http://blog.csdn.net/hanghangaidoudou/article/details/6436048

Android实现图片放大缩小   

package com.min.Test_Gallery;  
 
import Android.app.Activity;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.graphics.Color;  
import android.graphics.Matrix;  
import android.os.Bundle;  
import android.util.DisplayMetrics;  
import android.util.Log;  
import android.view.GestureDetector;  
import android.view.KeyEvent;  
import android.view.MotionEvent;  
import android.view.View;  
import android.view.GestureDetector.OnGestureListener;  
import android.view.View.OnTouchListener;  
import android.widget.Button;  
import android.widget.FrameLayout;  
import android.widget.ImageView;  
import android.widget.LinearLayout;  
import android.widget.Toast;  
 
public class DisplayImage extends Activity implements OnTouchListener, OnGestureListener  {  
    private static final String TAG = "DisplayImage";  
    private static final int FLING_MIN_DISTANCE = 100;  
    private static final int FLING_MIN_VELOCITY = 200;  
      
      
    /* 相关变量声明 */ 
    private ImageView mImageView;  
    private Button mButton01;  
    private Button mButton02;  
    private FrameLayout layout1;  
    private LinearLayout layoutImage;  
    private Bitmap bmp;  
    private int id=0;  
    private int displayWidth;  
    private int displayHeight;  
    private float scaleWidth=1;  
    private float scaleHeight=1;  
    private GestureDetector mGestureDetector;  
      
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState)    {  
        super.onCreate(savedInstanceState);  
        /* 加载display.xml Layout */ 
        setContentView(R.layout.display);  
          
        /* 取得屏幕分辨率大小 */ 
        DisplayMetrics dm=new DisplayMetrics();  
        getWindowManager().getDefaultDisplay().getMetrics(dm);  
        displayWidth=dm.widthPixels;  
        displayHeight=dm.heightPixels;   
          
        /* 初始化相关变量 */ 
        Bundle bundle = this.getIntent().getExtras();  
        Integer imageId = bundle.getInt("imageId");  
        Log.i(TAG, "onCreate, imageId = " + imageId);  
                       
        bmp=BitmapFactory.decodeResource(getResources(), imageId);   
        mImageView = (ImageView)findViewById(R.id.myImageView);  
        mImageView.setImageBitmap(bmp);  
        mImageView.setOnTouchListener(this);  
        mImageView.setLongClickable(true);  
          
        layout1 = (FrameLayout)findViewById(R.id.layout1);  
        layoutImage = (LinearLayout)findViewById(R.id.layoutImage);  
        mButton01 = (Button)findViewById(R.id.myButton1);  
        mButton02 = (Button)findViewById(R.id.myButton2);   
          
        /* 缩小按钮onClickListener */ 
        mButton01.setOnClickListener(new Button.OnClickListener() {  
            @Override 
            public void onClick(View v) {  
                small();   
            }  
        });  
          
        /* 放大按钮onClickListener */ 
        mButton02.setOnClickListener(new Button.OnClickListener() {  
            @Override         
            public void onClick(View v) {  
                big();  
            }   
        });  
    }    
      
    // 用户轻触触摸屏，由1个MotionEvent ACTION_DOWN触发  
    @Override 
    public boolean onDown(MotionEvent e) {  
        // TODO Auto-generated method stub  
//      Toast.makeText(this, "onDown", Toast.LENGTH_SHORT).show();      
        Log.i(TAG, "onDown...");  
          
        return false;  
    }  
 
    /* 用户按下触摸屏、快速移动后松开，由1个MotionEvent ACTION_DOWN,  
     * 多个ACTION_MOVE, 1个ACTION_UP触发 
     * 参数解释：  
     * e1：第1个ACTION_DOWN MotionEvent  
     * e2：最后一个ACTION_MOVE MotionEvent  
     * velocityX：X轴上的移动速度，像素/秒  
     * velocityY：Y轴上的移动速度，像素/秒  
     * 触发条件 ：  
     * X轴的坐标位移大于FLING_MIN_DISTANCE，且移动速度大于FLING_MIN_VELOCITY个像素/秒 
     * @see android.view.GestureDetector$OnGestureListener#onFling(android.view.MotionEvent, android.view.MotionEvent, float, float) 
     */ 
    @Override 
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,  
            float velocityY) {  
        // TODO Auto-generated method stub  
        Log.i(TAG, "onFling...");  
          
        if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE      
                 && Math.abs(velocityX) > FLING_MIN_VELOCITY) {      
            // Fling left   
 
