View s getWidth and getHeight returns 0

Question

I am creating all of the elements in my android project dynamically  I am trying to get the width and height of a button so that I can rotate that button around  I am just trying to learn how to work with the android language  However  it returns 0    I did some research and I saw that it needs to be done somewhere other than in the onCreate   method  If someone can give me an example of how to do it  that would be great    Here is my current code   package com animation   import android app Activity  import android os Bundle  import android view animation Animation  import android view animation LinearInterpolator  import android view animation RotateAnimation  import android widget Button  import android widget LinearLayout   public class AnimateScreen extends Activity       Called when the activity is first created   Override public void onCreate Bundle savedInstanceState        super onCreate savedInstanceState        LinearLayout ll   new LinearLayout this        LinearLayout LayoutParams layoutParams   new LinearLayout LayoutParams LinearLayout LayoutParams WRAP CONTENT  LinearLayout LayoutParams WRAP CONTENT       layoutParams setMargins 30  20  30  0        Button bt   new Button this       bt setText String valueOf bt getWidth           RotateAnimation ra   new RotateAnimation 0 360 bt getWidth     2 bt getHeight     2       ra setDuration 3000L       ra setRepeatMode Animation RESTART       ra setRepeatCount Animation INFINITE       ra setInterpolator new LinearInterpolator          bt startAnimation ra        ll addView bt layoutParams        setContentView ll       Any help is appreciated

User · Answer

AndroidX has multiple extension functions that help you with this kind of work, inside androidx.core.view

You need to use Kotlin for this.

The one that best fits here is doOnLayout:

Performs the given action when this view is laid out. If the view has been laid out and it has not requested a layout, the action will be performed straight away otherwise, the action will be performed after the view is next laid out.

The action will only be invoked once on the next layout and then removed.

In your example:

bt.doOnLayout {
    val ra = RotateAnimation(0,360,it.width / 2,it.height / 2)
    // more code
}

Dependency: androidx.core:core-ktx:1.0.0

User · Answer

I would rather use OnPreDrawListener   instead of addOnGlobalLayoutListener    since it is called a bit earlier than other listeners      view getViewTreeObserver   addOnPreDrawListener new ViewTreeObserver OnPreDrawListener                  Override         public boolean onPreDraw                         if  view getViewTreeObserver   isAlive                    view getViewTreeObserver   removeOnPreDrawListener this                               put your code here             return true

User · Answer

You are calling getWidth   too early  The UI has not been sized and laid out on the screen yet   I doubt you want to be doing what you are doing  anyway -- widgets being animated do not change their clickable areas  and so the button will still respond to clicks in the original orientation regardless of how it has rotated   That being said  you can use a dimension resource to define the button size  then reference that dimension resource from your layout file and your source code  to avoid this problem

User · Answer

Height and width are zero because view has not been created by the time you are requesting it s height and width    One simplest solution is   view post new Runnable              Override         public void run                 view getHeight      height is ready             view getWidth      width is ready                     This method is good as compared to other methods as it is short and crisp

User · Answer

We can use    Override  public void onWindowFocusChanged boolean hasFocus      super onWindowFocusChanged hasFocus       Here you can get the size

User · Answer

Maybe this helps someone   Create an extension function for the View class     filename  ViewExt kt   fun View afterLayout what     - gt  Unit        if isLaidOut            what invoke         else           viewTreeObserver addOnGlobalLayoutListener object   ViewTreeObserver OnGlobalLayoutListener               override fun onGlobalLayout                     viewTreeObserver removeOnGlobalLayoutListener this                  what invoke                                      This can then be used on any view with   view afterLayout       do something with view height

User · Answer

If you need to get width of some widget before it is displayed on screen  you can use getMeasuredWidth   or getMeasuredHeight     myImage measure LayoutParams WRAP CONTENT  LayoutParams WRAP CONTENT   int width   myImage getMeasuredWidth    int height   myImage getMeasuredHeight

User · Answer

We need to wait for view will be drawn  For this purpose use OnPreDrawListener  Kotlin example    val preDrawListener   object   ViewTreeObserver OnPreDrawListener                    override fun onPreDraw    Boolean                       view viewTreeObserver removeOnPreDrawListener this                          code which requires view size parameters                      return true                                              view viewTreeObserver addOnPreDrawListener preDrawListener

