Android自定义ViewGroup的实现方法

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="CascadeViewGroup">
  <attr name="verticalspacing" format="dimension"/>
  <attr name="horizontalspacing" format="dimension"/>
 </declare-styleable>

 <declare-styleable name="CascadeViewGroup_LayoutParams">
  <attr name="layout_paddingleft" format="dimension"/>
  <attr name="layout_paddinTop" format="dimension"/>
 </declare-styleable>
</resources>

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <dimen name="default_horizontal_spacing">10dp</dimen>
 <dimen name="default_vertical_spacing">10dp</dimen>
</resources>

package com.app.CustomViewMotion;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by charles on 2015/8/13.
 */
public class CascadeViewGroup extends ViewGroup {

 //自定义布局中设置的宽度和高度
 private int mHoriztonalSpacing;
 private int mVerticalSpacing;

 public CascadeViewGroup(Context context) {
  this(context, null);
 }

 public CascadeViewGroup(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 public CascadeViewGroup(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CascadeViewGroup);
  try {
   //获取设置的宽度
   mHoriztonalSpacing = a.getDimensionPixelSize(R.styleable.CascadeViewGroup_horizontalspacing,
     this.getResources().getDimensionPixelSize(R.dimen.default_horizontal_spacing));
   //获取设置的高度
   mVerticalSpacing = a.getDimensionPixelSize(R.styleable.CascadeViewGroup_verticalspacing,
     this.getResources().getDimensionPixelSize(R.dimen.default_vertical_spacing));

  } catch (Exception e) {
   e.printStackTrace();

  } finally {
   a.recycle();
  }
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  final int count = this.getChildCount();
  int width = this.getPaddingLeft();
  int height = this.getPaddingTop();
  for (int i = 0; i < count; i++) {
   final View currentView = this.getChildAt(i);
   this.measureChild(currentView, widthMeasureSpec, heightMeasureSpec);
   CascadeViewGroup.LayoutParams lp = (CascadeViewGroup.LayoutParams) currentView.getLayoutParams();
   if(lp.mSettingPaddingLeft != 0){
    width +=lp.mSettingPaddingLeft;
   }
   if(lp.mSettingPaddingTop != 0){
    height +=lp.mSettingPaddingTop;
   }
   lp.x = width;
   lp.y = height;
   width += mHoriztonalSpacing;
   height += mVerticalSpacing;
  }
  width +=getChildAt(this.getChildCount() - 1).getMeasuredWidth() + this.getPaddingRight();
  height += getChildAt(this.getChildCount() - 1).getMeasuredHeight() + this.getPaddingBottom();
  this.setMeasuredDimension(resolveSize(width, widthMeasureSpec), resolveSize(height, heightMeasureSpec));

 }

 @Override
 protected void onLayout(boolean b, int l, int i1, int i2, int i3) {
  final int count = this.getChildCount();
  for (int i = 0; i < count; i++) {
   final View currentView = this.getChildAt(i);
   CascadeViewGroup.LayoutParams lp = (CascadeViewGroup.LayoutParams) currentView.getLayoutParams();
   currentView.layout(lp.x, lp.y, lp.x + currentView.getMeasuredWidth(),
     lp.y + currentView.getMeasuredHeight());
  }


 }

 public static class LayoutParams extends ViewGroup.LayoutParams {
  int x;
  int y;
  int mSettingPaddingLeft;
  int mSettingPaddingTop;

  public LayoutParams(Context c, AttributeSet attrs) {
   super(c, attrs);
   TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.CascadeViewGroup_LayoutParams);
   mSettingPaddingLeft = a.getDimensionPixelSize(R.styleable.CascadeViewGroup_LayoutParams_layout_paddingleft, 0);
   mSettingPaddingTop = a.getDimensionPixelSize(R.styleable.CascadeViewGroup_LayoutParams_layout_paddinTop, 0);
   a.recycle();
  }

  public LayoutParams(int width, int height) {
   super(width, height);
  }

  public LayoutParams(ViewGroup.LayoutParams source) {
   super(source);
  }
 }

 @Override
 protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
  return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
 }

 @Override
 protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
  return new LayoutParams(p);
 }

 @Override
 public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {
  return new LayoutParams(this.getContext(), attrs);
 }
}

<?xml version="1.0" encoding="utf-8"?>
<!--添加自定义属性给viewGroup-->
<!--新添加的命名空间的后缀必须保持和.xml中声明的包名一致-->
<com.app.CustomViewMotion.CascadeViewGroup
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:ts="http://schemas.android.com/apk/res/com.app.CustomViewMotion"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  ts:horizontalspacing="15dp"
  ts:verticalspacing="15dp">

 <TextView android:layout_width="100dp"
    android:layout_height="100dp"
    android:gravity="center"
    android:text="text1"
    android:background="#668B8B"/>

 <TextView android:layout_width="100dp"
    android:layout_height="100dp"
    android:gravity="center"
    android:text="text2"
    android:background="#FFDAB9"/>

 <TextView android:layout_width="100dp"
    android:layout_height="100dp"
    android:gravity="center"
    android:text="text3"
    android:background="#43CD80"/>

<!--这个子view中添加自定义子view属性-->
 <TextView android:layout_width="100dp"
    android:layout_height="100dp"
    android:gravity="center"
    android:text="text4"
    ts:layout_paddingleft="100dp"
    ts:layout_paddinTop="100dp"
    android:background="#00CED1"/>
</com.app.CustomViewMotion.CascadeViewGroup>