AndroidUI绘制流程实例2(继承ViewGroup)

案例仅供参考学习。

MainActivity：

package com.example.test;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}
}

TagLayout：

package com.example.test;

import java.util.ArrayList;
import java.util.List;

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

public class TagLayout extends ViewGroup {
	//记录每一行有多高
	List<Integer> lineHeights = new ArrayList<Integer>();
	List<List<View>> views = new ArrayList<List<View>>();
	
	public TagLayout(Context context, AttributeSet attrs) {
		super(context, attrs);
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		views.clear();
		lineHeights.clear();
		//1.计算
		//该行有多少列数据
		List<View> lineViews = new ArrayList<View>();
		int width = getMeasuredWidth();//容器自己的宽度
		int lineWidth = 0;
		int lineHeight = 0;//这一行的最大高度
		int childCount = getChildCount();
		for (int j = 0; j < childCount; j++) {
			View child = getChildAt(j);
			MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
			int childWidth = child.getMeasuredWidth();
			int childHeigh = child.getMeasuredHeight();
			if(childWidth + lp.leftMargin + lp.rightMargin+lineWidth>width){
				//超出,换行
				lineHeights.add(lineHeight);
				views.add(lineViews);
				lineWidth = 0;
				lineViews = new ArrayList<View>();
			}
			lineWidth += childWidth + lp.leftMargin +lp.rightMargin;
			lineHeight = Math.max(lineHeight, childHeigh + lp.topMargin + lp.bottomMargin);
			lineViews.add(child);
		}
		lineHeights.add(lineHeight);
		views.add(lineViews);
		int left = 0;
		int top = 0;
		//2.摆放
		int size = views.size();
		for (int i = 0; i < size; i++) {
			lineViews = views.get(i);
			lineHeight = lineHeights.get(i);
			for (int j = 0; j < lineViews.size(); j++) {
				//遍历这一行的所有child
				View child = lineViews.get(j);
				MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
				int lc = left + lp.leftMargin;
				int tc = top + lp.topMargin;
				int rc = lc + child.getMeasuredWidth();
				int bc = tc + child.getMeasuredHeight();
				child.layout(lc, tc, rc, bc);
				left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
			}
			left = 0;
			top += lineHeight;
		}
	}
	
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
		int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
		int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
		int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
		
		int width = 0;//width=所有行里面最宽的一行
		int height = 0;//height=所有行的高度相加
		//一行的宽度=一行当中的所有view的宽度的和
		int lineWidth = 0;
		int lineHeight = 0;
		
		//1.测量所有子控件的大小
		int childCount = getChildCount();
		for (int i = 0; i < childCount; i++) {
			View child = getChildAt(i);
			measureChild(child, widthMeasureSpec, heightMeasureSpec);
			MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
			//子控件真实占用的宽和高度
			int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
			int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
			//当一行放不下的时候需要换行
			if(lineWidth + childWidth>sizeWidth){
				//换行
				width = Math.max(lineWidth, width);
				lineWidth = childWidth;
				
				height += lineHeight;
				lineHeight = childHeight;
			}else{//累加
				lineWidth +=childWidth;
				lineHeight = Math.max(lineHeight, childHeight);
			}
			//最后一步
			if(i==childCount-1){
				width = Math.max(width, lineWidth);
				height += lineHeight;
			}
		}
		
		//2.测量并定义自身的大小
		int measuredWidth = (modeWidth ==  MeasureSpec.EXACTLY)?sizeWidth:width;//wrap_content/match_parent/EXACTLY
		int measuredHeight = (modeHeight ==  MeasureSpec.EXACTLY)?sizeHeight:height;//wrap_content/match_parent/EXACTLY
		setMeasuredDimension(measuredWidth, measuredHeight);
	}

	@Override
	protected LayoutParams generateLayoutParams(LayoutParams p) {
		// TODO Auto-generated method stub
		return new MarginLayoutParams(p);
	}
	
	@Override
	public LayoutParams generateLayoutParams(AttributeSet attrs) {
		// TODO Auto-generated method stub
		return new MarginLayoutParams(getContext(), attrs);
	}
}

布局:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >
	<com.example.test.TagLayout
	    android:layout_width="match_parent"
	    android:layout_height="wrap_content" >
	
	    <TextView
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:textSize="20dp"
	        android:layout_margin="5dp"
	        android:textColor="#f00"
	        android:background="@drawable/tag_bg"
	        android:text="你好！" />
	    <TextView
	        android:background="@drawable/tag_bg"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:textSize="20dp"
	        android:layout_margin="5dp"
	        android:textColor="#000"
	        android:text="我好！" />
	    <TextView
	        android:background="@drawable/tag_bg"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:textSize="20dp"
	        android:layout_margin="5dp"
	        android:textColor="#f0f"
	        android:text="大家好！" />
	    <TextView
	        android:background="@drawable/tag_bg"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:textSize="20dp"
	        android:layout_margin="5dp"
	        android:textColor="#f0f"
	        android:text="世界好！" />
	    <TextView
	        android:background="@drawable/tag_bg"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:textSize="20dp"
	        android:layout_margin="5dp"
	        android:textColor="#f0f"
	        android:text="Hello World!" />
	    <TextView
	        android:background="@drawable/tag_bg"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:textSize="20dp"
	        android:layout_margin="5dp"
	        android:textColor="#ff0"
	        android:text="Android你好！" />
	</com.example.test.TagLayout>
</LinearLayout>

tag_bg:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <solid android:color="#AAC261"/>
    <corners android:radius="5dp"/>
    <padding android:left="10dp"
        android:top="2dp"
        android:right="10dp"
        android:bottom="2dp" />
</shape>

运行结果: