<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 android:id="@+id/frameLayout1" 
 android:orientation="vertical" 
 > 
  
</FrameLayout> 

package com.example.test; 
 
import android.app.Activity; 
import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.BitmapShader; 
import android.graphics.Canvas; 
import android.graphics.Matrix; 
import android.graphics.Shader.TileMode; 
import android.graphics.drawable.ShapeDrawable; 
import android.graphics.drawable.shapes.OvalShape; 
import android.os.Bundle; 
import android.view.MotionEvent; 
import android.view.View; 
import android.widget.FrameLayout; 
 
public class MainActivity extends Activity { 
 
 
 @Override 
 public void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.main); 
  
  //獲取布局文件中添加的幀布局管理器 
  FrameLayout fl=(FrameLayout)findViewById(R.id.frameLayout1); 
  //將自定義的MyView視圖添加到幀布局 
  fl.addView(new MyView(this)); 
 } 
  
 public class MyView extends View{ 
  private Bitmap bitmap;//源圖像，也就是背景圖像 
  private ShapeDrawable drawable; 
  private final int RADIUS=57;//放大鏡的半徑 
  private final int FACTOR=2;//放大倍數(shù) 
  private Matrix matrix=new Matrix(); 
  private Bitmap bitmap_magnifiter;//放大鏡位圖 
  private int m_left=0;//放大鏡的左邊距 
  private int m_top=0;//放大鏡的頂邊距 
   
  public MyView(Context context) { 
   super(context); 
    
   //獲取要顯示的源圖像 
   Bitmap bitmap_source=BitmapFactory.decodeResource(getResources(), R.drawable.backgroud); 
   bitmap=bitmap_source; 
   BitmapShader shader=new BitmapShader(Bitmap.createScaledBitmap( 
     bitmap_source, bitmap_source.getWidth()*FACTOR, 
     bitmap_source.getHeight()*FACTOR, true),TileMode.CLAMP, 
     TileMode.CLAMP);//創(chuàng)建BitmapShader對(duì)象 
   /* 注：Bitmap.createScaledBitmap() 方 法根據(jù)給定的 Bitmap 創(chuàng)建 一個(gè)新的，縮放后的 Bitmap。 
    * Shader.TileMode類型的參數(shù)包括CLAMP、MIRROR和REPEAT3個(gè)可選值，其中，CLAMP為使用 
    * 邊界顏色來填充剩余的空間；MIRROR為采用鏡像方式；REPEAT為采用重復(fù)方式*/ 
    
   //圓形的drawable 
   drawable=new ShapeDrawable(new OvalShape()); 
   drawable.getPaint().setShader(shader); 
   drawable.setBounds(0, 0, RADIUS*2, RADIUS*2);//設(shè)置圓的外切矩形 
   bitmap_magnifiter=BitmapFactory.decodeResource(getResources(), 
     R.drawable.magnifiter);//獲取放大鏡圖像 
   m_left=RADIUS-bitmap_magnifiter.getWidth()/2;//計(jì)算放大鏡默認(rèn)的左邊距 
   m_top=RADIUS-bitmap_magnifiter.getHeight()/2;//計(jì)算放大鏡默認(rèn)的右邊距 
  } 
 
 
  @Override 
  protected void onDraw(Canvas canvas) { 
   canvas.drawBitmap(bitmap, 0,0, null);//繪制背景圖像 
   canvas.drawBitmap(bitmap_magnifiter, m_left, m_top,null);//繪制放大鏡圖像 
   drawable.draw(canvas);//繪制放大后的圖像 
   super.onDraw(canvas); 
  } 
 
 
  //重寫onTouchEvent方法實(shí)現(xiàn)當(dāng)用戶觸摸屏幕時(shí)，放大觸摸點(diǎn)附近的圖像 
  @Override 
  public boolean onTouchEvent(MotionEvent event) { 
   final int x=(int)event.getX(); 
   final int y=(int)event.getY(); 
   //平移到繪制shader的起始位置 
   matrix.setTranslate(RADIUS-x*FACTOR, RADIUS-y*FACTOR); 
   drawable.getPaint().getShader().setLocalMatrix(matrix); 
   drawable.setBounds(x-RADIUS,y-RADIUS,x+RADIUS,y+RADIUS);//設(shè)置圓的外切矩形 
   m_left=x-bitmap_magnifiter.getWidth()/2;//計(jì)算放大鏡的左邊距 
   m_top=y-bitmap_magnifiter.getHeight()/2;//計(jì)算放大鏡的右邊距 
   invalidate();//重繪畫布 
    
   return true; 
  } 
   
   
 } 
}