protected void onSizeChanged(
int w,
int h,
int oldw,
int oldh)
protected void onMeasure(
int widthMeasure,
int heightMeasure)
首先onSizeChanged是设置大小的，而onMeasure是为了能够设置wrap_content或者是match_parent的属性。因此，如果我们希望自定义的View能够使用wrap_content或者是match_parent的属性，应该写成如下形式：
@Override
protected void onMeasure(
int widthMeasure,
int heightMeasure){
super.onMeasure(widthMeasure, heightMeasure);
setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth());
}
