Obtain the View component width and ViewTreeObserver,

Obtain the View component width and ViewTreeObserver,
View width and height measurement method:

There are three measurement methods:

1)(Directly in onCreate)

int w = View.MeasureSpec.makeMeasureSpec(0,View.MeasureSpec.UNSPECIFIED);  int h = View.MeasureSpec.makeMeasureSpec(0,View.MeasureSpec.UNSPECIFIED);  imageView.measure(w, h);  int height =imageView.getMeasuredHeight();  int width =imageView.getMeasuredWidth();  textView.append("\n"+height+","+width);

2)Both 2 and 3 get the width and height of the component after onCreate () is called.

ViewTreeObserver vto = imageView.getViewTreeObserver();  vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {      public boolean onPreDraw() {          int height = imageView.getMeasuredHeight();          int width = imageView.getMeasuredWidth();          textView.append("\n"+height+","+width);          return true;      }  });

3)

ViewTreeObserver vto2 = imageView.getViewTreeObserver();    vto2.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {      @Override        public void onGlobalLayout() {          imageView.getViewTreeObserver().removeGlobalOnLayoutListener(this);            textView.append("\n\n"+imageView.getHeight()+","+imageView.getWidth());      }    });

Note: method 1 performs onMeasure calculation once more than other methods, and the callback function of method 2 is called multiple times.