width                 while size  gt  availableWidth                                setTextSize  getTextSize   - DECREMENT FACTOR                    tp   getPaint                     tp getTextBounds text  0  text length    rect                   size   rect width                                        Override     protected void onMeasure int widthMeasureSpec  int heightMeasureSpec                 super onMeasure widthMeasureSpec  heightMeasureSpec            int parentWidth   MeasureSpec getSize widthMeasureSpec           int parentHeight   MeasureSpec getSize heightMeasureSpec            refitText this getText   toString    parentWidth            if parentWidth  lt  getSuggestedMinimumWidth                parentWidth   getSuggestedMinimumWidth             if parentHeight  lt  getSuggestedMinimumHeight                parentHeight   getSuggestedMinimumHeight             this setMeasuredDimension parentWidth  parentHeight               Override     protected void onTextChanged final CharSequence text  final int start              final int before  final int after                 super onTextChanged text  start  before  after            refitText text toString    this getWidth                 Override     protected void onSizeChanged int w  int h  int oldw  int oldh                super onSizeChanged w  h  oldw  oldh            if  w    oldw               refitText this getText   toString    w

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I started with Chase s solution  but had to adapt two things before it was working as expected on my device  Galaxy Nexus  Android 4 1     using a copy of TextPaint for measuring layout The documentation for TextView getPaint   states that it should be used read-only  so I made a copy in both places where we use the paint object for measuring      1  in resizeText   if  mAddEllipsis  amp  amp  targetTextSize    mMinTextSize  amp  amp  textHeight  gt  height         Draw using a static layout      modified  use a copy of TextPaint for measuring   TextPaint paint   new TextPaint textPaint       2  in getTextHeight   private int getTextHeight CharSequence source  TextPaint originalPaint  int width  float textSize         modified  make a copy of the original TextPaint object for measuring       apparently the object gets modified while measuring  see also the      docs for TextView getPaint    which states to access it read-only    TextPaint paint   new TextPaint originalPaint        Update the text paint object   paint setTextSize textSize          adding a unit to setting the text size     modified  setting text size via this setTextSize  instead of textPaint setTextSize targetTextSize   setTextSize TypedValue COMPLEX UNIT PX  targetTextSize   setLineSpacing mSpacingAdd  mSpacingMult      With these two modifications the solution is working perfectly for me  thanks Chase  I don t know whether it is due to Android 4 x that the original solution was not working  In case you want to see it in action or test whether it really works on your device  you can have a look at my flashcard app Flashcards ToGo where I use this solution to scale the text of a flashcard  The text can have arbitrary length  and the flashcards are displayed in different activities  sometimes smaller sometimes bigger  plus in landscape   portrait mode  and I haven t found any corner case where the solution would not work properly

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As a mobile developer  I was sad to find nothing native that supports auto resizing  My searches did not turn up anything that worked for me and in the end  I spent the better half of my weekend and created my own auto resize text view  I will post the code here and hopefully it will be useful for someone else    This class uses a static layout with the text paint of the original text view to measure the height  From there  I step down by 2 font pixels and remeasure until I have a size that fits  At the end  if the text still does not fit  I append an ellipsis  I had requirements to animate the text and reuse views and this seems to work well on the devices I have and seems to run fast enough for me                         DO WHAT YOU WANT TO PUBLIC LICENSE                       Version 2  December 2004        Copyright  C  2004 Sam Hocevar  lt sam hocevar net gt         Everyone is permitted to copy and distribute verbatim or modified    copies of this license document  and changing it is allowed as long    as the name is changed                    DO WHAT YOU WANT TO PUBLIC LICENSE      TERMS AND CONDITIONS FOR COPYING  DISTRIBUTION AND MODIFICATION         0  You just DO WHAT YOU WANT TO       import android content Context  import android text Layout Alignment  import android text StaticLayout  import android text TextPaint  import android util AttributeSet  import android util TypedValue  import android widget TextView          Text view that auto adjusts text size to fit within the view     If the text size equals the minimum text size and still does not    fit  append with an ellipsis          author Chase Colburn     since Apr 4  2011     public class AutoResizeTextView extends TextView           Minimum text size for this text view     public static final float MIN TEXT SIZE   20          Interface for resize notifications     public interface OnTextResizeListener           public void onTextResize TextView textView  float oldSize  float newSize                 Our ellipse string     private static final String mEllipsis                  Registered resize listener     private OnTextResizeListener mTextResizeListener          Flag for text and or size changes to force a resize     private boolean mNeedsResize   false          Text size that is set from code  This acts as a starting point for resizing     private float mTextSize          Temporary upper bounds on the starting text size     private float mMaxTextSize   0          Lower bounds for text size     private float mMinTextSize   MIN TEXT SIZE          Text view line spacing multiplier     private float mSpacingMult   1 0f          Text view additional line spacing     private float mSpacingAdd   0 0f          Add ellipsis to text that overflows at the smallest text size     private boolean mAddEllipsis   true          Default constructor override     public AutoResizeTextView Context context            this context  null                 Default constructor when inflating from XML file     public AutoResizeTextView Context context  AttributeSet attrs            this context  attrs  0                 Default constructor override     public AutoResizeTextView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           mTextSize   getTextSize                          When text changes  set the force resize flag to true and reset the text size               Override     protected void onTextChanged final CharSequence text  final int start  final int before  final int after            mNeedsResize   true             Since this view may be reused  it is good to reset the text size         resetTextSize                          If the text view size changed  set the force resize flag to true              Override     protected void onSizeChanged int w  int h  int oldw  int oldh            if  w    oldw    h    oldh                mNeedsResize   true                                  Register listener to receive resize notifications         param listener             public void setOnResizeListener OnTextResizeListener listener            mTextResizeListener   listener                        Override the set text size to update our internal reference values              Override     public void setTextSize float size            super setTextSize size           mTextSize   getTextSize                          Override the set text size to update our internal reference values              Override     public void setTextSize int unit  float size            super setTextSize unit  size           mTextSize   getTextSize                          Override the set line spacing to update our internal reference values              Override     public void setLineSpacing float add  float mult            super setLineSpacing add  mult           mSpacingMult   mult          mSpacingAdd   add                        Set the upper text size limit and invalidate the view         param maxTextSize             public void setMaxTextSize float maxTextSize            mMaxTextSize   maxTextSize          requestLayout            invalidate                          Return upper text size limit         return             public float getMaxTextSize             return mMaxTextSize                        Set the lower text size limit and invalidate the view         param minTextSize             public void setMinTextSize float minTextSize            mMinTextSize   minTextSize          requestLayout            invalidate                          Return lower text size limit         return             public float getMinTextSize             return mMinTextSize                        Set flag to add ellipsis to text that overflows at the smallest text size         param addEllipsis             public void setAddEllipsis boolean addEllipsis            mAddEllipsis   addEllipsis                        Return flag to add ellipsis to text that overflows at the smallest text size         return             public boolean getAddEllipsis             return mAddEllipsis                        Reset the text to the original size             public void resetTextSize             if  mTextSize  gt  0                super setTextSize TypedValue COMPLEX UNIT PX  mTextSize               mMaxTextSize   mTextSize                                  Resize text after measuring              Override     protected void onLayout boolean changed  int left  int top  int right  int bottom            if  changed    mNeedsResize                int widthLimit    right - left  - getCompoundPaddingLeft   - getCompoundPaddingRight                int heightLimit    bottom - top  - getCompoundPaddingBottom   - getCompoundPaddingTop                resizeText widthLimit  heightLimit                     super onLayout changed  left  top  right  bottom                         Resize the text size with default width and height             public void resizeText              int heightLimit   getHeight   - getPaddingBottom   - getPaddingTop            int widthLimit   getWidth   - getPaddingLeft   - getPaddingRight            resizeText widthLimit  heightLimit                         Resize the text size with specified width and height         param width         param height             public void resizeText int width  int height            CharSequence text   getText               Do not resize if the view does not have dimensions or there is no text         if  text    null    text length      0    height  lt   0    width  lt   0    mTextSize    0                return                     if  getTransformationMethod      null                text   getTransformationMethod   getTransformation text  this                         Get the text view s paint object         TextPaint textPaint   getPaint                Store the current text size         float oldTextSize   textPaint getTextSize               If there is a max text size set  use the lesser of that and the default text size         float targetTextSize   mMaxTextSize  gt  0   Math min mTextSize  mMaxTextSize    mTextSize              Get the required text height         int textHeight   getTextHeight text  textPaint  width  targetTextSize               Until we either fit within our text view or we had reached our min text size  incrementally try smaller sizes         while  textHeight  gt  height  amp  amp  targetTextSize  gt  mMinTextSize                targetTextSize   Math max targetTextSize - 2  mMinTextSize               textHeight   getTextHeight text  textPaint  width  targetTextSize                         If we had reached our minimum text size and still don t fit  append an ellipsis         if  mAddEllipsis  amp  amp  targetTextSize    mMinTextSize  amp  amp  textHeight  gt  height                   Draw using a static layout                modified  use a copy of TextPaint for measuring             TextPaint paint   new TextPaint textPaint                  Draw using a static layout             StaticLayout layout   new StaticLayout text  paint  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  false                  Check that we have a least one line of rendered text             if  layout getLineCount    gt  0                       Since the line at the specific vertical position would be cut off                     we must trim up to the previous line                 int lastLine   layout getLineForVertical height  - 1                     If the text would not even fit on a single line  clear it                 if  lastLine  lt  0                        setText                                           Otherwise  trim to the previous line and add an ellipsis                 else                       int start   layout getLineStart lastLine                       int end   layout getLineEnd lastLine                       float lineWidth   layout getLineWidth lastLine                       float ellipseWidth   textPaint measureText mEllipsis                           Trim characters off until we have enough room to draw the ellipsis                     while  width  lt  lineWidth   ellipseWidth                            lineWidth   textPaint measureText text subSequence start  --end   1  toString                                               setText text subSequence 0  end    mEllipsis                                                         Some devices try to auto adjust line spacing  so force default line spacing            and invalidate the layout as a side effect         setTextSize TypedValue COMPLEX UNIT PX  targetTextSize           setLineSpacing mSpacingAdd  mSpacingMult               Notify the listener if registered         if  mTextResizeListener    null                mTextResizeListener onTextResize this  oldTextSize  targetTextSize                         Reset force resize flag         mNeedsResize   false                Set the text size of the text paint object and use a static layout to render text off screen before measuring     private int getTextHeight CharSequence source  TextPaint paint  int width  float textSize               modified  make a copy of the original TextPaint object for measuring             apparently the object gets modified while measuring  see also the            docs for TextView getPaint    which states to access it read-only          TextPaint paintCopy   new TextPaint paint              Update the text paint object         paintCopy setTextSize textSize              Measure using a static layout         StaticLayout layout   new StaticLayout source  paintCopy  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true           return layout getHeight               Warning  There is an important fixed bug affecting Android 3 1 - 4 04 causing all AutoResizingTextView widgets not to work  Please read  https   stackoverflow com a 21851157 2075875

