Android getWidth=0

You cannot use the width/height/getMeasuredWidth/getMeasuredHeight on a View before the system renders it (typically from onCreate/onResume).

solution1

Simple solution for this is to post a Runnable to the layout. The runnable will be executed after the View has been laid out.
because :
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

BoxesLayout = (RelativeLayout) findViewById(R.id.BoxesLinearLayout);
BoxesLayout.post(new Runnable() {
    @Override
    public void run() {
        int w = BoxesLayout.getMeasuredWidth();
        int h = BoxesLayout.getMeasuredHeight();

        ...
    }
});

solution2

Use the ViewTreeObserver on the View to wait for the first layout. Only after the first layout will getWidth()/getHeight()/getMeasuredWidth()/getMeasuredHeight() work.

ViewTreeObserver viewTreeObserver = view.getViewTreeObserver();
if (viewTreeObserver.isAlive()) {
  viewTreeObserver.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
      view.getViewTreeObserver().removeGlobalOnLayoutListener(this);
      viewWidth = mediaGallery.getWidth();
      viewHeight = mediaGallery.getHeight();
    }
  });
}

solution3

获取getMeasuredWidth之前先measure一下

myImage.measure(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);  
int height = myImage.getMeasuredHeight();  
int width = myImage.getMeasuredWidth();