             Toast.makeText(this, "Fling Left", Toast.LENGTH_SHORT).show();      
         } else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE      
                 && Math.abs(velocityX) > FLING_MIN_VELOCITY) {      
 
             // Fling right   
 
             Toast.makeText(this, "Fling Right", Toast.LENGTH_SHORT).show();      
         }    
          
        return false;  
    }  
 
    // 用户长按触摸屏，由多个MotionEvent ACTION_DOWN触发   
    @Override 
    public void onLongPress(MotionEvent e) {  
        // TODO Auto-generated method stub  
        Log.i(TAG, "onLongPress...");  
          
    }  
 
    // 用户按下触摸屏，并拖动，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE触发  
    @Override 
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,  
            float distanceY) {  
        // TODO Auto-generated method stub  
        Log.i(TAG, "onScroll...");  
          
        return false;  
    }  
 
    // 用户轻触触摸屏，尚未松开或拖动，由一个1个MotionEvent ACTION_DOWN触发  
    // 注意和onDown()的区别，强调的是没有松开或者拖动的状态  
    @Override 
    public void onShowPress(MotionEvent e) {  
        // TODO Auto-generated method stub  
        Log.i(TAG, "onShowPress...");  
          
    }  
 
    // 用户（轻触触摸屏后）松开，由一个1个MotionEvent ACTION_UP触发  
    @Override 
    public boolean onSingleTapUp(MotionEvent e) {  
        // TODO Auto-generated method stub  
        Log.i(TAG, "onSingleTapUp...");  
          
        return false;  
    }  
 
    @Override 
    public boolean onTouch(View v, MotionEvent event) {  
        // TODO Auto-generated method stub  
        Log.i(TAG, "onTouch...");  
          
        // Set button visible  
        mButton01.setVisibility(View.VISIBLE);  
        mButton02.setVisibility(View.VISIBLE);  
          
        return  mGestureDetector.onTouchEvent(event);      
    }  
 
//  @Override  
//  public boolean onTouchEvent(MotionEvent event) {  
//      // TODO Auto-generated method stub  
//      super.onTouchEvent(event);  
//        
//      Log.i(TAG, "onTouchEvent");  
//      // Set button visible  
//      mButton01.setVisibility(View.VISIBLE);  
//      mButton02.setVisibility(View.VISIBLE);  
//        
//      return true;  
//  }  
      
    @Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) {  
        // TODO Auto-generated method stub  
        super.onKeyDown(keyCode, event);  
          
        Log.i(TAG, "onKeyDown...");  
        // Set button visible  
        mButton01.setVisibility(View.VISIBLE);  
        mButton02.setVisibility(View.VISIBLE);  
          
        return true;  
    }  
 
    /* 图片缩小的method */ 
    private void small()    {  
        int bmpWidth=bmp.getWidth();   
        int bmpHeight=bmp.getHeight();  
          
        Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);  
          
        /* 设置图片缩小的比例 */ 
        double scale=0.8;  
        /* 计算出这次要缩小的比例 */   
        scaleWidth=(float) (scaleWidth*scale);   
        scaleHeight=(float) (scaleHeight*scale);   
        /* 产生reSize后的Bitmap对象 */ 
        Matrix matrix = new Matrix();  
        matrix.postScale(scaleWidth, scaleHeight);  
        Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth,   
                bmpHeight,matrix,true);   
          
        if(id==0)      {  
            /* 如果是第一次按，就删除原来默认的ImageView */ 
            layoutImage.removeView(mImageView);  
        } else {  
            /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */ 
            layoutImage.removeView((ImageView)findViewById(id));  
        }   
          
        /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */ 
        id++;  
        ImageView imageView = new ImageView(this);  
        imageView.setId(id);  
        imageView.setImageBitmap(resizeBmp);  
        layoutImage.addView(imageView);  
        Log.i(TAG, "imageView.getWidth() = " + imageView.getWidth()  
                + ", imageView.getHeight() = " + imageView.getHeight());  
        setContentView(layout1);  
        /* 因为图片放到最大时放大按钮会disable，所以在缩小时把它重设为enable */   
        mButton02.setEnabled(true);  
        mButton02.setTextColor(Color.MAGENTA);  
    }  
      