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Extend TextView and override onDraw with the code below  It will keep text aspect ratio but size it to fill the space  You could easily modify code to stretch if necessary      Override   protected void onDraw  NonNull Canvas canvas        TextPaint textPaint   getPaint        textPaint setColor getCurrentTextColor         textPaint setTextAlign Paint Align CENTER       textPaint drawableState   getDrawableState         String text   getText   toString        float desiredWidth   getMeasuredWidth   - getPaddingLeft   - getPaddingRight   - 2      float desiredHeight   getMeasuredHeight   - getPaddingTop   - getPaddingBottom   - 2      float textSize   textPaint getTextSize         for  int i   0  i  lt  10  i            textPaint getTextBounds text  0  text length    rect         float width   rect width          float height   rect height           float deltaWidth   width - desiredWidth        float deltaHeight   height - desiredHeight         boolean fitsWidth   deltaWidth  lt   0        boolean fitsHeight   deltaHeight  lt   0         if   fitsWidth  amp  amp  Math abs deltaHeight   lt  1 0                fitsHeight  amp  amp  Math abs deltaWidth   lt  1 0                close enough         break                 float adjustX   desiredWidth   width        float adjustY   desiredHeight   height         textSize   textSize    adjustY  lt  adjustX   adjustY   adjustX             adjust text size       textPaint setTextSize textSize             float x   desiredWidth   2f      float y   desiredHeight   2f - rect top - rect height     2f      canvas drawText text  x  y  textPaint

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Warning  bug in Android Honeycomb and Ice Cream Sandwich  Androids versions  3 1 - 4 04 have a bug  that setTextSize   inside of TextView works only for the 1st time  1st invocation    Bug is described here  http   code google com p android issues detail id 22493 http   code google com p android issues detail id 17343 c9  workaround is to add new line character to text assigned to TextView before changing size   final String DOUBLE BYTE SPACE     u3000   textView append DOUBLE BYTE SPACE     I use it in my code as follow   final String DOUBLE BYTE SPACE     u3000   AutoResizeTextView textView    AutoResizeTextView  view findViewById R id aTextView   String fixString       if  android os Build VERSION SDK INT  gt   android os Build VERSION CODES HONEYCOMB MR1     amp  amp  android os Build VERSION SDK INT  lt   android os Build VERSION CODES ICE CREAM SANDWICH MR1          fixString   DOUBLE BYTE SPACE    textView setText fixString    The text    fixString     I add this   u3000  character on left and right of my text  to keep it centered  If you have it aligned to left then append to the right only  Of course it can be also embedded with AutoResizeTextView widget  but I wanted to keep fix code outside

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I just borrow some other guys  idea and write some code below that may be helpful   import android content Context  import android graphics Canvas  import android text Layout Alignment  import android text StaticLayout  import android text TextPaint  import android text TextUtils  import android util AttributeSet  import android util TypedValue  import android widget TextView   public class AutoResizeTextView extends TextView       private static final int MAX SIZE   1000       private static final int MIN SIZE   5       private TextPaint mTextPaint       private float mSpacingMult   1 0f       private float mSpacingAdd   0 0f       private boolean needAdapt   false       private boolean adapting   false       public AutoResizeTextView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           init               public AutoResizeTextView Context context  AttributeSet attrs            super context  attrs           init               public AutoResizeTextView Context context            super context           init               private void init             mTextPaint   new TextPaint                Override     protected void onDraw Canvas canvas            if  adapting                return                    if  needAdapt                adaptTextSize              else               super onDraw canvas                        private void adaptTextSize             CharSequence text   getText            int viewWidth   getMeasuredWidth            int viewHeight   getMeasuredHeight             if  viewWidth  0    viewHeight  0                    TextUtils isEmpty text                 return                     adapting   true             binary search            int bottom MIN SIZE  top MAX SIZE  mid   0          while  bottom  lt   top                mid    bottom   top  2              mTextPaint setTextSize mid               int textWidth    int  mTextPaint measureText text  0  text length                 int textHeight   getTextHeight text  viewWidth               if  textWidth lt viewWidth  amp  amp  textHeight lt viewHeight                    bottom   mid 1                else                   top   mid-1                                   int newSize   mid-1          setTextSize TypedValue COMPLEX UNIT PX  newSize            adapting false          needAdapt   false           invalidate               private int getTextHeight CharSequence text  int targetWidth            StaticLayout layout   new StaticLayout text  mTextPaint  targetWidth                  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true           return layout getHeight                Override     protected void onSizeChanged int w  int h  int oldw  int oldh            super onSizeChanged w  h  oldw  oldh           needAdapt   true              Override     protected void onTextChanged CharSequence text  int start              int lengthBefore  int lengthAfter            super onTextChanged text  start  lengthBefore  lengthAfter           needAdapt   true              Override     public void setLineSpacing float add  float mult            super setLineSpacing add  mult           mSpacingMult   mult          mSpacingAdd   add

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I just created the following method  based on the ideas of Chase  which might help you if you want to draw text to any canvas   private static void drawText Canvas canvas  int xStart  int yStart          int xWidth  int yHeigth  String textToDisplay          TextPaint paintToUse  float startTextSizeInPixels          float stepSizeForTextSizeSteps            Text view line spacing multiplier     float mSpacingMult   1 0f         Text view additional line spacing     float mSpacingAdd   0 0f      StaticLayout l   null      do           paintToUse setTextSize startTextSizeInPixels           startTextSizeInPixels -  stepSizeForTextSizeSteps          l   new StaticLayout textToDisplay  paintToUse  xWidth                  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true         while  l getHeight    gt  yHeigth        int textCenterX   xStart    xWidth   2       int textCenterY    yHeigth - l getHeight      2       canvas save        canvas translate textCenterX  textCenterY       l draw canvas       canvas restore        This could be used e g  in any onDraw   method of any custom view

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Refer to the ScalableTextView java here Auto-fit TextView for Android  I have added the code to shrink and expand the TextView based on the text length

