1，引言：刚从国庆长假的放荡中醒过来，已经有将近十天没碰电脑了，上午写写代码感觉手还是挺生的，想把自定义view好好的系统的学学，在网上看了看别人出的教程 ，stay4it的自定义view感觉还是挺好的，就打算按照这个课程好好学习学习。并打算用blog记录下来（主要怕自己忘记嘛）
2， 今天这个简单的自定义view是在网上看的，就是实现其内所有的view放置在上下左右的顺序进行排列，然后简单的跟着别人的思路写了些，效果图如下：
不多说了 直接上代码 ，主要是重写了OnMeasure（）和OnDraw（）方法
MyFourTextViewGroup.Class
package com.wangjitao.myview.view;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
/**
* Created by wangjitao on 2016/10/8 0008.
* 当内部传入TextView的时候依次显示在上下左右的四个角
*/
public class MyFourTextViewGroup extends ViewGroup {
public MyFourTextViewGroup(Context context) {
super(context);
}
public MyFourTextViewGroup(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyFourTextViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
/**
* 1,重写generateLayoutParams是view支持margin
*
* @param attrs
* @return
*/
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MarginLayoutParams(getContext(), attrs);
}
/**
* 计算所有子view的宽度和高度，根据ChildView的计算解雇，设置自己的宽和高
*
* @param widthMeasureSpec
* @param heightMeasureSpec
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
/**
* 获得此viewGroup上级容器为其推荐的高和宽，以及计算的方式
*/
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
//计算出所有的childView的设置的宽和高
measureChildren(widthMeasureSpec, heightMeasureSpec);
/**
* 记录如果是wrap_content设置的宽和高
*/
int width = 0;
int height = 0;
int childCount = getChildCount();
int childWidth = 0;
int childHeight = 0;
MarginLayoutParams childParams = null;
//用于计算左边两个childView的高度
int leftHeight = 0;
//用于计算右边两个childView的高度,最终高度取二者之间的最大值
int rightHeight = 0;
//用于取上面两个childView的宽度
int topWidth = 0;
//计算下面两个chideView的宽高，取二者之间的最大值
int bottomWidth = 0;
/**
* 根据childView计算出来的宽度和高度，以及设置的margin计算容器的宽和高，主要用于容器的wrap_content
*/
for (int i = 0; i < childCount; i++) {
View childView = getChildAt(i);
childWidth = childView.getMeasuredWidth();
childHeight = childView.getMeasuredHeight();
childParams = (MarginLayoutParams) childView.getLayoutParams();
//上面的两个Childview比较的是宽度
if (i == 0 || i == 1) {
topWidth += childWidth + childParams.leftMargin + childParams.rightMargin;
}
if (i == 2 || i == 3) {
bottomWidth += childWidth + childParams.leftMargin + childParams.rightMargin;
}
//左边的两个childView比较的是高度
if (i == 0 || i == 2) {
leftHeight += childHeight + childParams.topMargin + childParams.bottomMargin;
}
if (i == 0 || i == 2) {
rightHeight += childHeight + childParams.topMargin + childParams.bottomMargin;
}
}
width = Math.max(topWidth, bottomWidth);
height = Math.max(leftHeight, rightHeight);
//如果是wrap_content则设置为我们计算的值，否的话则设置为父容器计算的值
setMeasuredDimension((widthMode == MeasureSpec.EXACTLY) ? widthSize : width,
(heightMode == MeasureSpec.EXACTLY) ? heightSize : height);
}
/**
* 用来给所有的childView进行定位
*/
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
int childCount = getChildCount();
int childWidth = 0;
int childHeight = 0;
MarginLayoutParams childParams = null;
/**
* 遍历所有childView根据其高和宽，以及margin进行布局
*/
for (int i = 0; i < childCount; i++) {
View childView = getChildAt(i);
childWidth = childView.getMeasuredWidth();
childHeight = childView.getMeasuredHeight();
childParams = (MarginLayoutParams) childView.getLayoutParams();
int childLeft = 0;
int childTop = 0;
int childRight = 0;
int childBottom = 0;
switch (i) {
case 0:
childLeft = childParams.leftMargin;
childTop = childParams.topMargin;
break;
case 1:
Log.i("wangjitao", "getWidth():" + getWidth() + ",childWidth :" + childWidth
+ ",childParams.leftMargin:" + childParams.leftMargin);
childLeft = getWidth() - childWidth -
childParams.leftMargin - childParams.rightMargin;
childTop = childParams.topMargin;
break;
case 2:
childLeft = childParams.leftMargin;
childTop = getHeight() - childHeight - childParams.bottomMargin;
break;
case 3:
childLeft = getWidth() - childWidth -
childParams.leftMargin - childParams.rightMargin;
childTop = getHeight() - childHeight - childParams.bottomMargin;
break;
}
childRight = childLeft + childWidth;
childBottom = childHeight + childTop;
childView.layout(childLeft, childTop, childRight, childBottom);
}
}
}