User · Answer

It happens because the view needs more time to be inflated  So instead of calling view width and view height on the main thread  you should use view post         to make sure that your view has already been inflated  In Kotlin   view post width  view post height    In Java you can also call getWidth   and getHeight   methods in a Runnable and pass the Runnable to view post   method   view post new Runnable              Override         public void run                 view getWidth                 view getHeight

User · Answer

A Kotlin Extension to observe on the global layout and perform a given task when height is ready dynamically   Usage   view height   Log i  Info    Here is your height     it      Implementation   fun  lt T   View gt  T height function   Int  - gt  Unit        if  height    0          viewTreeObserver addOnGlobalLayoutListener object   ViewTreeObserver OnGlobalLayoutListener               override fun onGlobalLayout                     viewTreeObserver removeOnGlobalLayoutListener this                  function height                               else function height

User · Answer

The basic problem is  that you have to wait for the drawing phase for the actual measurements  especially with dynamic values like wrap content or match parent   but usually this phase hasn t been finished up to onResume    So you need a workaround for waiting for this phase  There a are different possible solutions to this  1  Listen to Draw Layout Events  ViewTreeObserver A ViewTreeObserver gets fired for different drawing events  Usually the OnGlobalLayoutListener is what you want for getting the measurement  so the code in the listener will be called after the layout phase  so the measurements are ready  view getViewTreeObserver   addOnGlobalLayoutListener new ViewTreeObserver OnGlobalLayoutListener                  Override             public void onGlobalLayout                     view getViewTreeObserver   removeOnGlobalLayoutListener this                   view getHeight      height is ready                            Note  The listener will be immediately removed because otherwise it will fire on every layout event  If you have to support apps SDK Lvl  lt  16 use this to unregister the listener  public void removeGlobalOnLayoutListener  ViewTreeObserver OnGlobalLayoutListener victim   2  Add a runnable to the layout queue  View post   Not very well known and my favourite solution  Basically just use the View s post method with your own runnable  This basically queues your code after the view s measure  layout  etc  as stated by Romain Guy   The UI event queue will process events in order  After setContentView   is invoked  the event queue will contain a message asking for a relayout  so anything you post to the queue will happen after the layout pass  Example  final View view   smth      view post new Runnable                  Override             public void run                     view getHeight      height is ready                            The advantage over ViewTreeObserver   your code is only executed once and you don t have to disable the Observer after execution which can be a hassle less verbose syntax  References   https   stackoverflow com a 3602144 774398 https   stackoverflow com a 3948036 774398     3  Overwrite Views s onLayout Method This is only practical in certain situation when the logic can be encapsulated in the view itself  otherwise this is a quite verbose and cumbersome syntax  view   new View this         Override     protected void onLayout boolean changed  int l  int t  int r  int b            super onLayout changed  l  t  r  b           view getHeight      height is ready           Also mind  that onLayout will be called many times  so be considerate what you do in the method  or disable your code after the first time  4  Check if has been through layout phase If you have code that is executing multiple times while creating the ui you could use the following support v4 lib method  View viewYouNeedHeightFrom           if ViewCompat isLaidOut viewYouNeedHeightFrom        viewYouNeedHeightFrom getHeight        Returns true if view has been through at least one layout since it was last attached to or detached from a window   Additional  Getting staticly defined measurements If it suffices to just get the statically defined height width  you can just do this with   View getMeasuredWidth   View getMeasuredHeigth    But mind you  that this might be different to the actual width height after drawing  The javadoc describes the difference in more detail   The size of a view is expressed with a width and a height  A view actually possess two pairs of width and height values  The first pair is known as measured width and measured height  These dimensions define how big a view wants to be within its parent  see Layout for more details   The measured dimensions can be obtained by calling getMeasuredWidth   and getMeasuredHeight    The second pair is simply known as width and height  or sometimes drawing width and drawing height  These dimensions define the actual size of the view on screen  at drawing time and after layout  These values may  but do not have to  be different from the measured width and height  The width and height can be obtained by calling getWidth   and getHeight

User · Answer

This is a little old  but was having trouble with this myself  needing to animate objects in a fragment when it is created    This solution worked for me  I believe it is self explanatory  class YourFragment  Fragment         var width   0     var height   0   override fun onCreateView      inflater  LayoutInflater  container  ViewGroup       savedInstanceState  Bundle     View           Inflate the layout for this fragment     val root   inflater inflate R layout fragment winner splash  container  false      container  width let           if  it    null                width   it                     container  height let           if  it    null                height   it                          return root