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I needed a specific solution  I have got an edittext and textview in my layout  The textview is fixed height and width  When the user starts to type in the edittext  the text should immediately appear in the textview  The text in the textfield should auto - resize to fit the textview  So I updated Chase s solution to work for me  So when the text changes in the textview  resizing starts  The difference between mine and Chase s soluton  resizing is done even if the user DELETE some chars  I hope it can help someone   public class TextFitTextView extends TextView       Minimum text size for this text view public static final float MIN TEXT SIZE   10      Maximum text size for this text view - if it is 0  then the text acts    like match parent public static final float MAX TEXT SIZE   0      Our ellipse string private static final String mEllipsis              Text size that is set from code  This acts as a starting point for    resizing private float mTextSize      Lower bounds for text size private float mMinTextSize   MIN TEXT SIZE      Max bounds for text size private float mMaxTextSize   MAX TEXT SIZE      Text view line spacing multiplier private float mSpacingMult   1 0f      Text view additional line spacing private float mSpacingAdd   0 0f      Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis   true      Add ellipsis to text that overflows at the smallest text size private int heightLimit  private int widthLimit      Default constructor override public TextFitTextView Context context        this context  null         Default constructor when inflating from XML file public TextFitTextView Context context  AttributeSet attrs        this context  attrs  0         Default constructor override public TextFitTextView Context context  AttributeSet attrs  int defStyle        super context  attrs  defStyle       mTextSize   getTextSize              When text changes resize the text size       Override protected void onTextChanged final CharSequence text  final int start  final int before  final int after           if we are adding new chars to text     if  before  lt   after  amp  amp  after    1            resizeText true              now we are deleting chars       else           resizeText false                   Override the set text size to update our internal reference values      Override public void setTextSize float size        super setTextSize size       mTextSize   getTextSize              Override the set text size to update our internal reference values      Override public void setTextSize int unit  float size        super setTextSize unit  size       mTextSize   getTextSize              Override the set line spacing to update our internal reference values      Override public void setLineSpacing float add  float mult        super setLineSpacing add  mult       mSpacingMult   mult      mSpacingAdd   add            Set the lower text size limit and invalidate the view         param minTextSize     public void setMinTextSize float minTextSize        mMinTextSize   minTextSize      requestLayout        invalidate              Return lower text size limit         return     public float getMinTextSize         return mMinTextSize            Set flag to add ellipsis to text that overflows at the smallest text size         param addEllipsis     public void setAddEllipsis boolean addEllipsis        mAddEllipsis   addEllipsis            Return flag to add ellipsis to text that overflows at the smallest text    size         return     public boolean getAddEllipsis         return mAddEllipsis            Get width and height limits      Override protected void onLayout boolean changed  int left  int top  int right  int bottom        if  widthLimit    0  amp  amp  heightLimit    0            widthLimit    right - left  - getCompoundPaddingLeft   - getCompoundPaddingRight            heightLimit    bottom - top  - getCompoundPaddingBottom   - getCompoundPaddingTop              super onLayout changed  left  top  right  bottom             Resize the text size with specified width and height         param width     param height     public void resizeText boolean increase        CharSequence text   getText           Do not resize if the view does not have dimensions or there is no        text     if  text    null    text length      0    heightLimit  lt   0    widthLimit  lt   0    mTextSize    0            return                Get the text view s paint object     TextPaint textPaint   getPaint            Get the required text height     int textHeight   getTextHeight text  textPaint  widthLimit  mTextSize            If the text length is increased         Until we either fit within our text view or we had reached our min        text size  incrementally try smaller sizes     if  increase            while  textHeight  gt  heightLimit  amp  amp  mTextSize  gt  mMinTextSize                mTextSize   Math max mTextSize - 2  mMinTextSize               textHeight   getTextHeight text  textPaint  widthLimit  mTextSize                            text length has been decreased     else               if max test size is set then add it to while condition         if  mMaxTextSize    0                while  textHeight  lt  heightLimit  amp  amp  mTextSize  lt   mMaxTextSize                    mTextSize   mTextSize   2                  textHeight   getTextHeight text  textPaint  widthLimit  mTextSize                           else               while  textHeight  lt  heightLimit                    mTextSize   mTextSize   2                  textHeight   getTextHeight text  textPaint  widthLimit  mTextSize                                   mTextSize   textHeight  gt  heightLimit   mTextSize - 2   mTextSize                If we had reached our minimum text size and still don t fit  append        an ellipsis     if  mAddEllipsis  amp  amp  mTextSize    mMinTextSize  amp  amp  textHeight  gt  heightLimit               Draw using a static layout         TextPaint paint   new TextPaint textPaint           StaticLayout layout   new StaticLayout text  paint  widthLimit  Alignment ALIGN NORMAL  mSpacingMult                  mSpacingAdd  false              Check that we have a least one line of rendered text         if  layout getLineCount    gt  0                   Since the line at the specific vertical position would be cut                off                 we must trim up to the previous line             int lastLine   layout getLineForVertical heightLimit  - 1                 If the text would not even fit on a single line  clear it             if  lastLine  lt  0                    setText                                   Otherwise  trim to the previous line and add an ellipsis             else                   int start   layout getLineStart lastLine                   int end   layout getLineEnd lastLine                   float lineWidth   layout getLineWidth lastLine                   float ellipseWidth   paint measureText mEllipsis                       Trim characters off until we have enough room to draw the                    ellipsis                 while  widthLimit  lt  lineWidth   ellipseWidth                        lineWidth   paint measureText text subSequence start  --end   1  toString                                       setText text subSequence 0  end    mEllipsis                                         Some devices try to auto adjust line spacing  so force default line        spacing        and invalidate the layout as a side effect     setTextSize TypedValue COMPLEX UNIT PX  mTextSize       setLineSpacing mSpacingAdd  mSpacingMult          Set the text size of the text paint object and use a static layout to    render text off screen before measuring private int getTextHeight CharSequence source  TextPaint originalPaint  int width  float textSize           Update the text paint object     TextPaint paint   new TextPaint originalPaint       paint setTextSize textSize          Measure using a static layout     StaticLayout layout   new StaticLayout source  paint  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd              true       return layout getHeight

User · Answer

From June 2018 Android officially started supporting this feature for Android 4 0  API level 14  and higher  Check it out at  Autosizing TextViews  With Android 8 0  API level 26  and higher     lt  xml version  1 0  encoding  utf-8   gt   lt TextView     android layout width  match parent      android layout height  200dp      android autoSizeTextType  uniform      android autoSizeMinTextSize  12sp      android autoSizeMaxTextSize  100sp      android autoSizeStepGranularity  2sp    gt    Programmatically    setAutoSizeTextTypeUniformWithConfiguration int autoSizeMinTextSize  int autoSizeMaxTextSize           int autoSizeStepGranularity  int unit   textView setAutoSizeTextTypeUniformWithConfiguration                  1  17  1  TypedValue COMPLEX UNIT DIP       Android versions prior to Android 8 0  API level 26      lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout     xmlns android  http   schemas android com apk res android      xmlns app  http   schemas android com apk res-auto      android layout width  match parent      android layout height  match parent  gt      lt TextView       android layout width  match parent        android layout height  200dp        app autoSizeTextType  uniform        app autoSizeMinTextSize  12sp        app autoSizeMaxTextSize  100sp        app autoSizeStepGranularity  2sp    gt    lt  LinearLayout gt    Programmatically    TextViewCompat setAutoSizeTextTypeUniformWithConfiguration  TextView textView  int autoSizeMinTextSize  int autoSizeMaxTextSize  int autoSizeStepGranularity  int unit    TextViewCompat setAutoSizeTextTypeUniformWithConfiguration textView  1  17  1  TypedValue COMPLEX UNIT DIP     Attention  TextView must have layout width  match parent  or absolute size

User · Answer

You can use the android text StaticLayout class for this  That s what TextView uses internally

User · Answer

Here s a simple solution that uses TextView itself with a TextChangedListened added to it     expressionView    TextView  findViewById R id expressionView   expressionView addTextChangedListener textAutoResizeWatcher expressionView  25  55     private TextWatcher textAutoResizeWatcher final TextView view  final int MIN SP  final int MAX SP        return new TextWatcher              Override         public void beforeTextChanged CharSequence charSequence  int i  int i1  int i2               Override         public void onTextChanged CharSequence charSequence  int i  int i1  int i2               Override         public void afterTextChanged Editable editable                 final int widthLimitPixels   view getWidth   - view getPaddingRight   - view getPaddingLeft                Paint paint   new Paint                float fontSizeSP   pixelsToSp view getTextSize                 paint setTextSize spToPixels fontSizeSP                 String viewText   view getText   toString                 float widthPixels   paint measureText viewText                   Increase font size if necessary              if  widthPixels  lt  widthLimitPixels                   while  widthPixels  lt  widthLimitPixels  amp  amp  fontSizeSP  lt   MAX SP                         fontSizeSP                      paint setTextSize spToPixels fontSizeSP                        widthPixels   paint measureText viewText                                     --fontSizeSP                               Decrease font size if necessary              else                   while  widthPixels  gt  widthLimitPixels    fontSizeSP  gt  MAX SP                        if  fontSizeSP  lt  MIN SP                            fontSizeSP   MIN SP                          break                                            --fontSizeSP                      paint setTextSize spToPixels fontSizeSP                        widthPixels   paint measureText viewText                                                view setTextSize fontSizeSP                       private float pixelsToSp float px        float scaledDensity   getResources   getDisplayMetrics   scaledDensity      return px scaledDensity     private float spToPixels float sp        float scaledDensity   getResources   getDisplayMetrics   scaledDensity      return sp   scaledDensity      This approach will increase or decrease the font size as needed to fit the text  respecting the MIN SP and MAX SP bounds received as parameters

