Android: Need to use onSizeChanged for View.getWidth/Height() in class extending Activity

Question

I want to use getWidth()/getHeight() to get width/height of my XML-Layout. I read I have to do it in the method onSizeChanged() otherwise I will get 0 ( Android: Get the scr

Answer 1

You dont have to create a customView to get its height and width. You can add an OnLayoutChangedListener (description here) to the view whose width/height you want, and then essentially get the values in the onLayoutChanged method, like so

View myView = findViewById(R.id.my_view);
myView.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) {
            // its possible that the layout is not complete in which case
            // we will get all zero values for the positions, so ignore the event
            if (left == 0 && top == 0 && right == 0 && bottom == 0) {
                return;
            }

           // Do what you need to do with the height/width since they are now set
        }
    });

The reason for this is because views are drawn only after the layout is complete. The system then walks down the view heirarchy tree to measure the width/height of each view before drawing them.