原理：
其实很简单，Measure Layout。只需要这两个步骤就可以搞定了。完全的手动去Measure Layout。
我们看一下代码。
解释就在代码里面做注释了，因为使用为知笔记写的博客，格式不符合代码格式。大家可以看具体的源码。最后又源码下载地址。
1.Measure 测量
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int lineHeight = 0 ;
int lineWidth = 0 ;
int width = 0 ;
int height = 0 ;
int childCount = getChildCount();
Log.i("Test", getPaddingLeft() + "==right=" +getPaddingRight());
for (int i = 0; i < childCount; i++) {
View childView = getChildAt(i);
measureChild(childView, widthMeasureSpec, heightMeasureSpec);
MarginLayoutParams params = (MarginLayoutParams) childView.getLayoutParams();
int childWidth = childView.getMeasuredWidth() + params.leftMargin + params.rightMargin ;
int childHeight = childView.getMeasuredHeight() + params.topMargin + params.bottomMargin ;
if ((lineWidth + childWidth ) > widthSize - getPaddingLeft() - getPaddingRight() ) {
width = Math.max(width, lineWidth);
lineWidth = childWidth ;
height += lineHeight ;
lineHeight = childHeight;
}else {
lineWidth += childWidth ;
lineHeight = Math.max(lineHeight, childHeight);
}
if (i == childCount-1) {
width = Math.max(width, lineWidth);
height += lineHeight ;
}
}
height += getPaddingTop() + getPaddingBottom() ;
setMeasuredDimension(widthMode == MeasureSpec.EXACTLY?widthSize:width,
heightMode == MeasureSpec.EXACTLY?heightSize:height);
} @Override
protected void onLayout(boolean a, int l, int t, int r, int b) {
childViewList.clear();
int childCount = getChildCount() ;
int width = getWidth();
int lineWidth = 0 ;
int lineHeight = 0 ;
List<View> lineViews = new ArrayList<View>();
for (int i = 0; i < childCount; i++) {
View childView = getChildAt(i);
MarginLayoutParams params = (MarginLayoutParams) childView.getLayoutParams();
int childWidth = childView.getMeasuredWidth() + params.leftMargin + params.rightMargin ;
int childHeight = childView.getMeasuredHeight() + params.topMargin + params.bottomMargin ;
if (lineWidth + childWidth > width - getPaddingLeft() - getPaddingRight()) {
childViewList.add(lineViews);
lineViews = new ArrayList<View>();
if (i == 0 ) {
lineHeight += getPaddingTop() ;
}else if (i== childCount - 1) {
lineHeight += getPaddingBottom() ;
}
this.lineHeight.add(lineHeight);
lineHeight = 0 ;
lineWidth = 0 ;
}
lineWidth += childWidth;
lineHeight = Math.max(lineHeight, childHeight) ;
lineViews.add(childView);
}
childViewList.add(lineViews);
this.lineHeight.add(lineHeight);
int left = getPaddingLeft() ;
int top = getPaddingTop();
for (int i = 0; i < childViewList.size(); i++) {
lineViews = childViewList.get(i);
for (int j = 0; j < lineViews.size(); j++) {
View childView = lineViews.get(j);
MarginLayoutParams params = (MarginLayoutParams) childView.getLayoutParams();
int lc = left + params.leftMargin ;
int tc = top + params.topMargin ;
int rc = lc + childView.getMeasuredWidth() ;
int bc = tc + childView.getMeasuredHeight() ;
childView.layout(lc,tc,rc,bc);
left += params.leftMargin + childView.getMeasuredWidth() + params.rightMargin ;
}
left = getPaddingLeft() ;
top += this.lineHeight.get(i) ;
}
}
代码下载地址：