User · Answer

Here is the approach I take  It s very simple  It uses successive approximation to zero in on the fontsize and can generally have it figured out in less than 10 iterations  Just replace  activityWidth  with the width of whatever view you are using to display the text in  In my example  it s set as a private field to the screen s width  The inital fontsize of 198 is only set in the event the method generates an exception  which really should never happen      private float GetFontSizeForScreenWidth String text          float fontsize   198       try             Paint paint   new Paint Paint ANTI ALIAS FLAG         paint setColor Color RED         Typeface typeface   Typeface create  Helvetica   Typeface BOLD         paint setTypeface typeface         paint setTextAlign Align CENTER          int lowVal   0        int highVal   2000        int currentVal   highVal                     Successively approximate the screen size until it is           within 2 pixels of the maximum screen width  Generally          this will get you to the closest font size within about 10          iterations                   do                 paint setTextSize currentVal           float textWidth   paint measureText text            float diff   activityWidth - textWidth           if   diff  gt   0   amp  amp   diff  lt   2                       fontsize   paint getTextSize              return fontsize                     if  textWidth  gt  activityWidth            highVal   currentVal          else if  textWidth  lt  activityWidth            lowVal   currentVal          else                     fontsize   paint getTextSize              return fontsize                     currentVal    highVal - lowVal    2   lowVal           while  true                   catch  Exception ex              return fontsize

User · Answer

I hope this helps you  import android content Context  import android graphics Rect  import android text TextPaint  import android util AttributeSet  import android widget TextView      Based on     from http   stackoverflow com questions 2617266 how-to-adjust-text-font-size-to-fit-textview     public class FontFitTextView extends TextView    private static float MAX TEXT SIZE   20   public FontFitTextView Context context        this context  null      public FontFitTextView Context context  AttributeSet attrs        super context  attrs        float size   this getTextSize        if  size  gt  MAX TEXT SIZE          setTextSize MAX TEXT SIZE      private void refitText String text  int textWidth        if  textWidth  gt  0            float availableWidth   textWidth - this getPaddingLeft                   - this getPaddingRight             TextPaint tp   getPaint            Rect rect   new Rect            tp getTextBounds text  0  text length    rect           float size   rect width             if  size  gt  availableWidth              setTextScaleX availableWidth   size             Override protected void onMeasure int widthMeasureSpec  int heightMeasureSpec        super onMeasure widthMeasureSpec  heightMeasureSpec       int parentWidth   MeasureSpec getSize widthMeasureSpec       int parentHeight   MeasureSpec getSize heightMeasureSpec       refitText this getText   toString    parentWidth       this setMeasuredDimension parentWidth  parentHeight       Override protected void onTextChanged final CharSequence text  final int start          final int before  final int after        refitText text toString    this getWidth         Override protected void onSizeChanged int w  int h  int oldw  int oldh        if  w    oldw            refitText this getText   toString    w               NOTE  I use MAX TEXT SIZE in case of text size is bigger than 20 because I don t want to allow big fonts applies to my View  if this is not your case  you can just simply remove it

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I wrote a blog post about this   I created a component called ResizableButton based on Kirill Grouchnikov s blog post about custom components used in the new android market app  I placed the src code here   On the other hand  mosabua read my post and told me he was going to open source his implementation which was faster than mine  I hope he release it soon enough

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I combined some of the above suggestions to make one that scales up and down  with bisection method  It also scales within the width                        DO WHAT YOU WANT TO PUBLIC LICENSE                       Version 2  December 2004       Copyright  C  2004 Sam Hocevar  lt sam hocevar net gt        Everyone is permitted to copy and distribute verbatim or modified    copies of this license document  and changing it is allowed as long    as the name is changed                   DO WHAT YOU WANT TO PUBLIC LICENSE      TERMS AND CONDITIONS FOR COPYING  DISTRIBUTION AND MODIFICATION        0  You just DO WHAT YOU WANT TO       import android content Context  import android text Layout Alignment  import android text StaticLayout  import android text TextPaint  import android util AttributeSet  import android util TypedValue  import android widget TextView          Text view that auto adjusts text size to fit within the view  If the text    size equals the minimum text size and still does not fit  append with an    ellipsis          author Chase Colburn     since Apr 4  2011     public class AutoResizeTextView extends TextView           Minimum text size for this text view     public static final float MIN TEXT SIZE   10          Minimum text size for this text view     public static final float MAX TEXT SIZE   128       private static final int BISECTION LOOP WATCH DOG   30          Interface for resize notifications     public interface OnTextResizeListener           public void onTextResize TextView textView  float oldSize  float newSize                 Our ellipse string     private static final String mEllipsis                  Registered resize listener     private OnTextResizeListener mTextResizeListener          Flag for text and or size changes to force a resize     private boolean mNeedsResize   false          Text size that is set from code  This acts as a starting point for        resizing     private float mTextSize          Temporary upper bounds on the starting text size     private float mMaxTextSize   MAX TEXT SIZE          Lower bounds for text size     private float mMinTextSize   MIN TEXT SIZE          Text view line spacing multiplier     private float mSpacingMult   1 0f          Text view additional line spacing     private float mSpacingAdd   0 0f          Add ellipsis to text that overflows at the smallest text size     private boolean mAddEllipsis   true          Default constructor override     public AutoResizeTextView Context context            this context  null                 Default constructor when inflating from XML file     public AutoResizeTextView Context context  AttributeSet attrs            this context  attrs  0                 Default constructor override     public AutoResizeTextView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           mTextSize   getTextSize                          When text changes  set the force resize flag to true and reset the text        size               Override     protected void onTextChanged final CharSequence text  final int start              final int before  final int after            mNeedsResize   true             Since this view may be reused  it is good to reset the text size         resetTextSize                          If the text view size changed  set the force resize flag to true              Override     protected void onSizeChanged int w  int h  int oldw  int oldh            if  w    oldw    h    oldh                mNeedsResize   true                                  Register listener to receive resize notifications                 param listener             public void setOnResizeListener OnTextResizeListener listener            mTextResizeListener   listener                        Override the set text size to update our internal reference values              Override     public void setTextSize float size            super setTextSize size           mTextSize   getTextSize                          Override the set text size to update our internal reference values              Override     public void setTextSize int unit  float size            super setTextSize unit  size           mTextSize   getTextSize                          Override the set line spacing to update our internal reference values              Override     public void setLineSpacing float add  float mult            super setLineSpacing add  mult           mSpacingMult   mult          mSpacingAdd   add                        Set the upper text size limit and invalidate the view                 param maxTextSize             public void setMaxTextSize float maxTextSize            mMaxTextSize   maxTextSize          requestLayout            invalidate                          Return upper text size limit                 return             public float getMaxTextSize             return mMaxTextSize                        Set the lower text size limit and invalidate the view                 param minTextSize             public void setMinTextSize float minTextSize            mMinTextSize   minTextSize          requestLayout            invalidate                          Return lower text size limit                 return             public float getMinTextSize             return mMinTextSize                        Set flag to add ellipsis to text that overflows at the smallest text size                 param addEllipsis             public void setAddEllipsis boolean addEllipsis            mAddEllipsis   addEllipsis                        Return flag to add ellipsis to text that overflows at the smallest text        size                 return             public boolean getAddEllipsis             return mAddEllipsis                        Reset the text to the original size             public void resetTextSize             if  mTextSize  gt  0                super setTextSize TypedValue COMPLEX UNIT PX  mTextSize                  mMaxTextSize   mTextSize                                  Resize text after measuring               Override     protected void onLayout boolean changed  int left  int top  int right              int bottom            if  changed    mNeedsResize                int widthLimit    right - left  - getCompoundPaddingLeft                       - getCompoundPaddingRight                int heightLimit    bottom - top  - getCompoundPaddingBottom                       - getCompoundPaddingTop                resizeText widthLimit  heightLimit                     super onLayout changed  left  top  right  bottom                         Resize the text size with default width and height             public void resizeText                 Height and width with a padding as a percentage of height         int heightLimit   getHeight   - getPaddingBottom   - getPaddingTop            int widthLimit   getWidth   - getPaddingLeft   - getPaddingRight            resizeText widthLimit  heightLimit                         Resize the text size with specified width and height                 param width         param height             public void resizeText int width  int height            CharSequence text   getText                Do not resize if the view does not have dimensions or there is no            text         if  text    null    text length      0    height  lt   0    width  lt   0                    mTextSize    0                return                        Get the text view s paint object         TextPaint textPaint   getPaint                Store the current text size         float oldTextSize   textPaint getTextSize                Bisection method  fast  amp  precise         float lower   mMinTextSize          float upper   mMaxTextSize          int loop counter   1          float targetTextSize    lower   upper    2          int textHeight   getTextHeight text  textPaint  width  targetTextSize           int textWidth   getTextWidth text  textPaint  width  targetTextSize            while  loop counter  lt  BISECTION LOOP WATCH DOG  amp  amp  upper - lower  gt  1                targetTextSize    lower   upper    2              textHeight   getTextHeight text  textPaint  width  targetTextSize               textWidth   getTextWidth text  textPaint  width  targetTextSize               if  textHeight  gt   height     textWidth  gt   width                   upper   targetTextSize              else                 lower   targetTextSize              loop counter                       targetTextSize   lower          textHeight   getTextHeight text  textPaint  width  targetTextSize               If we had reached our minimum text size and still don t fit  append            an ellipsis         if  mAddEllipsis  amp  amp  targetTextSize    mMinTextSize                  amp  amp  textHeight  gt  height                   Draw using a static layout                modified  use a copy of TextPaint for measuring             TextPaint paintCopy   new TextPaint textPaint               paintCopy setTextSize targetTextSize               StaticLayout layout   new StaticLayout text  paintCopy  width                      Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  false                  Check that we have a least one line of rendered text             if  layout getLineCount    gt  0                       Since the line at the specific vertical position would be cut                    off                     we must trim up to the previous line                 int lastLine   layout getLineForVertical height  - 1                     If the text would not even fit on a single line  clear it                 if  lastLine  lt  0                        setText                                           Otherwise  trim to the previous line and add an ellipsis                 else                       int start   layout getLineStart lastLine                       int end   layout getLineEnd lastLine                       float lineWidth   layout getLineWidth lastLine                       float ellipseWidth   paintCopy measureText mEllipsis                           Trim characters off until we have enough room to draw the                        ellipsis                     while  width  lt  lineWidth   ellipseWidth                            lineWidth   paintCopy measureText text subSequence                                  start  --end   1  toString                                               setText text subSequence 0  end    mEllipsis                                                         Some devices try to auto adjust line spacing  so force default line            spacing            and invalidate the layout as a side effect         setTextSize TypedValue COMPLEX UNIT PX  targetTextSize           setLineSpacing mSpacingAdd  mSpacingMult               Notify the listener if registered         if  mTextResizeListener    null                mTextResizeListener onTextResize this  oldTextSize  targetTextSize                         Reset force resize flag         mNeedsResize   false                Set the text size of the text paint object and use a static layout to        render text off screen before measuring     private int getTextHeight CharSequence source  TextPaint originalPaint              int width  float textSize               modified  make a copy of the original TextPaint object for measuring             apparently the object gets modified while measuring  see also the            docs for TextView getPaint    which states to access it read-only          TextPaint paint   new TextPaint originalPaint              Update the text paint object         paint setTextSize textSize              Measure using a static layout         StaticLayout layout   new StaticLayout source  paint  width                  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true           return layout getHeight                  Set the text size of the text paint object and use a static layout to        render text off screen before measuring     private int getTextWidth CharSequence source  TextPaint originalPaint              int width  float textSize               Update the text paint object         TextPaint paint   new TextPaint originalPaint              Draw using a static layout         paint setTextSize textSize            StaticLayout layout   new StaticLayout source  paint  width                  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true            return  int  layout getLineWidth 0