    /* 图片放大的method */ 
    private void big() {  
        int bmpWidth=bmp.getWidth();  
        int bmpHeight=bmp.getHeight();  
          
        Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);  
          
        /* 设置图片放大的比例 */ 
        double scale=1.25;  
        /* 计算这次要放大的比例 */ 
        scaleWidth=(float)(scaleWidth*scale);  
        scaleHeight=(float)(scaleHeight*scale);  
        /* 产生reSize后的Bitmap对象 */ 
        Matrix matrix = new Matrix();  
        matrix.postScale(scaleWidth, scaleHeight);  
        Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth,   
                bmpHeight,matrix,true);  
          
        if(id==0) {  
            /* 如果是第一次按，就删除原来设置的ImageView */ 
            layoutImage.removeView(mImageView);  
        } else {  
            /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */   
            layoutImage.removeView((ImageView)findViewById(id));  
        }  
          
        /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */ 
        id++;  
        ImageView imageView = new ImageView(this);  
        imageView.setId(id);  
        imageView.setImageBitmap(resizeBmp);  
        layoutImage.addView(imageView);  
        setContentView(layout1);  
        /* 如果再放大会超过屏幕大小，就把Button disable */ 
        if( scaleWidth * scale * bmpWidth > bmpWidth * 3 ||  
            scaleHeight * scale * bmpHeight > bmpWidth * 3 ||  
            scaleWidth * scale * bmpWidth > displayWidth * 5 ||  
            scaleHeight * scale * bmpHeight > displayHeight * 5) {  
                mButton02.setEnabled(false);  
                mButton02.setTextColor(Color.GRAY);  
            } else {  
                mButton02.setEnabled(true);  
                mButton02.setTextColor(Color.MAGENTA);  
            }  
        }   
      
} 
package com.min.Test_Gallery;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.graphics.Matrix;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.GestureDetector;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.OnGestureListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.Toast;

public class DisplayImage extends Activity implements OnTouchListener, OnGestureListener  {
 private static final String TAG = "DisplayImage";
 private static final int FLING_MIN_DISTANCE = 100;
 private static final int FLING_MIN_VELOCITY = 200;
 
 
 /* 相关变量声明 */
 private ImageView mImageView;
 private Button mButton01;
 private Button mButton02;
 private FrameLayout layout1;
 private LinearLayout layoutImage;
 private Bitmap bmp;
 private int id=0;
 private int displayWidth;
 private int displayHeight;
 private float scaleWidth=1;
 private float scaleHeight=1;
 private GestureDetector mGestureDetector;
 
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState)    {
  super.onCreate(savedInstanceState);
  /* 加载display.xml Layout */
  setContentView(R.layout.display);
  
  /* 取得屏幕分辨率大小 */
  DisplayMetrics dm=new DisplayMetrics();
  getWindowManager().getDefaultDisplay().getMetrics(dm);
  displayWidth=dm.widthPixels;
  displayHeight=dm.heightPixels;
  
  /* 初始化相关变量 */
  Bundle bundle = this.getIntent().getExtras();
  Integer imageId = bundle.getInt("imageId");
  Log.i(TAG, "onCreate, imageId = " + imageId);
                   
  bmp=BitmapFactory.decodeResource(getResources(), imageId);
  mImageView = (ImageView)findViewById(R.id.myImageView);
  mImageView.setImageBitmap(bmp);
  mImageView.setOnTouchListener(this);
  mImageView.setLongClickable(true);
  
  layout1 = (FrameLayout)findViewById(R.id.layout1);
  layoutImage = (LinearLayout)findViewById(R.id.layoutImage);
  mButton01 = (Button)findViewById(R.id.myButton1);
  mButton02 = (Button)findViewById(R.id.myButton2);
  
  /* 缩小按钮onClickListener */
  mButton01.setOnClickListener(new Button.OnClickListener() {
   @Override
   public void onClick(View v) {
    small();
   }
  });
  
  /* 放大按钮onClickListener */
  mButton02.setOnClickListener(new Button.OnClickListener() {
   @Override      
   public void onClick(View v) {
    big();
   }
  });
 } 
 
