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