通过重写ViewGroup学习onMeasure()
onLayout()方法
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//获取模式和大小，边界参数共有3种模式：UNSPECIFIED一般为0, EXACTLY准确尺寸, AT_MOST自适应尺寸
int w_mode = MeasureSpec.getMode(widthMeasureSpec);
int w_size = MeasureSpec.getSize(widthMeasureSpec);
int h_mode = MeasureSpec.getMode(heightMeasureSpec);
int h_size = MeasureSpec.getSize(heightMeasureSpec);
//计算自定义的所有子控件的大小
measureChildren(widthMeasureSpec, heightMeasureSpec);
//通知父控件，宽高需要多大地方放置子控件
//setMeasuredDimension(resolveSize(size, widthMeasureSpec),resolveSize(size, heightMeasureSpec));
setMeasuredDimension(w_size, h_size);
Log.e("onMeasure","宽mode=" + w_mode + "宽size="+ w_size
+ "高mode=" + h_mode+ "高size=" +h_size);
// super.onMeasure(widthMeasureSpec,heightMeasureSpec);
}
//onLayout是为了指定视图的显示位置，方法执行的前后顺序是在onMeasure之后，因为视图肯定是只有知道大小才能指定位置放置
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// 记录总高度
int mTotalHeight = 0;
// 遍历所有子视图
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View childView = getChildAt(i);
// 获取在onMeasure中计算的视图尺寸
int measureHeight = childView.getMeasuredHeight();
int measuredWidth = childView.getMeasuredWidth();
childView.layout(l, mTotalHeight, measuredWidth, mTotalHeight + measureHeight);
mTotalHeight += measureHeight;
}
}快速了解Android onMeasure() onLayout()
原文：http://blog.csdn.net/a704755096/article/details/46546969