 // 用户轻触触摸屏，由1个MotionEvent ACTION_DOWN触发
 @Override
 public boolean onDown(MotionEvent e) {
  // TODO Auto-generated method stub
//  Toast.makeText(this, "onDown", Toast.LENGTH_SHORT).show();   
  Log.i(TAG, "onDown...");
  
  return false;
 }

 /* 用户按下触摸屏、快速移动后松开，由1个MotionEvent ACTION_DOWN,
  * 多个ACTION_MOVE, 1个ACTION_UP触发
  * 参数解释：
  * e1：第1个ACTION_DOWN MotionEvent
  * e2：最后一个ACTION_MOVE MotionEvent
  * velocityX：X轴上的移动速度，像素/秒
  * velocityY：Y轴上的移动速度，像素/秒
  * 触发条件 ：
  * X轴的坐标位移大于FLING_MIN_DISTANCE，且移动速度大于FLING_MIN_VELOCITY个像素/秒
  * @see android.view.GestureDetector$OnGestureListener#onFling(android.view.MotionEvent, android.view.MotionEvent, float, float)
  */
 @Override
 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
   float velocityY) {
  // TODO Auto-generated method stub
  Log.i(TAG, "onFling...");
  
  if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE   
              && Math.abs(velocityX) > FLING_MIN_VELOCITY) {   
   // Fling left

          Toast.makeText(this, "Fling Left", Toast.LENGTH_SHORT).show();   
      } else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE   
              && Math.abs(velocityX) > FLING_MIN_VELOCITY) {   

       // Fling right

          Toast.makeText(this, "Fling Right", Toast.LENGTH_SHORT).show();   
      } 
  
  return false;
 }

 // 用户长按触摸屏，由多个MotionEvent ACTION_DOWN触发
 @Override
 public void onLongPress(MotionEvent e) {
  // TODO Auto-generated method stub
  Log.i(TAG, "onLongPress...");
  
 }

 // 用户按下触摸屏，并拖动，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE触发
 @Override
 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
   float distanceY) {
  // TODO Auto-generated method stub
  Log.i(TAG, "onScroll...");
  
  return false;
 }

 // 用户轻触触摸屏，尚未松开或拖动，由一个1个MotionEvent ACTION_DOWN触发
 // 注意和onDown()的区别，强调的是没有松开或者拖动的状态
 @Override
 public void onShowPress(MotionEvent e) {
  // TODO Auto-generated method stub
  Log.i(TAG, "onShowPress...");
  
 }

 // 用户（轻触触摸屏后）松开，由一个1个MotionEvent ACTION_UP触发
 @Override
 public boolean onSingleTapUp(MotionEvent e) {
  // TODO Auto-generated method stub
  Log.i(TAG, "onSingleTapUp...");
  
  return false;
 }

 @Override
 public boolean onTouch(View v, MotionEvent event) {
  // TODO Auto-generated method stub
  Log.i(TAG, "onTouch...");
  
  // Set button visible
  mButton01.setVisibility(View.VISIBLE);
  mButton02.setVisibility(View.VISIBLE);
  
  return  mGestureDetector.onTouchEvent(event);   
 }

// @Override
// public boolean onTouchEvent(MotionEvent event) {
//  // TODO Auto-generated method stub
//  super.onTouchEvent(event);
//  
//  Log.i(TAG, "onTouchEvent");
//  // Set button visible
//  mButton01.setVisibility(View.VISIBLE);
//  mButton02.setVisibility(View.VISIBLE);
//  
//  return true;
// }
 
 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
  // TODO Auto-generated method stub
  super.onKeyDown(keyCode, event);
  
  Log.i(TAG, "onKeyDown...");
  // Set button visible
  mButton01.setVisibility(View.VISIBLE);
  mButton02.setVisibility(View.VISIBLE);
  
  return true;
 }

 /* 图片缩小的method */
 private void small()    {
  int bmpWidth=bmp.getWidth();
  int bmpHeight=bmp.getHeight();
  
  Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);
  
