public class CustomViewGroup extends ViewGroup {
public static class LayoutParams extends ViewGroup.MarginLayoutParams {
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
}
}
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new CustomViewGroup.LayoutParams(getContext(), attrs);
}
}
这样修改之后，我们就可以在onLayout()函数中获取子控件的layout_margin值了，添加了layout_margin的onLayout()函数实现如下所示：
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
int mViewGroupWidth = getMeasuredWidth(); //当前ViewGroup的总宽度
int mViewGroupHeight = getMeasuredHeight(); //当前ViewGroup的总高度
int mPainterPosX = left; //当前绘图光标横坐标位置
int mPainterPosY = top; //当前绘图光标纵坐标位置
int childCount = getChildCount();
for ( int i = 0; i < childCount; i++ ) {
View childView = getChildAt(i);
int width = childView.getMeasuredWidth();
int height = childView.getMeasuredHeight();
CustomViewGroup.LayoutParams margins = (CustomViewGroup.LayoutParams)(childView.getLayoutParams());
//ChildView占用的width = width+leftMargin+rightMargin
//ChildView占用的height = height+topMargin+bottomMargin
//如果剩余的空间不够，则移到下一行开始位置
if( mPainterPosX + width + margins.leftMargin + margins.rightMargin > mViewGroupWidth ) {
mPainterPosX = left;
mPainterPosY += height + margins.topMargin + margins.bottomMargin;
}
//执行ChildView的绘制
childView.layout(mPainterPosX+margins.leftMargin, mPainterPosY+margins.topMargin,mPainterPosX+margins.leftMargin+width, mPainterPosY+margins.topMargin+height);
mPainterPosX += width + margins.leftMargin + margins.rightMargin;
}
}
6. 总结
费了好大劲，终于算是把自定义ViewGroup的onLayout()相关知识点讲清楚了，如果有任何疑问欢迎留言或者来信lujun.hust@gmail.com交流，如果喜欢本文欢迎转载，但希望能尊重我的劳动成果，给出本文文链接，谢谢。
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