自定义View
onMeasure
MeasureSpec 32位 前两位代表mode,后30位表示size
MeasureSpec.getMode/getSize
MeasureSpec.makeMeasureSpec
mode: EXACTLY AT_MOST UNSPECIFIED
onMeasure(调用setMeasuredDimension(调用getDefaultSize(调用getSuggestedMininum())))
onLayout
viewgroup
onDraw
canvas paint