User · Answer

UPDATE  Following code  also fulfills the requirement of an ideal  AutoScaleTextView as described here   Auto-fit TextView for Android and is marked as winner   UPDATE 2  Support of maxlines added  now works fine before API level 16   Update 3  Support for android drawableLeft  android drawableRight  android drawableTop and android drawableBottom tags added  thanks to MartinH s simple fix here     My requirements were little bit different  I needed an efficient way to adjust size because I was animating an integer from  may be 0 to  4000 in TextView in 2 seconds and I wanted to adjust the size accordingly  My solution works bit differently  Here is what final result looks like      and the code that produced it    lt LinearLayout xmlns android  http   schemas android com apk res android      android layout width  wrap content      android layout height  wrap content      android orientation  vertical      android padding  16dp   gt        lt com vj widgets AutoResizeTextView         android layout width  match parent          android layout height  100dp          android ellipsize  none          android maxLines  2          android text  Auto Resized Text  max 2 lines          android textSize  100sp    gt   lt  -- maximum size -- gt        lt com vj widgets AutoResizeTextView         android layout width  match parent          android layout height  100dp          android ellipsize  none          android gravity  center          android maxLines  1          android text  Auto Resized Text  max 1 line          android textSize  100sp    gt   lt  -- maximum size -- gt        lt com vj widgets AutoResizeTextView         android layout width  match parent          android layout height  wrap content          android text  Auto Resized Text          android textSize  500sp    gt   lt  -- maximum size -- gt    lt  LinearLayout gt    And finally the java code   import android annotation TargetApi  import android content Context  import android content res Resources  import android graphics RectF  import android os Build  import android text Layout Alignment  import android text StaticLayout  import android text TextPaint  import android util AttributeSet  import android util SparseIntArray  import android util TypedValue  import android widget TextView   public class AutoResizeTextView extends TextView   private interface SizeTester                           param suggestedSize                   Size of text to be tested         param availableSpace                   available space in which text must fit         return an integer  lt  0 if after applying   code suggestedSize  to                text  it takes less space than   code availableSpace    gt  0                otherwise             public int onTestSize int suggestedSize  RectF availableSpace      private RectF mTextRect   new RectF     private RectF mAvailableSpaceRect   private SparseIntArray mTextCachedSizes   private TextPaint mPaint   private float mMaxTextSize   private float mSpacingMult   1 0f   private float mSpacingAdd   0 0f   private float mMinTextSize   20   private int mWidthLimit   private static final int NO LINE LIMIT   -1  private int mMaxLines   private boolean mEnableSizeCache   true  private boolean mInitiallized   public AutoResizeTextView Context context        super context       initialize       public AutoResizeTextView Context context  AttributeSet attrs        super context  attrs       initialize       public AutoResizeTextView Context context  AttributeSet attrs  int defStyle        super context  attrs  defStyle       initialize       private void initialize         mPaint   new TextPaint getPaint         mMaxTextSize   getTextSize        mAvailableSpaceRect   new RectF        mTextCachedSizes   new SparseIntArray        if  mMaxLines    0               no value was assigned during construction         mMaxLines   NO LINE LIMIT            mInitiallized   true      Override public void setText final CharSequence text  BufferType type        super setText text  type       adjustTextSize text toString         Override public void setTextSize float size        mMaxTextSize   size      mTextCachedSizes clear        adjustTextSize getText   toString         Override public void setMaxLines int maxlines        super setMaxLines maxlines       mMaxLines   maxlines      reAdjust       public int getMaxLines         return mMaxLines      Override public void setSingleLine         super setSingleLine        mMaxLines   1      reAdjust        Override public void setSingleLine boolean singleLine        super setSingleLine singleLine       if  singleLine            mMaxLines   1        else           mMaxLines   NO LINE LIMIT            reAdjust        Override public void setLines int lines        super setLines lines       mMaxLines   lines      reAdjust        Override public void setTextSize int unit  float size        Context c   getContext        Resources r       if  c    null          r   Resources getSystem        else         r   c getResources        mMaxTextSize   TypedValue applyDimension unit  size              r getDisplayMetrics         mTextCachedSizes clear        adjustTextSize getText   toString         Override public void setLineSpacing float add  float mult        super setLineSpacing add  mult       mSpacingMult   mult      mSpacingAdd   add            Set the lower text size limit and invalidate the view         param minTextSize     public void setMinTextSize float minTextSize        mMinTextSize   minTextSize      reAdjust       private void reAdjust         adjustTextSize getText   toString        private void adjustTextSize String string        if   mInitiallized            return            int startSize    int  mMinTextSize      int heightLimit   getMeasuredHeight   - getCompoundPaddingBottom           - getCompoundPaddingTop        mWidthLimit   getMeasuredWidth   - getCompoundPaddingLeft           - getCompoundPaddingRight        mAvailableSpaceRect right   mWidthLimit      mAvailableSpaceRect bottom   heightLimit      super setTextSize              TypedValue COMPLEX UNIT PX              efficientTextSizeSearch startSize   int  mMaxTextSize                      mSizeTester  mAvailableSpaceRect       private final SizeTester mSizeTester   new SizeTester          TargetApi Build VERSION CODES JELLY BEAN       Override     public int onTestSize int suggestedSize  RectF availableSPace            mPaint setTextSize suggestedSize           String text   getText   toString            boolean singleline   getMaxLines      1          if  singleline                mTextRect bottom   mPaint getFontSpacing                mTextRect right   mPaint measureText text             else               StaticLayout layout   new StaticLayout text  mPaint                      mWidthLimit  Alignment ALIGN NORMAL  mSpacingMult                      mSpacingAdd  true                  return early if we have more lines             if  getMaxLines      NO LINE LIMIT                      amp  amp  layout getLineCount    gt  getMaxLines                      return 1                            mTextRect bottom   layout getHeight                int maxWidth   -1              for  int i   0  i  lt  layout getLineCount    i                      if  maxWidth  lt  layout getLineWidth i                         maxWidth    int  layout getLineWidth i                                               mTextRect right   maxWidth                     mTextRect offsetTo 0  0           if  availableSPace contains mTextRect                    may be too small  don t worry we will find the best match             return -1            else                  too big             return 1                             Enables or disables size caching  enabling it will improve performance    where you are animating a value inside TextView  This stores the font    size against getText   length   Be careful though while enabling it as 0    takes more space than 1 on some fonts and so on          param enable               enable font size caching     public void enableSizeCache boolean enable        mEnableSizeCache   enable      mTextCachedSizes clear        adjustTextSize getText   toString        private int efficientTextSizeSearch int start  int end          SizeTester sizeTester  RectF availableSpace        if   mEnableSizeCache            return binarySearch start  end  sizeTester  availableSpace             String text   getText   toString        int key   text    null   0   text length        int size   mTextCachedSizes get key       if  size    0            return size            size   binarySearch start  end  sizeTester  availableSpace       mTextCachedSizes put key  size       return size     private static int binarySearch int start  int end  SizeTester sizeTester          RectF availableSpace        int lastBest   start      int lo   start      int hi   end - 1      int mid   0      while  lo  lt   hi            mid    lo   hi   gt  gt  gt  1          int midValCmp   sizeTester onTestSize mid  availableSpace           if  midValCmp  lt  0                lastBest   lo              lo   mid   1            else if  midValCmp  gt  0                hi   mid - 1              lastBest   hi            else               return mid                         make sure to return last best        this is what should always be returned     return lastBest       Override protected void onTextChanged final CharSequence text  final int start          final int before  final int after        super onTextChanged text  start  before  after       reAdjust        Override protected void onSizeChanged int width  int height  int oldwidth          int oldheight        mTextCachedSizes clear        super onSizeChanged width  height  oldwidth  oldheight       if  width    oldwidth    height    oldheight            reAdjust

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Here s yet another solution  just for kicks   It s probably not very efficient  but it does cope with both height and width of the text  and with marked-up text    Override protected void onMeasure final int widthMeasureSpec  final int heightMeasureSpec        if   MeasureSpec getMode widthMeasureSpec     MeasureSpec UNSPECIFIED               amp  amp   MeasureSpec getMode heightMeasureSpec     MeasureSpec UNSPECIFIED              final float desiredWidth   MeasureSpec getSize widthMeasureSpec           final float desiredHeight   MeasureSpec getSize heightMeasureSpec            float textSize   getTextSize            float lastScale   Float NEGATIVE INFINITY          while  textSize  gt  MINIMUM AUTO TEXT SIZE PX                   Measure how big the textview would like to be with the current text size              super onMeasure MeasureSpec UNSPECIFIED  MeasureSpec UNSPECIFIED                   Calculate how much we d need to scale it to fit the desired size  and                apply that scaling to the text size as an estimate of what we need              final float widthScale   desiredWidth   getMeasuredWidth                final float heightScale   desiredHeight   getMeasuredHeight                final float scale   Math min widthScale  heightScale                   If we don t need to shrink the text  or we don t seem to be converging  we re done              if   scale  gt   1f      scale  lt   lastScale                     break                                Shrink the text size and keep trying              textSize   Math max  float  Math floor scale   textSize   MINIMUM AUTO TEXT SIZE PX               setTextSize TypedValue COMPLEX UNIT PX  textSize               lastScale   scale                      super onMeasure widthMeasureSpec  heightMeasureSpec

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At google IO conference in 2017  google introduced autoSize property of TextView  https   youtu be fjUdJ2aVqE4   lt android support v7 widget AppCompatTextView         android layout width  match parent          android layout height  match parent          android text   string my text          app autoSizeTextType  uniform          app autoSizeMaxTextSize  10sp          app autoSizeMinTextSize  6sp          app autoSizeStepGranularity  1sp   gt

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Since I ve been looking for this forever  and I found a solution a while ago which is missing here  I m gonna write it here  for future reference also   Note  this code was taken directly from Google Android Lollipop dialer a while back  I don t remember If changes were made at the time  Also  I don t know which license is this under  but I have reason to think it is Apache 2 0   Class ResizeTextView  the actual View   public class ResizeTextView extends TextView    private final int mOriginalTextSize  private final int mMinTextSize  private final static int sMinSize   20  public ResizeTextView Context context  AttributeSet attrs        super context  attrs       mOriginalTextSize    int  getTextSize        mMinTextSize    int  sMinSize     Override protected void onTextChanged CharSequence text  int start  int lengthBefore  int lengthAfter        super onTextChanged text  start  lengthBefore  lengthAfter       ViewUtil resizeText this  mOriginalTextSize  mMinTextSize      Override protected void onSizeChanged int w  int h  int oldw  int oldh        super onSizeChanged w  h  oldw  oldh       ViewUtil resizeText this  mOriginalTextSize  mMinTextSize       This ResizeTextView class could extend TextView and all its children as I undestand  so EditText as well   Class ViewUtil with method resizeText            Copyright  C  2012 The Android Open Source Project     Licensed under the Apache License  Version 2 0  the  License      you may not use this file except in compliance with the License    You may obtain a copy of the License at          http   www apache org licenses LICENSE-2 0     Unless required by applicable law or agreed to in writing  software   distributed under the License is distributed on an  AS IS  BASIS    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND  either express or implied    See the License for the specific language governing permissions and   limitations under the License      import android graphics Paint  import android util TypedValue  import android widget TextView   public class ViewUtil        private ViewUtil           public static void resizeText TextView textView  int originalTextSize  int minTextSize            final Paint paint   textView getPaint            final int width   textView getWidth            if  width    0  return          textView setTextSize TypedValue COMPLEX UNIT PX  originalTextSize           float ratio   width   paint measureText textView getText   toString             if  ratio  lt   1 0f                textView setTextSize TypedValue COMPLEX UNIT PX                      Math max minTextSize  originalTextSize   ratio                        You should set your view as   lt yourpackage yourapp ResizeTextView             android layout width  match parent              android layout height  64dp              android gravity  center              android maxLines  1   gt    Hope it helps

