android 大图片拖拽缩放

这篇图片拖拽缩放也是我在项目中用到的，今天整理一下，将源码奉献给大家，希望对大家以后碰到相似的问题有帮助。
这篇就不做过多介绍了，直接上源码：
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public class SpacePageActivity extends Activity { 

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    private LinearLayout linnerLayout_spacepage; 

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    private RelativeLayout relativeLayout_spacepage; 

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    private Button btn_spacepage_back; 

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    private Button btn_spacepage_save; 

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    private static Boolean isTrue=false; 

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    private static  String IMAGE_MIME_TYPE ; 

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    private ImageView image_spacePage; 

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    private ProgressDialog dialog; 

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    private Bitmap bitmap; 

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    @Override

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    protected void onCreate(Bundle savedInstanceState) { 

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        // TODO Auto-generated method stub 

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        super.onCreate(savedInstanceState); 

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        requestWindowFeature(Window.FEATURE_NO_TITLE);//隐藏标题   

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        setContentView(R.layout.spacepage); 

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        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);    

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        initHead(); 

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        if(isNetworkAvailable()){ 

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        image_spacePage=(ImageView) findViewById(R.id.image_spacepage); 

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        btn_spacepage_save=(Button) findViewById(R.id.btn_spacepage_save); 

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        image_spacePage.setOnTouchListener(new MulitPointTouchListener(image_spacePage)); 

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        image_spacePage.setScaleType(ScaleType.CENTER_INSIDE); 

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        //加载成功 

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        String urls="http://epaper.yzdsb.com.cn/201201/04/yz2104_7.jpg"; 

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        bitmap=returnBitMap(urls); 

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        if(null!=bitmap){ 

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         image_spacePage.setImageBitmap(bitmap); 

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        } 

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        } 

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    }  

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    public Bitmap returnBitMap(String url) {   

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         if(null==url || "".equals(url)){ 

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             return null; 

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         } 

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           URL myFileUrl = null;    

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           Bitmap bitmap = null;    

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           try {    

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            myFileUrl = new URL(url);    

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           } catch (MalformedURLException e) {    

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            e.printStackTrace();    

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           }    

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           try {    

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            HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection(); 

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            conn.setConnectTimeout(2000); 

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            conn.setDoInput(true);    

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            conn.connect();    

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            InputStream is = conn.getInputStream();    

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            bitmap = BitmapFactory.decodeStream(is);    

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            is.close();    

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           } catch (IOException e) {    

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            e.printStackTrace();    

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           }    

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           return bitmap;    

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        }  

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    public class MulitPointTouchListener implements OnTouchListener {     

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        Matrix matrix = new Matrix();     

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        Matrix savedMatrix = new Matrix();     

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        public ImageView image;     

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        static final int NONE = 0;     

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        static final int DRAG = 1;     

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        static final int ZOOM = 2;     

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        int mode = NONE;     

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        PointF start = new PointF();     

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        PointF mid = new PointF();     

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        float oldDist = 1f;     

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        public MulitPointTouchListener(ImageView image) {     

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            super();     

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            this.image = image;     

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        }     

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        @Override    

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        public boolean onTouch(View v, MotionEvent event) {     

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            this.image.setScaleType(ScaleType.MATRIX);     

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            ImageView view = (ImageView) v;     

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//        dumpEvent(event);     

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            switch (event.getAction() & MotionEvent.ACTION_MASK) {   

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            case MotionEvent.ACTION_DOWN:     

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                Log.w("FLAG", "ACTION_DOWN");   

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                matrix.set(view.getImageMatrix());     

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                savedMatrix.set(matrix);     

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                start.set(event.getX(), event.getY());     

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                mode = DRAG;     

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                break;     

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            case MotionEvent.ACTION_POINTER_DOWN:     

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                Log.w("FLAG", "ACTION_POINTER_DOWN");   

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                oldDist = spacing(event);     

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                if (oldDist > 10f) {     

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                    savedMatrix.set(matrix);     

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                    midPoint(mid, event);     

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                    mode = ZOOM;     

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                }     

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                break;     

