How to detect a layout resize?

Question

Dianne Hackborn mentioned in a couple threads that you can detect when a layout as been resized, for example, when the soft keyboard opens or closes. Such a thread is this one... http://groups.google.com/group/android-developers/browse_thread/thread/d318901586313204/2b2c2c7d4bb04e1b

However, I didn't understand her answer: "By your view hierarchy being resized with all of the corresponding layout traversal and callbacks."

Does anyone have a further description or some examples of how to detect this? Which callbacks can I link into in order to detect this?

Thanks

Michael Allan · Answer 1 · 2020-01-07T19:19:51.333

One way is View.addOnLayoutChangeListener. There's no need to subclass the view in this case. But you do need API level 11. And the correct calculation of size from bounds (undocumented in the API) can sometimes be a pitfall. Here's a correct example:

view.addOnLayoutChangeListener( new View.OnLayoutChangeListener()
{
    public void onLayoutChange( View v,
      int left,    int top,    int right,    int bottom,
      int leftWas, int topWas, int rightWas, int bottomWas )
    {
        int widthWas = rightWas - leftWas; // Right exclusive, left inclusive
        if( v.getWidth() != widthWas )
        {
            // Width has changed
        }
        int heightWas = bottomWas - topWas; // Bottom exclusive, top inclusive
        if( v.getHeight() != heightWas )
        {
            // Height has changed
        }
    }
});

Another way (as dacwe answers) is to subclass your view and override onSizeChanged.

Warning. This may be called too many times with equals parameters — Style-7, Jan 25 '22 at 13:16

score 69 · Accepted Answer · answered Nov 13 '10 at 20:56

69

Override onSizeChanged in your View!

answered Nov 13 '10 at 20:56

dacwe

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I was hoping for a method that didn't require subclassing the view, but this does work exactly as I wanted, thank you. To get the call up to the view's parent activity I created a listener in the subclassed view that calls up to the activity that it has been resized. Thanks again. – cottonBallPaws Nov 13 '10 at 23:29
@dacwe how to stop resize layout ' – PriyankaChauhan Nov 15 '16 at 14:28

score 4 · Answer 3 · answered Nov 03 '15 at 22:23

My solution is to add an invisible tiny dumb view at the end of of the layout / fragment (or add it as a background), thus any change on size of the layout will trigger the layout change event for that view which could be catched up by OnLayoutChangeListener:

Example of adding the dumb view to the end of the layout:

 <View 
    android:id="@+id/theDumbViewId"
    android:layout_width="1dp"
    android:layout_height="1dp"
     />

Listen the event:

    View dumbView = mainView.findViewById(R.id.theDumbViewId);
    dumbView.addOnLayoutChangeListener(new OnLayoutChangeListener() {
        @Override
        public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
            // Your code about size changed
        }
    });

score 4 · Answer 4 · answered Apr 09 '21 at 09:48

With Kotlin extensions:

inline fun View?.onSizeChange(crossinline runnable: () -> Unit) = this?.apply {
    addOnLayoutChangeListener { _, left, top, right, bottom, oldLeft, oldTop, oldRight, oldBottom ->
        val rect = Rect(left, top, right, bottom)
        val oldRect = Rect(oldLeft, oldTop, oldRight, oldBottom)
        if (rect.width() != oldRect.width() || rect.height() != oldRect.height()) {
            runnable();
        }
    }
}

Use thus:

myView.onSizeChange { 
     // Do you thing...
}

score 1 · Answer 5 · edited May 05 '20 at 21:52

Thank to https://stackoverflow.com/users/2402790/michael-allan this is the good and simple way if you don't want to override all your views. As Api has evolved I would suggest this copy paste instead:

    String TAG="toto";
    ///and last listen for size changed
    YourView.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
        @Override
        public void onLayoutChange(View v,
                                   int left, int top, int right, int bottom,
                                   int oldLeft, int oldTop, int oldRight, int oldBottom) {

           boolean widthChanged = (right-left) != (oldRight-oldLeft);
            if( widthChanged )
            {
                // width has changed
                Log.e(TAG,"Width has changed new width is "+(right-left)+"px");
            }
            boolean heightChanged = (bottom-top) != (oldBottom-oldTop);
            if( heightChanged)
            {
                // height has changed
                Log.e(TAG,"height has changed new height is "+(bottom-top)+"px");
            }
        }
    });

score 1 · Answer 6 · answered Nov 11 '21 at 05:49

View.doOnLayout(crossinline action: (view: View) -> Unit): Unit

See docs.

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.

score 0 · Answer 7 · answered Jan 27 '22 at 08:50

Kotlin version base on @Michael Allan answer to detect layout size change

binding.root.addOnLayoutChangeListener { view, left, top, right, bottom, oldLeft, oldTop, oldRight, oldBottom ->
    if(view.height != oldBottom - oldTop) {
        // height changed
    }
    if(view.width != oldRight - oldLeft) {
        // width changed
    }
}

How to detect a layout resize?

7 Answers7

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