When in the Activity life cycle are UI elements available to be measured?

Question

I am defining some animations based on the inflated dimensions of some UI controls. What is the earliest point in the Activity life cycle I can tap into to know when the UI elements have been sized and I can query them for their dimensions?

Here lies the answer you seek. http://stackoverflow.com/questions/4142090/how-do-you-to-retrieve-dimensions-of-a-view-getheight-and-getwidth-always-r — DeeV, Mar 09 '12 at 19:51
@Deev put that as an answer and I'll mark it accepted. That was the solution I was looking for and it worked — Rich, Mar 10 '12 at 01:34

Jean-Philippe Roy · Answer 1 · 2012-03-09T19:51:37.283

2

Right after you set the Content of you Activity via the setContentView() method is the earliest I've been able to grab information from my widgets (size, text and others).

edited Mar 09 '12 at 19:51

answered Mar 09 '12 at 19:42

Jean-Philippe Roy

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score 1 · Accepted Answer · edited May 23 '17 at 12:05

Per Rich's request:

You can determine when the width and height by using the GlobalLayoutListener like so:

final View myView = findViewById(R.id.id_of_view);
ViewTreeObserver vto = myView.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
  @Override
  public void onGlobalLayout() {
    int viewHeight = myView.getHeight();
    int viewWidth = myView.getWidth();

    // Do what you want with the width and height

    ViewTreeObserver obs = myView.getViewTreeObserver();
    obs.removeGlobalOnLayoutListener(this);
   }
  });

Full (better) answer: How to retrieve the dimensions of a view?

score 0 · Answer 3 · answered Mar 09 '12 at 23:27

If you want to drill down to the point that widget have JUST been placed you have to extend each widget you want to monitor. Then override onDraw method and capture if that view has been drawn one time

private boolean imVisible=false;
public boolean imVisible() {
    return imVisible;
}
    @Override
    protected void onDraw(Canvas canvas) {
        if(!imVisible){
            imVisible=true;
        }   
        super.onDraw(canvas);
    }

Then you can do a for loop to the widgets of interest and you know they are drawn at their position with dimentions.

A far better solution is when the onDraw gets called the first time fire a listener that is drawn. You have to set an array of listeners that watch the progress of the widgets. That way the exact moment that the last widget is on the screen... you know it.

When in the Activity life cycle are UI elements available to be measured?

3 Answers3