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            case MotionEvent.ACTION_UP:     

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                Log.w("FLAG", "ACTION_UP");   

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            case MotionEvent.ACTION_POINTER_UP:     

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                Log.w("FLAG", "ACTION_POINTER_UP");   

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                mode = NONE;     

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                break;     

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            case MotionEvent.ACTION_MOVE:     

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                Log.w("FLAG", "ACTION_MOVE");   

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                if (mode == DRAG) {     

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                    matrix.set(savedMatrix);     

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                    matrix.postTranslate(event.getX() - start.x, event.getY()     

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                            - start.y);     

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                } else if (mode == ZOOM) {     

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                    float newDist = spacing(event);     

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                    if (newDist > 10f) {     

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                        matrix.set(savedMatrix);     

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                        float scale = newDist / oldDist;     

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                        matrix.postScale(scale, scale, mid.x, mid.y);     

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                    }     

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                }     

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                break;     

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            }     

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            view.setImageMatrix(matrix);     

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            return true;   

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        }     

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        private float spacing(MotionEvent event) {     

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            float x = event.getX(0) - event.getX(1);     

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            float y = event.getY(0) - event.getY(1);     

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            return FloatMath.sqrt(x * x + y * y);     

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        }     

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        private void midPoint(PointF point, MotionEvent event) {     

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            float x = event.getX(0) + event.getX(1);     

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            float y = event.getY(0) + event.getY(1);     

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            point.set(x / 2, y / 2);     

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        }     

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    }    

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    private void initHead() { 

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        linnerLayout_spacepage = (LinearLayout) findViewById(R.id.linnerLayout_spacepage); 

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        relativeLayout_spacepage=(RelativeLayout) findViewById(R.id.relativeLayout_spacepage); 

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        btn_spacepage_back = (Button) findViewById(R.id.btn_spacepage_back); 

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        btn_spacepage_back.setOnClickListener(new OnClickListener() { 

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            @Override

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            public void onClick(View v) { 

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                // TODO Auto-generated method stub 

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                finish(); 

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            } 

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        }); 

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        btn_spacepage_save = (Button) findViewById(R.id.btn_spacepage_save); 

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    } 

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    protected boolean isNetworkAvailable() { 

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        ConnectivityManager connectivity = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE); 

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        if (connectivity == null) { 

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            Log.i("NetWorkState", "Unavailabel"); 

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            return false; 

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        } else { 

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            NetworkInfo[] info = connectivity.getAllNetworkInfo(); 

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            if (info != null) { 

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                for (int i = 0; i < info.length; i++) { 

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                    if (info[i].getState() == NetworkInfo.State.CONNECTED) { 

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                        Log.i("NetWorkState", "Availabel"); 

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                        return true; 

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                    } 

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                } 

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            } 

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        } 

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        return false; 

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    } 

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   @Override

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protected void onStop() { 

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    // TODO Auto-generated method stub 

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       if(bitmap!=null){ 

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            if(!bitmap.isRecycled()){ 

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                bitmap.recycle();   //回收图片所占的内存 

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                bitmap=null; 

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                 System.gc();  //提醒系统及时回收 

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         } 

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        } 

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    super.onStop(); 

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} 

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    @Override

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    protected void onDestroy() { 

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        // TODO Auto-generated method stub 

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        super.onDestroy(); 

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        if(bitmap!=null){ 

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        if(!bitmap.isRecycled()){ 

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            bitmap.recycle();   //回收图片所占的内存 

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            bitmap=null; 

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             System.gc();  //提醒系统及时回收 

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     } 

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        } 

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    } 

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}
因为是大图片，在onDestroy的时候要recycle掉，这样系统才会定时回收掉，System.gc();是提醒系统回收，虽然java这种垃圾回收机制不用我们自己关心对象的回收，但是这也给android开发人员带来了不好的一面，如果系统回收不及时很可能就造成了内存溢出了。什么时候手机不担心内存使用了就好了。
运行一下看看效果：
android 大图片拖拽缩放
android 大图片拖拽缩放

转自：http://blog.csdn.net/wangkuifeng0118/article/details/7648692