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Thanks to Chase and onoelle  for the lazy programmers  let me post here a working version of their fantastic merged code  adapted on a Button  instead of a TextView   Substitute all your Buttons  not ImageButtons  with AutoResizeTextButtons and the same boring problem is fixed for them too   Here is the code  I just removed the imports                     DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE                       Version 2  December 2004        Copyright  C  2004 Sam Hocevar  lt sam hocevar net gt         Everyone is permitted to copy and distribute verbatim or modified    copies of this license document  and changing it is allowed as long    as the name is changed                    DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE      TERMS AND CONDITIONS FOR COPYING  DISTRIBUTION AND MODIFICATION         0  You just DO WHAT THE FUCK YOU WANT TO      made better by onoelle     adapted for button by beppi             Text Button that auto adjusts text size to fit within the view     If the text size equals the minimum text size and still does not    fit  append with an ellipsis          author Chase Colburn     since Apr 4  2011     public class AutoResizeTextButton extends Button           Minimum text size for this text view     public static final float MIN TEXT SIZE   20          Interface for resize notifications     public interface OnTextResizeListener           public void onTextResize Button textView  float oldSize  float newSize                 Our ellipse string     private static final String mEllipsis                  Registered resize listener     private OnTextResizeListener mTextResizeListener          Flag for text and or size changes to force a resize     private boolean mNeedsResize   false          Text size that is set from code  This acts as a starting point for resizing     private float mTextSize          Temporary upper bounds on the starting text size     private float mMaxTextSize   0          Lower bounds for text size     private float mMinTextSize   MIN TEXT SIZE          Text view line spacing multiplier     private float mSpacingMult   1 0f          Text view additional line spacing     private float mSpacingAdd   0 0f          Add ellipsis to text that overflows at the smallest text size     private boolean mAddEllipsis   true          Default constructor override     public AutoResizeTextButton Context context            this context  null                 Default constructor when inflating from XML file     public AutoResizeTextButton Context context  AttributeSet attrs            this context  attrs  0                 Default constructor override     public AutoResizeTextButton Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           mTextSize   getTextSize                          When text changes  set the force resize flag to true and reset the text size               Override     protected void onTextChanged final CharSequence text  final int start  final int before  final int after            mNeedsResize   true             Since this view may be reused  it is good to reset the text size         resetTextSize                          If the text view size changed  set the force resize flag to true              Override     protected void onSizeChanged int w  int h  int oldw  int oldh            if  w    oldw    h    oldh                mNeedsResize   true                                  Register listener to receive resize notifications         param listener             public void setOnResizeListener OnTextResizeListener listener            mTextResizeListener   listener                        Override the set text size to update our internal reference values              Override     public void setTextSize float size            super setTextSize size           mTextSize   getTextSize                          Override the set text size to update our internal reference values              Override     public void setTextSize int unit  float size            super setTextSize unit  size           mTextSize   getTextSize                          Override the set line spacing to update our internal reference values              Override     public void setLineSpacing float add  float mult            super setLineSpacing add  mult           mSpacingMult   mult          mSpacingAdd   add                        Set the upper text size limit and invalidate the view         param maxTextSize             public void setMaxTextSize float maxTextSize            mMaxTextSize   maxTextSize          requestLayout            invalidate                          Return upper text size limit         return             public float getMaxTextSize             return mMaxTextSize                        Set the lower text size limit and invalidate the view         param minTextSize             public void setMinTextSize float minTextSize            mMinTextSize   minTextSize          requestLayout            invalidate                          Return lower text size limit         return             public float getMinTextSize             return mMinTextSize                        Set flag to add ellipsis to text that overflows at the smallest text size         param addEllipsis             public void setAddEllipsis boolean addEllipsis            mAddEllipsis   addEllipsis                        Return flag to add ellipsis to text that overflows at the smallest text size         return             public boolean getAddEllipsis             return mAddEllipsis                        Reset the text to the original size             public void resetTextSize             if mTextSize  gt  0                super setTextSize TypedValue COMPLEX UNIT PX  mTextSize               mMaxTextSize   mTextSize                                  Resize text after measuring              Override     protected void onLayout boolean changed  int left  int top  int right  int bottom            if changed    mNeedsResize                int widthLimit    right - left  - getCompoundPaddingLeft   - getCompoundPaddingRight                int heightLimit    bottom - top  - getCompoundPaddingBottom   - getCompoundPaddingTop                resizeText widthLimit  heightLimit                     super onLayout changed  left  top  right  bottom                          Resize the text size with default width and height             public void resizeText             int heightLimit   getHeight   - getPaddingBottom   - getPaddingTop            int widthLimit   getWidth   - getPaddingLeft   - getPaddingRight            resizeText widthLimit  heightLimit                         Resize the text size with specified width and height         param width         param height             public void resizeText int width  int height            CharSequence text   getText               Do not resize if the view does not have dimensions or there is no text         if text    null    text length      0    height  lt   0    width  lt   0    mTextSize    0                return                        Get the text view s paint object         TextPaint textPaint   getPaint                Store the current text size         float oldTextSize   textPaint getTextSize               If there is a max text size set  use the lesser of that and the default text size         float targetTextSize   mMaxTextSize  gt  0   Math min mTextSize  mMaxTextSize    mTextSize              Get the required text height         int textHeight   getTextHeight text  textPaint  width  targetTextSize               Until we either fit within our text view or we had reached our min text size  incrementally try smaller sizes         while textHeight  gt  height  amp  amp  targetTextSize  gt  mMinTextSize                targetTextSize   Math max targetTextSize - 2  mMinTextSize               textHeight   getTextHeight text  textPaint  width  targetTextSize                         If we had reached our minimum text size and still don t fit  append an ellipsis         if mAddEllipsis  amp  amp  targetTextSize    mMinTextSize  amp  amp  textHeight  gt  height                   Draw using a static layout                modified  use a copy of TextPaint for measuring             TextPaint paint   new TextPaint textPaint               StaticLayout layout   new StaticLayout text  paint  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  false                  Check that we have a least one line of rendered text             if layout getLineCount    gt  0                       Since the line at the specific vertical position would be cut off                     we must trim up to the previous line                 int lastLine   layout getLineForVertical height  - 1                     If the text would not even fit on a single line  clear it                 if lastLine  lt  0                        setText                                           Otherwise  trim to the previous line and add an ellipsis                 else                       int start   layout getLineStart lastLine                       int end   layout getLineEnd lastLine                       float lineWidth   layout getLineWidth lastLine                       float ellipseWidth   textPaint measureText mEllipsis                           Trim characters off until we have enough room to draw the ellipsis                     while width  lt  lineWidth   ellipseWidth                            lineWidth   textPaint measureText text subSequence start  --end   1  toString                                               setText text subSequence 0  end    mEllipsis                                                         Some devices try to auto adjust line spacing  so force default line spacing            and invalidate the layout as a side effect         textPaint setTextSize targetTextSize           modified  setting text size via this setTextSize  instead of textPaint setTextSize targetTextSize           setTextSize TypedValue COMPLEX UNIT PX  targetTextSize           setLineSpacing mSpacingAdd  mSpacingMult               Notify the listener if registered         if mTextResizeListener    null                mTextResizeListener onTextResize this  oldTextSize  targetTextSize                         Reset force resize flag         mNeedsResize   false                Set the text size of the text paint object and use a static layout to render text off screen before measuring     private int getTextHeight CharSequence source  TextPaint originalPaint  int width  float textSize                 modified  make a copy of the original TextPaint object for measuring               apparently the object gets modified while measuring  see also the              docs for TextView getPaint    which states to access it read-only             Update the text paint object           TextPaint paint   new TextPaint originalPaint           paint setTextSize textSize              Measure using a static layout         StaticLayout layout   new StaticLayout source  paint  width  Alignment ALIGN NORMAL  mSpacingMult  mSpacingAdd  true           return layout getHeight               Usage   put a AutoResizeTextButton inside your xml in replace of a normal Button  without changing anything else  Inside the onCreate   put  for example        myButton    AutoResizeTextButton getView   findViewById id myButton       myButton setMinTextSize 8f       myButton resizeText

