viewgroup 渲染过程

参考

http://blog.csdn.net/luoshengyang/article/details/8372924

总体步骤 performTraversals-->measure---->layout----->draw   测量布局渲染

1.measure 测量过程

例子：FrameLayout

measure

测量开始判读是否需要测量

onMeasure

求实际宽度 measureChild调用子布局的 measure方法测量子布局大小，setMeasuredDimension，resolveSize设置布局大小

public static int resolveSize(int size, int measureSpec) {  int result = size;  int specMode = MeasureSpec.getMode(measureSpec);  int specSize =  MeasureSpec.getSize(measureSpec);  switch (specMode) {  case MeasureSpec.UNSPECIFIED:  result = size;  break;  case MeasureSpec.AT_MOST:  result = Math.min(size, specSize);  break;  case MeasureSpec.EXACTLY:  result = specSize;  break;  }  return result;  }  

　　

2.layout

layout

onlayout

child.layout

3.draw

draw

draw blackgroud

onDraw

dispatchDraw

drawChild