View_Two_重绘+用代码加载控件_141104

介绍：
1) 自定义绘制一个View控件
2）加载button、image、text、自定义控件View对象
3）通过加载 activity_main 中的 “com.yline.layoutinflatertwo.View.MyViewGroup” 将界面显示出来
文件介绍：
// MainActivity.java 主函数，对应的布局文件为activity_main.xml
// MyView.java 重绘一个自定义View
// MyViewGroup.java 加载 自定义控件、已有控件
// activity_main.xml 主界面，加载MyViewGroup.java
代码：
// MainAvtivity.java

package com.yline.layoutinflatertwo;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.yline.layoutinflatertwo.View.MyViewGroup;

public class MainActivity extends Activity {
	private Button btn;
	private TextView txt;
	private MyViewGroup myViewGroup;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		btn = (Button) findViewById(R.id.btn);
        txt = (TextView)findViewById(R.id.txt);
        myViewGroup = (MyViewGroup)findViewById(R.id.custemViewGroup);
        
        btn.setOnClickListener(new View.OnClickListener() {
			// 设置 其 是否可见
			@Override
			public void onClick(View v) {
				if(txt.getVisibility() == View.VISIBLE)
					txt.setVisibility(View.INVISIBLE);
				else
					txt.setVisibility(View.INVISIBLE);
				
				myViewGroup.invalidate();
				
				if(myViewGroup.getVisibility() == View.VISIBLE)
					myViewGroup.setVisibility(View.GONE);
				else
					myViewGroup.setVisibility(View.VISIBLE);
				
				myViewGroup.requestFocus();
			}
		});
	}
}

// MyView.java

package com.yline.layoutinflatertwo.View;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.view.View;

//自定义View对象
public class MyView extends View{

	private Paint paint  = new Paint() ;
	
	public MyView(Context context) {
		super(context);
	}
	
	public MyView(Context context , AttributeSet attrs){
		super(context,attrs);
	}
	
	/**
	 * //设置该View大小为 50 50
	 */
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
		setMeasuredDimension(50 , 50) ;
	}
	
	//存在canvas对象，即存在默认的显示区域
	@Override
	public void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		
		//加粗
		paint.setTypeface(Typeface.defaultFromStyle(Typeface.BOLD));
		paint.setColor(Color.RED);
		canvas.drawColor(Color.BLUE);
		canvas.drawRect(0, 0, 30, 30, paint);
		canvas.drawText("MyView", 10, 40, paint);
	}
}

// MyViewGroup.java

package com.yline.layoutinflatertwo.View;

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.yline.layoutinflatertwo.R;

//自定义ViewGroup 对象
public class MyViewGroup  extends ViewGroup{

	private static String TAG = "MyViewGroup" ;
	private Context mContext ;
	
	public MyViewGroup(Context context) {
		super(context);
		mContext = context ;
		init() ;
	}

	//xml定义的属性,需要该构造函数
    public MyViewGroup(Context context , AttributeSet attrs){
    	super(context,attrs);
    	mContext = context;
    	init();
    }
	
    //为MyViewGroup添加三个子View
    private void init(){
    	//调用ViewGroup父类addView()方法添加子View
    	
    	//child 对象一 ： Button
    	Button btn= new Button(mContext);
    	btn.setText("I am Button");
    	this.addView(btn);
    	
    	//child 对象二 : ImageView 
    	ImageView img = new ImageView(mContext);
    	img.setBackgroundResource(R.drawable.ic_launcher);
    	this.addView(img) ;
    	
    	//child 对象三 : TextView
    	TextView txt = new TextView(mContext);
    	txt.setText("Only Text");
    	this.addView(txt) ; 
    	
    	//child 对象四 ： 自定义View
    	MyView myView = new MyView(mContext) ;
    	this.addView(myView) ; 
    }
    
    /**
     * 对每个子View进行measure():设置每子View的大小，即实际宽和高
     * 接收两个参数，
     * widthMeasureSpec   实际宽度
     * heightMeasureSpec  实际高度
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
    	int childCount = getChildCount();  // ViewGroup 的大小
    	
    	int specSize_Widht = MeasureSpec.getSize(widthMeasureSpec);   // 获取实际的宽度
    	int specSize_Heigth = MeasureSpec.getSize(heightMeasureSpec);  // 获取实际的高度
    	
    	setMeasuredDimension(specSize_Widht,specSize_Heigth); //设置本ViewGroup的宽高
    	
    	for(int i=0 ;i<childCount ; i++){
    		View child = getChildAt(i) ;   //获得每个对象的引用
    		child.measure(50, 50) ;   //简单的设置每个子View对象的宽高为 50px , 50px  
    		//或者可以调用ViewGroup父类方法measureChild()或者measureChildWithMargins()方法
    	    this.measureChild(child, widthMeasureSpec, heightMeasureSpec) ;
    	}
    }
    
    /**
     * 对每个子View视图进行布局
     * 接收四个参数，分别代表着左、上、右、下的坐标
     */
	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
    	int childCount = getChildCount() ;
    	
    	int startLeft = 0 ;//设置每个子View的起始横坐标 
    	int startTop = 10 ; //每个子View距离父视图的位置 ， 简单设置为10px吧 。 可以理解为 android:margin=10px ;
    	
    	// 一次绘制一个子视图
    	for(int i=0 ;i<childCount ; i++){
    		View child = getChildAt(i) ;   //获得每个对象的引用
    		child.layout(startLeft, startTop,
    				startLeft+child.getMeasuredWidth(), startTop+child.getMeasuredHeight()) ;
    		startLeft = startLeft+child.getMeasuredWidth() + 10;  //校准startLeft值，View之间的间距设为10px ;
    	}   	   	
	}
	
	/**
	 * 绘图过程Android已经为我们封装好了 ,这儿只为了观察方法调用线程
	 */
	protected void dispatchDraw(Canvas canvas){
		Log.i(TAG, "**** dispatchDraw start ****") ;
		
		super.dispatchDraw(canvas) ;
	}
    
	protected boolean drawChild(Canvas canvas , View child, long drawingTime){
		Log.i(TAG, "**** drawChild start ****") ;
		
		return super.drawChild(canvas, child, drawingTime) ;
	}
}

// activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/txt"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button
        android:id="@+id/btn"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20px"
        android:text="点击我查看Log绘制流程" >
    </Button>
    
    <com.yline.layoutinflatertwo.View.MyViewGroup
        android:id="@+id/custemViewGroup"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >
    </com.yline.layoutinflatertwo.View.MyViewGroup>

</LinearLayout>

运行图：



可运行代码下载链接：
http://pan.baidu.com/s/1sjI2wRN

参考网址：
/article/1562126.html