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Providing this version of top answer rewritten on C  for those who codes on Xamarin Android  Worked for me well                         DO WHAT YOU WANT TO PUBLIC LICENSE                       Version 2  December 2004        Copyright  C  2004 Sam Hocevar  lt sam hocevar net gt         Everyone is permitted to copy and distribute verbatim or modified    copies of this license document  and changing it is allowed as long    as the name is changed                    DO WHAT YOU WANT TO PUBLIC LICENSE      TERMS AND CONDITIONS FOR COPYING  DISTRIBUTION AND MODIFICATION         0  You just DO WHAT YOU WANT TO        using System  using Android Content  using Android Runtime  using Android Text  using Android Util  using Android Widget  using Java Lang   namespace App GuestGuide Droid Controls       public class OnTextResizeEventArgs   EventArgs               public TextView TextView   get  set            public float OldSize   get  set            public float NewSize   get  set                    lt inheritdoc   gt           lt summary gt          Text view that auto adjusts text size to fit within the view          If the text size equals the minimum text size and still does not         fit  append with an ellipsis           lt  summary gt      public class AutoResizeTextView   TextView                    lt summary gt              Minimum text size for this text view              lt  summary gt          public static float MIN TEXT SIZE   10                lt summary gt              Our ellipse string              lt  summary gt          private const string Ellipsis                    private float  mMaxTextSize           private float  mMinTextSize   MIN TEXT SIZE                lt summary gt              Register subscriber to receive resize notifications              lt  summary gt          public event EventHandler lt OnTextResizeEventArgs gt  OnTextResize                lt summary gt              Flag for text and or size changes to force a resize              lt  summary gt          private bool  needsResize                lt summary gt              Text size that is set from code  This acts as a starting point for resizing              lt  summary gt          private float  textSize                lt summary gt              Text view line spacing multiplier              lt  summary gt          private float  spacingMult   1 0f                lt summary gt              Text view additional line spacing              lt  summary gt          private float  spacingAdd                lt summary gt              Add ellipsis to text that overflows at the smallest text size              lt  summary gt          public bool ShouldAddEllipsis   get  set                  lt inheritdoc   gt               lt summary gt              Override the set text size to update our internal reference values              lt  summary gt          public override float TextSize                       get   gt  base TextSize              set                               base TextSize   value                   textSize   TextSize                                        lt summary gt              Temporary upper bounds on the starting text size              lt  summary gt          public float MaxTextSize                       get   gt   mMaxTextSize                 Set the upper text size limit and invalidate the view             set                                mMaxTextSize   value                  RequestLayout                    Invalidate                                          lt summary gt              Lower bounds for text size              lt  summary gt          public float MinTextSize                       get   gt   mMinTextSize                Set the lower text size limit and invalidate the view             set                                mMinTextSize   value                  RequestLayout                    Invalidate                                     public AutoResizeTextView Context context    this context  null                               public AutoResizeTextView Context context  IAttributeSet attrs    this context  attrs  0                               public AutoResizeTextView Context context  IAttributeSet attrs  int defStyleAttr    base context  attrs  defStyleAttr                         textSize   TextSize                     public AutoResizeTextView Context context  IAttributeSet attrs  int defStyleAttr  int defStyleRes    base context  attrs  defStyleAttr  defStyleRes                         textSize   TextSize                     protected AutoResizeTextView IntPtr javaReference  JniHandleOwnership transfer    base javaReference  transfer                         textSize   TextSize                          lt inheritdoc   gt               lt summary gt              When text changes  set the force resize flag to true and reset the text size               lt  summary gt               lt param name  text  gt  lt  param gt               lt param name  start  gt  lt  param gt               lt param name  lengthBefore  gt  lt  param gt               lt param name  lengthAfter  gt  lt  param gt          protected override void OnTextChanged ICharSequence text  int start  int lengthBefore  int lengthAfter                         needsResize   true                 Since this view may be reused  it is good to reset the text size             ResetTextSize                            lt inheritdoc   gt               lt summary gt              If the text view size changed  set the force resize flag to true              lt  summary gt               lt param name  w  gt  lt  param gt               lt param name  h  gt  lt  param gt               lt param name  oldw  gt  lt  param gt               lt param name  oldh  gt  lt  param gt          protected override void OnSizeChanged int w  int h  int oldw  int oldh                        if  w    oldw    h    oldh                                 needsResize   true                                   public override void SetTextSize  GeneratedEnum  ComplexUnitType unit  float size                        base SetTextSize unit  size                textSize   TextSize                          lt inheritdoc   gt               lt summary gt              Override the set line spacing to update our internal reference values              lt  summary gt               lt param name  add  gt  lt  param gt               lt param name  mult  gt  lt  param gt          public override void SetLineSpacing float add  float mult                        base SetLineSpacing add  mult                spacingMult   mult               spacingAdd   add                          lt summary gt              Reset the text to the original size              lt  summary gt          public void ResetTextSize                         if   textSize  gt  0                                base SetTextSize ComplexUnitType Px   textSize                    mMaxTextSize    textSize                                        lt inheritdoc   gt               lt summary gt              Resize text after measuring              lt  summary gt               lt param name  changed  gt  lt  param gt               lt param name  left  gt  lt  param gt               lt param name  top  gt  lt  param gt               lt param name  right  gt  lt  param gt               lt param name  bottom  gt  lt  param gt          protected override void OnLayout bool changed  int left  int top  int right  int bottom                        if  changed     needsResize                                var widthLimit    right - left  - CompoundPaddingLeft - CompoundPaddingRight                  var heightLimit    bottom - top  - CompoundPaddingBottom - CompoundPaddingTop                  ResizeText widthLimit  heightLimit                              base OnLayout changed  left  top  right  bottom                           lt summary gt              Resize the text size with default width and height              lt  summary gt          public void ResizeText                         var heightLimit   Height - PaddingBottom - PaddingTop              var widthLimit   Width - PaddingLeft - PaddingRight              ResizeText widthLimit  heightLimit                           lt summary gt              Resize the text size with specified width and height              lt  summary gt               lt param name  width  gt  lt  param gt               lt param name  height  gt  lt  param gt          public void ResizeText int width  int height                        ICharSequence text   null               if   string IsNullOrEmpty Text                                 text   new Java Lang String Text                                 Do not resize if the view does not have dimensions or there is no text             if  text    null    text Length      0    height  lt   0    width  lt   0     textSize    0                                return                             if  TransformationMethod    null                                text   TransformationMethod GetTransformationFormatted text  this                                 Get the text view s paint object             var textPaint   Paint                 Store the current text size             var oldTextSize   textPaint TextSize                 If there is a max text size set  use the lesser of that and the default text size             var targetTextSize    mMaxTextSize  gt  0   System Math Min  textSize   mMaxTextSize     textSize                  Get the required text height             var textHeight   GetTextHeight text  textPaint  width  targetTextSize                   Until we either fit within our text view or we had reached our min text size  incrementally try smaller sizes             while  textHeight  gt  height  amp  amp  targetTextSize  gt   mMinTextSize                                targetTextSize   System Math Max targetTextSize - 2   mMinTextSize                   textHeight   GetTextHeight text  textPaint  width  targetTextSize                                 If we had reached our minimum text size and still don t fit  append an ellipsis             if  ShouldAddEllipsis  amp  amp  targetTextSize     mMinTextSize  amp  amp  textHeight  gt  height                                   Draw using a static layout                    modified  use a copy of TextPaint for measuring                 var paint   new TextPaint textPaint                      Draw using a static layout                 var layout   new StaticLayout text  paint  width  Layout Alignment AlignNormal   spacingMult   spacingAdd  false                       Check that we have a least one line of rendered text                 if  layout LineCount  gt  0                                           Since the line at the specific vertical position would be cut off                         we must trim up to the previous line                     var lastLine   layout GetLineForVertical height  - 1                         If the text would not even fit on a single line  clear it                     if  lastLine  lt  0                                                Text   string Empty                                               Otherwise  trim to the previous line and add an ellipsis                     else                                               var start   layout GetLineStart lastLine                           var end   layout GetLineEnd lastLine                           var lineWidth   layout GetLineWidth lastLine                           var ellipseWidth   textPaint MeasureText Ellipsis                               Trim characters off until we have enough room to draw the ellipsis                         while  width  lt  lineWidth   ellipseWidth                                                        lineWidth   textPaint MeasureText text SubSequence start  --end   1                                                       Text   text SubSequence 0  end    Ellipsis                                                                        Some devices try to auto adjust line spacing  so force default line spacing                and invalidate the layout as a side effect             SetTextSize ComplexUnitType Px  targetTextSize               SetLineSpacing  spacingAdd   spacingMult                var notifyArgs   new OnTextResizeEventArgs                               TextView   this                  NewSize   targetTextSize                  OldSize   oldTextSize                                Notify the listener if registered             OnTextResize  Invoke this  notifyArgs                   Reset force resize flag              needsResize   false                          lt summary gt              Set the text size of the text paint object and use a static layout to render text off screen before measuring              lt  summary gt               lt param name  source  gt  lt  param gt               lt param name  paint  gt  lt  param gt               lt param name  width  gt  lt  param gt               lt param name  textSize  gt  lt  param gt               lt returns gt  lt  returns gt          private int GetTextHeight ICharSequence source  TextPaint paint  int width  float textSize                           modified  make a copy of the original TextPaint object for measuring                 apparently the object gets modified while measuring  see also the                docs for TextView getPaint    which states to access it read-only                 Update the text paint object             var paintCopy   new TextPaint paint                                TextSize   textSize                                Measure using a static layout             var layout   new StaticLayout source  paintCopy  width  Layout Alignment AlignNormal   spacingMult   spacingAdd  true                return layout Height

User · Answer

Here s an enumeration of what else I ve found for anyone still searching    1  Here s a solution that recursively re-paints the textview until it fits  This means literally watching your text shrink into place  but at least it fits when it s done  The code will need some tweaking to implement  but it s mostly there    2  You can try hacking together a custom solution like this  or dunni s class in this  which is what I did using the getPaint   measureText str  to search for the right size  but it got a lot messier since I need it to wrap only on whitespace     3  You can keep searching- I ve tried more alternatives than I can count  Ted s advice on StaticLayout hasn t paid off for me but maybe there s something there  I tried using the StaticLayout getEllipsis line  to determine if text was going off screen  to no effect  See my  presently un-answered  post about that here

User · Answer

Actually a solution is in Google s DialogTitle class    though it s not as effective as the accepted one  it s a lot simpler and is easy to adapt   public class SingleLineTextView extends TextView      public SingleLineTextView Context context  AttributeSet attrs  int defStyle        super context  attrs  defStyle       setSingleLine        setEllipsize TruncateAt END          public SingleLineTextView Context context  AttributeSet attrs        super context  attrs       setSingleLine        setEllipsize TruncateAt END          public SingleLineTextView Context context        super context       setSingleLine        setEllipsize TruncateAt END           Override   protected void onMeasure int widthMeasureSpec  int heightMeasureSpec        super onMeasure widthMeasureSpec  heightMeasureSpec        final Layout layout   getLayout        if  layout    null          final int lineCount   layout getLineCount          if  lineCount  gt  0            final int ellipsisCount   layout getEllipsisCount lineCount - 1           if  ellipsisCount  gt  0               final float textSize   getTextSize                  textSize is already expressed in pixels           setTextSize TypedValue COMPLEX UNIT PX   textSize - 1               super onMeasure widthMeasureSpec  heightMeasureSpec

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My method is       public void changeTextSize int initialSize  TextView tv         DisplayMetrics displayMetrics   new DisplayMetrics        getWindowManager   getDefaultDisplay   getMetrics displayMetrics       double width   displayMetrics widthPixels   displayMetrics xdpi      double height   displayMetrics heightPixels   displayMetrics ydpi       Log i  LOG    The width of the tested emulator is      width       Log i  LOG    The height of the tested emulator is      height        double scale   Math min width   2 25  height   4 0     See the logcat  gt  gt  gt  width   2 25 and heigt   4 0     tv setTextSize TypedValue COMPLEX UNIT SP   int   initialSize   scale         For example   changeTextSize 16  findViewById R id myTextView    changeTextSize 12  findViewById R id myEditText

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I found the following to work nicely for me   It doesn t loop and accounts for both height and width   Note that it is important to specify the PX unit when calling setTextSize on the view     Paint paint   adjustTextSize getPaint    numChars  maxWidth  maxHeight   setTextSize TypedValue COMPLEX UNIT PX paint getTextSize       Here is the routine I use  passing in the getPaint   from the view   A 10 character string with a  wide  character is used to estimate the width independent from the actual string   private static final String text10  OOOOOOOOOO   public static Paint adjustTextSize Paint paint  int numCharacters  int widthPixels  int heightPixels        float width   paint measureText text10  numCharacters text10 length        float newSize    int   widthPixels width  paint getTextSize         paint setTextSize newSize           remeasure with font size near our desired result     width   paint measureText text10  numCharacters text10 length        newSize    int   widthPixels width  paint getTextSize         paint setTextSize newSize           Check height constraints     FontMetricsInt metrics   paint getFontMetricsInt        float textHeight   metrics descent-metrics ascent      if  textHeight  gt  heightPixels            newSize    int  newSize    heightPixels textHeight            paint setTextSize newSize              return paint

[android] Auto Scale TextView Text to Fit within Bounds

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