  /* 设置图片缩小的比例 */
  double scale=0.8;
  /* 计算出这次要缩小的比例 */
  scaleWidth=(float) (scaleWidth*scale);
  scaleHeight=(float) (scaleHeight*scale);
  /* 产生reSize后的Bitmap对象 */
  Matrix matrix = new Matrix();
  matrix.postScale(scaleWidth, scaleHeight);
  Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth,
    bmpHeight,matrix,true);
  
  if(id==0)      {
   /* 如果是第一次按，就删除原来默认的ImageView */
   layoutImage.removeView(mImageView);
  } else {
   /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */
   layoutImage.removeView((ImageView)findViewById(id));
  }
  
  /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */
  id++;
  ImageView imageView = new ImageView(this);
  imageView.setId(id);
  imageView.setImageBitmap(resizeBmp);
  layoutImage.addView(imageView);
  Log.i(TAG, "imageView.getWidth() = " + imageView.getWidth()
    + ", imageView.getHeight() = " + imageView.getHeight());
  setContentView(layout1);
  /* 因为图片放到最大时放大按钮会disable，所以在缩小时把它重设为enable */
  mButton02.setEnabled(true);
  mButton02.setTextColor(Color.MAGENTA);
 }
 
 /* 图片放大的method */
 private void big() {
  int bmpWidth=bmp.getWidth();
  int bmpHeight=bmp.getHeight();
  
  Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);
  
  /* 设置图片放大的比例 */
  double scale=1.25;
  /* 计算这次要放大的比例 */
  scaleWidth=(float)(scaleWidth*scale);
  scaleHeight=(float)(scaleHeight*scale);
  /* 产生reSize后的Bitmap对象 */
  Matrix matrix = new Matrix();
  matrix.postScale(scaleWidth, scaleHeight);
  Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth,
    bmpHeight,matrix,true);
  
  if(id==0) {
   /* 如果是第一次按，就删除原来设置的ImageView */
   layoutImage.removeView(mImageView);
  } else {
   /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */
   layoutImage.removeView((ImageView)findViewById(id));
  }
  
  /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */
  id++;
  ImageView imageView = new ImageView(this);
  imageView.setId(id);
  imageView.setImageBitmap(resizeBmp);
  layoutImage.addView(imageView);
  setContentView(layout1);
  /* 如果再放大会超过屏幕大小，就把Button disable */
  if( scaleWidth * scale * bmpWidth > bmpWidth * 3 ||
   scaleHeight * scale * bmpHeight > bmpWidth * 3 ||
   scaleWidth * scale * bmpWidth > displayWidth * 5 ||
   scaleHeight * scale * bmpHeight > displayHeight * 5) {
    mButton02.setEnabled(false);
    mButton02.setTextColor(Color.GRAY);
   } else {
    mButton02.setEnabled(true);
    mButton02.setTextColor(Color.MAGENTA);
   }
  }
 
}

display.xml文件

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<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:id="@+id/layout1" 
    > 
 
    <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"     
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content"   
        android:layout_weight="19" 
        android:scrollbars="vertical" 
        android:fadingEdge="vertical"> 
    <HorizontalScrollView   
        android:layout_height="fill_parent" 
        android:layout_width="wrap_content"> 
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
            android:orientation="horizontal" 
            android:layout_width="fill_parent" 
            android:layout_height="wrap_content" 
            android:gravity="center" 
            android:id="@+id/layoutImage" 
            > 
            <ImageView 
                android:id="@+id/myImageView" 
                android:layout_width="fill_parent" 
                android:layout_height="wrap_content" 
                android:layout_weight="19" 
                android:paddingTop="5dip" 
                android:paddingBottom="5dip" 
                /> 
        </LinearLayout> 
    </HorizontalScrollView > 
    </ScrollView>   
 
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        > 
        <Button 
            android:id="@+id/myButton1" 
            android:layout_width="45dip" 
            android:layout_height="30dip" 
            android:layout_alignParentLeft="true" 
            android:gravity="left" 
            style="@style/my_style_button" 
            android:visibility="gone" 
            android:text="缩小" 
            /> 
        <Button 
            android:id="@+id/myButton2" 
            android:layout_width="45dip" 
            android:layout_height="30dip" 
            android:layout_alignParentRight="true" 
            android:gravity="right" 
            style="@style/my_style_button" 
            android:visibility="gone" 
            android:text="放大" 
            /> 
    </RelativeLayout> 
</FrameLayout>