Views inside a custom ViewGroup not rendering after a size change

Question

I\'m running into a problem that has me stumped and I was hoping someone could give me some pointers.

I\'m working on an application that uses a custom ViewGroup (ac

Answer 1

I run into the same problem.

My onMeasure() was something like this:

@Override    
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        ...
        //calculate new width and height here
        ...
        setMeasuredDimension(newMeasureSpecWidth, newMeasureSpecHeight);
    }

My mistake was that I was calling super.onMeasure() on the first line of onMeasure(), so the inner children of my ViewGroup were being calculated based on a size that was about to change.

So my fix was doing something like this:

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    ...
    //calculate new width and height here
    ...
    int newMeasureSpecWidth = MeasureSpec.makeMeasureSpec(newWidth, MeasureSpec.EXACTLY);
    int newMeasureSpecHeight = MeasureSpec.makeMeasureSpec(newHeight, MeasureSpec.EXACTLY);
    super.onMeasure(newMeasureSpecWidth, newMeasureSpecHeight);
}

So I was setting the new size to my ViewGroup using the call to super.onMeasure(), and then it is also communicating the new size to its children.

Remember: the contract when you override onMeasure() is that you have to call setMeasuredDimension() (and you can achieve this by calling the method itself or by calling super.onMeasure())

Answer 2

It's not a hack, it's how it's supposed to work. onSizeChanged() is invoked as part of the layout pass, and you cannot/should not requestLayout() during a layout pass. It is correct to post a requestLayout() on the event queue to indicate that you have changed the View hierarchy during a layout pass.