Measuring text height to be drawn on Canvas Android

Question

Any straight forward way to measure the height of text  The way I am doing it now is by using Paint s measureText   to get the width  then by trial and error finding a value to get an approximate height  I ve also been messing around with FontMetrics  but all these seem like approximate methods that suck   I am trying to scale things for different resolutions  I can do it  but I end up with incredibly verbose code with lots of calculations to determine relative sizes  I hate it  There has to be a better way

User · Accepted Answer

What about paint getTextBounds    object method

User · Answer

You must use Rect width   and Rect Height   which returned from getTextBounds   instead  That works for me

User · Answer

The height is the text size you have set on the Paint variable   Another way to find out the height is   mPaint getTextSize

User · Answer

You can simply get the text size for a Paint object using getTextSize   method  For example   Paint mTextPaint   new Paint  Paint ANTI ALIAS FLAG     use densityMultiplier to take into account different pixel densities final float densityMultiplier   getContext   getResources                getDisplayMetrics   density    mTextPaint setTextSize 24 0f densityMultiplier           float size   mTextPaint getTextSize

User · Answer

bramp s answer is correct - partially  in that it does not mention that the calculated boundaries will be the minimum rectangle that contains the text fully with implicit start coordinates of 0  0     This means  that the height of  for example  Py  will be different from the height of  py  or  hi  or  oi  or  aw  because pixel-wise they require different heights    This by no means is an equivalent to FontMetrics in classic java   While width of a text is not much of a pain  height is   In particular  if you need to vertically center-align the drawn text  try getting the boundaries of the text  a   without quotes   instead of using the text you intend to draw  Works for me     Here s what I mean   Paint paint   new Paint Paint ANTI ALIAS FLAG   Paint LINEAR TEXT FLAG    paint setStyle Paint Style FILL   paint setColor color   paint setTextAlign Paint Align CENTER   paint setTextSize textSize    Rect bounds   new Rect    paint getTextBounds  a   0  1  bounds    buffer drawText this myText  canvasWidth  gt  gt  1   canvasHeight   bounds height     gt  gt  1  paint      remember x  gt  gt  1 is equivalent to x   2  but works much much faster   Vertically center aligning the text means vertically center align the bounding rectangle - which is different for different texts  caps  long letters etc   But what we actually want to do is to also align the baselines of rendered texts  such that they did not appear elevated or grooved  So  as long as we know the center of the smallest letter   a  for example  we then can reuse its alignment for the rest of the texts  This will center align all the texts as well as baseline-align them

User · Answer

There are different ways to measure the height depending on what you need  getTextBounds If you are doing something like precisely centering a small amount of fixed text  you probably want getTextBounds  You can get the bounding rectangle like this Rect bounds   new Rect    mTextPaint getTextBounds mText  0  mText length    bounds   int height   bounds height     As you can see for the following images  different strings will give different heights  shown in red    These differing heights could be a disadvantage in some situations when you just need a constant height no matter what the text is  See the next section  Paint FontMetrics You can calculate the hight of the font from the font metrics  The height is always the same because it is obtained from the font  not any particular text string  Paint FontMetrics fm   mTextPaint getFontMetrics    float height   fm descent - fm ascent   The baseline is the line that the text sits on  The descent is generally the furthest a character will go below the line and the ascent is generally the furthest a character will go above the line  To get the height you have to subtract ascent because it is a negative value   The baseline is y 0 and y descreases up the screen   Look at the following image  The heights for both of the strings are 234 375   If you want the line height rather than just the text height  you could do the following  float height   fm bottom - fm top   fm leading     265 4297  These are the bottom and top of the line  The leading  interline spacing  is usually zero  but you should add it anyway  The images above come from this project  You can play around with it to see how Font Metrics work  StaticLayout For measuring the height of multi-line text you should use a StaticLayout  I talked about it in some detail in this answer  but the basic way to get this height is like this  String text    quot This is some text  This is some text  This is some text  This is some text  This is some text  This is some text  quot    TextPaint myTextPaint   new TextPaint    myTextPaint setAntiAlias true   myTextPaint setTextSize 16   getResources   getDisplayMetrics   density   myTextPaint setColor 0xFF000000    int width   200  Layout Alignment alignment   Layout Alignment ALIGN NORMAL  float spacingMultiplier   1  float spacingAddition   0  boolean includePadding   false   StaticLayout myStaticLayout   new StaticLayout text  myTextPaint  width  alignment  spacingMultiplier  spacingAddition  includePadding    float height   myStaticLayout getHeight

User · Answer

You could use the android text StaticLayout class to specify the bounds required and then call getHeight    You can draw the text  contained in the layout  by calling its draw Canvas  method

User · Answer

If anyone still has problem  this is my code    I have a custom view which is square  width   height  and I want to assign a character to it  onDraw   shows how to get height of character  although I m not using it  Character will be displayed in the middle of view   public class SideBarPointer extends View        private static final String TAG    SideBarPointer        private Context context      private String label           private int width      private int height       public SideBarPointer Context context            super context           this context   context          init               public SideBarPointer Context context  AttributeSet attrs            super context  attrs           this context   context          init               public SideBarPointer Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           this context   context          init               private void init               setBackgroundColor 0x64FF0000               Override     public void onMeasure int widthMeasureSpec  int heightMeasureSpec           super onMeasure widthMeasureSpec  heightMeasureSpec            height   this getMeasuredHeight            width   this getMeasuredWidth             setMeasuredDimension width  width              protected void onDraw Canvas canvas            float mDensity   context getResources   getDisplayMetrics   density          float mScaledDensity   context getResources   getDisplayMetrics   scaledDensity           Paint previewPaint   new Paint            previewPaint setColor 0x0C2727           previewPaint setAlpha 200           previewPaint setAntiAlias true            Paint previewTextPaint   new Paint            previewTextPaint setColor Color WHITE           previewTextPaint setAntiAlias true           previewTextPaint setTextSize 90   mScaledDensity           previewTextPaint setShadowLayer 5  1  2  Color argb 255  87  87  87             float previewTextWidth   previewTextPaint measureText label             float previewTextHeight   previewTextPaint descent   - previewTextPaint ascent            RectF previewRect   new RectF 0  0  width  width            canvas drawRoundRect previewRect  5   mDensity  5   mDensity  previewPaint           canvas drawText label   width - previewTextWidth  2  previewRect top - previewTextPaint ascent    previewTextPaint            super onDraw canvas              public void setLabel String label            this label   label          Log e TAG   Label      label            this invalidate

[android] Measuring text height to be drawn on Canvas ( Android )

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