layout - How to size an Android view based on its parent's dimensions

Question

How can I size a view based on the size of its parent layout. For example I have a RelativeLayout that fills the full screen, and I want a child view, say an ImageView, to take up the whole height, and 1/2 the width?

I've tried overriding all on onMeasure, onLayout, onSizeChanged, etc and I couldn't get it to work....

Answer 1

I don't know if anyone is still reading this thread or not, but Jeff's solution will only get you halfway there (kinda literally). What his onMeasure will do is display half the image in half the parent. The problem is that calling super.onMeasure prior to the setMeasuredDimension will measure all the children in the view based on the original size, then just cut the view in half when the setMeasuredDimension resizes it.

Instead, you need to call setMeasuredDimension (as required for an onMeasure override) and provide a new LayoutParams for your view, then call super.onMeasure. Remember, your LayoutParams are derived from your view's parent type, not your view's type.

@Override 
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
   int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
   int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
   this.setMeasuredDimension(parentWidth/2, parentHeight);
   this.setLayoutParams(new *ParentLayoutType*.LayoutParams(parentWidth/2,parentHeight));
   super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

I believe the only time you'll have problems with the parent LayoutParams is if the parent is an AbsoluteLayout (which is deprecated but still sometimes useful).