User · Answer

Gone views returns 0 as height if app in background  This my code  1oo  works   fun View postWithTreeObserver postJob   View  Int  Int  - gt  Unit        viewTreeObserver addOnGlobalLayoutListener object   ViewTreeObserver OnGlobalLayoutListener           override fun onGlobalLayout                 val widthSpec   View MeasureSpec makeMeasureSpec 0  View MeasureSpec UNSPECIFIED              val heightSpec   View MeasureSpec makeMeasureSpec 0  View MeasureSpec UNSPECIFIED              measure widthSpec  heightSpec              postJob this postWithTreeObserver  measuredWidth  measuredHeight              if  Build VERSION SDK INT  lt  Build VERSION CODES JELLY BEAN                     Suppress  DEPRECATION                   viewTreeObserver removeGlobalOnLayoutListener this                else                   viewTreeObserver removeOnGlobalLayoutListener this

User · Answer

Answer with post is incorrect  because the size might not be recalculated  Another important thing is that the view and all it ancestors must be visible  For that I use a property View isShown   Here is my kotlin function  that can be placed somewhere in utils   fun View onInitialized onInit     - gt  Unit        viewTreeObserver addOnGlobalLayoutListener object   OnGlobalLayoutListener           override fun onGlobalLayout                 if  isShown                    viewTreeObserver removeOnGlobalLayoutListener this                  onInit                                      And the usage is   myView onInitialized       Log d TAG   width is      myView width

User · Answer

As Ian states in this Android Developers thread      Anyhow  the deal is that layout of the   contents of a window happens   after all the elements are constructed and added to their parent   views   It has to be this way  because   until you know what components a View   contains  and what they contain  and   so on  there s no sensible way you can   lay it out       Bottom line  if you call getWidth     etc  in a constructor  it will return   zero   The procedure is to create all   your view elements in the constructor    then wait for your View s   onSizeChanged   method to be called --   that s when you first find out your   real size  so that s when you set up   the sizes of your GUI elements       Be aware too that onSizeChanged   is   sometimes called with parameters of   zero -- check for this case  and   return immediately  so you don t get a   divide by zero when calculating your   layout  etc     Some time later it   will be called with the real values

User · Answer

One liner if you are using RxJava  amp  RxBindings  Similar approach without the boilerplate  This also solves the hack to suppress warnings as in the answer by Tim Autin   RxView layoutChanges yourView  take 1         subscribe aVoid - gt                  width and height have been calculated here             This is it  No need to be unsubscribe  even if never called

User · Answer

I used this solution  which I think is better than onWindowFocusChanged    If you open a DialogFragment  then rotate the phone  onWindowFocusChanged will be called only when the user closes the dialog        yourView getViewTreeObserver   addOnGlobalLayoutListener new ViewTreeObserver OnGlobalLayoutListener               Override         public void onGlobalLayout                    Ensure you call it only once               yourView getViewTreeObserver   removeGlobalOnLayoutListener this                   Here you can get the size                        Edit   as removeGlobalOnLayoutListener is deprecated  you should now do     SuppressLint  NewApi    SuppressWarnings  deprecation    Override public void onGlobalLayout             Ensure you call it only once       if android os Build VERSION SDK INT  gt   android os Build VERSION CODES JELLY BEAN            yourView getViewTreeObserver   removeOnGlobalLayoutListener this             else           yourView getViewTreeObserver   removeGlobalOnLayoutListener this                 Here you can get the size

User · Answer

If you are using Kotlin    leftPanel viewTreeObserver addOnGlobalLayoutListener object   ViewTreeObserver OnGlobalLayoutListener                override fun onGlobalLayout                      if android os Build VERSION SDK INT  gt   android os Build VERSION CODES JELLY BEAN                        leftPanel viewTreeObserver removeOnGlobalLayoutListener this                                    else                       leftPanel viewTreeObserver removeGlobalOnLayoutListener this                                        Here you can get the size                    leftThreshold   leftPanel width

[java] View's getWidth() and getHeight() returns 0

Examples related to java

Examples related to android

Examples related to android-layout

Examples related to getter