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