How to get Custom ViewGroup height in onMeasure

Question

This is onMeasure() on CustomView which extend FrameLayout. After investigate onMeasure(), heigh size is always zero. How could I know what is the height size of this CustomView to manipulate child view later.

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

            int viewHeightMode = MeasureSpec.getMode(heightMeasureSpec);
            int viewWidthMode = MeasureSpec.getMode(widthMeasureSpec);
            int viewHeight = MeasureSpec.getSize(heightMeasureSpec);
            int viewWidth = MeasureSpec.getSize(widthMeasureSpec);
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

Answer 1

First of all please read this question. It is about measuring of View.

Main difference about ViewGroup that you should measure in your code all your childs.

for(int i=0; i<getChildCount(); i++) {
    View child = getChildAt(i);
    LayoutParams lp = child.getLayoutParams();
    int widthMeasureMode = lp.width == LayoutParams.WRAP_CONTENT ? MeasureSpec.AT_MOST : MeasureSpec.EXACTLY,
        heightMeasureMode = lp.height == LayoutParams.WRAP_CONTENT ? MeasureSpec.AT_MOST : MeasureSpec.EXACTLY;
    int widthMeasure = MeasureSpec.makeMeasureSpec(getWidth() - left, widthMeasureMode),
        heightMeasure = MeasureSpec.makeMeasureSpec(getHeight() - top, heightMeasureMode);
    child.measure(widthMeasure, heightMeasure);
    int childWidth = child.getMeasuredWidth(),
        childHeight = child.getMeasuredHeight();
    //make something with that
}

That shows how to get size of all childs. May be you want to calculate sum of heights, may be just find maximum value - it is your own goal.

By the way. If your base class is not ViewGroup, but FrameLayout for example, measuring childs could be done in onLayout method. In this case in your onMeasure method you can do nothing about measuring childs - just take sizes. But it is just a guess - better to check that.