Android自定义控件

Question

android自定义控件中  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {//        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        setMeasuredDimension(backgroundBitmap.getWidth(), backgroundBitmap.getHeight());//为什么要用这个方法保存数据    }