package com.weidingqiang.testviewb;import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;/*** Created by weidingqiang on 15/11/19.*/
public class BaViewGroup extends ViewGroup {public BaViewGroup(Context context) {this(context,null);}public BaViewGroup(Context context, AttributeSet attrs) {super(context, attrs);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
/*** 获得此ViewGroup上级容器为其推荐的宽和高，以及计算模式*/int widthMode = MeasureSpec.getMode(widthMeasureSpec);int heightMode = MeasureSpec.getMode(heightMeasureSpec);int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);// 计算出所有的childView的宽和高
        measureChildren(widthMeasureSpec, heightMeasureSpec);/*** 记录如果是wrap_content是设置的宽和高*/int width = 0;int height = 0;int cCount = getChildCount();int cWidth = 0;int cHeight = 0;MarginLayoutParams cParams = null;// 用于计算左边两个childView的高度int lHeight = 0;// 用于计算右边两个childView的高度，最终高度取二者之间大值int rHeight = 0;// 用于计算上边两个childView的宽度int tWidth = 0;// 用于计算下面两个childiew的宽度，最终宽度取二者之间大值int bWidth = 0;/*** 根据childView计算的出的宽和高，以及设置的margin计算容器的宽和高，主要用于容器是warp_content时*/for (int i = 0; i < cCount; i++){View childView = getChildAt(i);cWidth = childView.getMeasuredWidth();cHeight = childView.getMeasuredHeight();cParams = (MarginLayoutParams) childView.getLayoutParams();// 上面两个childViewif (i == 0 || i == 1){tWidth += cWidth + cParams.leftMargin + cParams.rightMargin;}if (i == 2 || i == 3){bWidth += cWidth + cParams.leftMargin + cParams.rightMargin;}if (i == 0 || i == 2){lHeight += cHeight + cParams.topMargin + cParams.bottomMargin;}if (i == 1 || i == 3){rHeight += cHeight + cParams.topMargin + cParams.bottomMargin;}}width = Math.max(tWidth, bWidth);height = Math.max(lHeight, rHeight);/*** 如果是wrap_content设置为我们计算的值* 否则：直接设置为父容器计算的值*/setMeasuredDimension((widthMode == MeasureSpec.EXACTLY) ? sizeWidth: width, (heightMode == MeasureSpec.EXACTLY) ? sizeHeight: height);}@Overrideprotected void onLayout(boolean changed, int l, int t, int r, int b) {int cCount = getChildCount();int cWidth = 0;int cHeight = 0;MarginLayoutParams cParams = null;/*** 遍历所有childView根据其宽和高，以及margin进行布局*/for (int i = 0; i < cCount; i++){View childView = getChildAt(i);cWidth = childView.getMeasuredWidth();cHeight = childView.getMeasuredHeight();cParams = (MarginLayoutParams) childView.getLayoutParams();int cl = 0, ct = 0, cr = 0, cb = 0;switch (i){case 0:cl = cParams.leftMargin;ct = cParams.topMargin;break;case 1:cl = getWidth() - cWidth - cParams.leftMargin- cParams.rightMargin;ct = cParams.topMargin;break;case 2:cl = cParams.leftMargin;ct = getHeight() - cHeight - cParams.bottomMargin;break;case 3:cl = getWidth() - cWidth - cParams.leftMargin- cParams.rightMargin;ct = getHeight() - cHeight - cParams.bottomMargin;break;}cr = cl + cWidth;cb = cHeight + ct;childView.layout(cl, ct, cr, cb);}}@Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {super.onSizeChanged(w, h, oldw, oldh);}@Overridepublic ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs){return new MarginLayoutParams(getContext(), attrs);}
}

<com.weidingqiang.testviewb.BaViewGroupandroid:layout_width="300dp"android:layout_height="300dp"android:background="#ff0"><TextViewandroid:layout_width="50dp"android:layout_height="50dp"android:background="#FF4444"android:gravity="center"android:text="0"android:textColor="#FFFFFF"android:textSize="22sp"android:textStyle="bold" /><TextViewandroid:layout_width="50dp"android:layout_height="50dp"android:background="#00ff00"android:gravity="center"android:text="1"android:textColor="#FFFFFF"android:textSize="22sp"android:textStyle="bold" /><TextViewandroid:layout_width="50dp"android:layout_height="50dp"android:background="#ff0000"android:gravity="center"android:text="2"android:textColor="#FFFFFF"android:textSize="22sp"android:textStyle="bold" /><TextViewandroid:layout_width="50dp"android:layout_height="50dp"android:background="#0000ff"android:gravity="center"android:text="3"android:textColor="#FFFFFF"android:textSize="22sp"android:textStyle="bold" /></com.weidingqiang.testviewb.BaViewGroup>