android图片拖动缩放

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。android 大图片拖拽缩放
这篇就不做过多介绍了，直接上源码：
  1 public class SpacePageActivity extends Activity {  
  2   
  3     private LinearLayout linnerLayout_spacepage;  
  4     private RelativeLayout relativeLayout_spacepage;  
  5     private Button btn_spacepage_back;  
  6     private Button btn_spacepage_save;  
  7     private static Boolean isTrue=false;  
  8       
  9     private static  String IMAGE_MIME_TYPE ;  
 10   
 11     private ImageView image_spacePage;  
 12     private ProgressDialog dialog;  
 13     private Bitmap bitmap;  
 14     @Override  
 15     protected void onCreate(Bundle savedInstanceState) {  
 16         // TODO Auto-generated method stub  
 17         super.onCreate(savedInstanceState);  
 18         requestWindowFeature(Window.FEATURE_NO_TITLE);//隐藏标题    
 19         setContentView(R.layout.spacepage);  
 20         setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);     
 21         initHead();  
 22       
 23         if(isNetworkAvailable()){  
 24         image_spacePage=(ImageView) findViewById(R.id.image_spacepage);  
 25         btn_spacepage_save=(Button) findViewById(R.id.btn_spacepage_save);  
 26         image_spacePage.setOnTouchListener(new MulitPointTouchListener(image_spacePage));  
 27         image_spacePage.setScaleType(ScaleType.CENTER_INSIDE);  
 28           
 29         //加载成功   何问起
 30         String urls="http://epaper.yzdsb.com.cn/201201/04/yz2104_7.jpg";  
 31         bitmap=returnBitMap(urls);  
 32         if(null!=bitmap){  
 33          image_spacePage.setImageBitmap(bitmap);  
 34         }  
 35           
 36         }  
 37     }   
 38       
 39   
 40     public Bitmap returnBitMap(String url) {    
 41           
 42          if(null==url || "".equals(url)){  
 43              return null;  
 44          }  
 45            URL myFileUrl = null;     
 46            Bitmap bitmap = null;     
 47            try {     
 48             myFileUrl = new URL(url);     
 49            } catch (MalformedURLException e) {     
 50             e.printStackTrace();     
 51            }     
 52            try {     
 53             HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();  
 54             conn.setConnectTimeout(2000);  
 55             conn.setDoInput(true);     
 56             conn.connect();     
 57             InputStream is = conn.getInputStream();     
 58             bitmap = BitmapFactory.decodeStream(is);     
 59             is.close();     
 60            } catch (IOException e) {     
 61             e.printStackTrace();     
 62            }     
 63              
 64              
 65              
 66            return bitmap;     
 67         }  
 68 // hovertree.com
 69  
 70     public class MulitPointTouchListener implements OnTouchListener {      
 71             
 72         Matrix matrix = new Matrix();      
 73         Matrix savedMatrix = new Matrix();      
 74         
 75         public ImageView image;      
 76         static final int NONE = 0;      
 77         static final int DRAG = 1;      
 78         static final int ZOOM = 2;      
 79         int mode = NONE;      
 80         
 81         PointF start = new PointF();      
 82         PointF mid = new PointF();      
 83         float oldDist = 1f;      
 84         
 85         
 86         public MulitPointTouchListener(ImageView image) {      
 87             super();      
 88             this.image = image;      
 89         }      
 90         
 91         @Override      
 92         public boolean onTouch(View v, MotionEvent event) {      
 93             this.image.setScaleType(ScaleType.MATRIX);      
 94         
 95             ImageView view = (ImageView) v;      
 96 //        dumpEvent(event);      
 97         
 98             switch (event.getAction() & MotionEvent.ACTION_MASK) {    
 99                 
100             case MotionEvent.ACTION_DOWN:      
101         
102                 Log.w("FLAG", "ACTION_DOWN");    
103                 matrix.set(view.getImageMatrix());      
104                 savedMatrix.set(matrix);      
105                 start.set(event.getX(), event.getY());      
106                 mode = DRAG;      
107                 break;      
108             case MotionEvent.ACTION_POINTER_DOWN:      
109                 Log.w("FLAG", "ACTION_POINTER_DOWN");    
110                 oldDist = spacing(event);      
111                 if (oldDist > 10f) {      
112                     savedMatrix.set(matrix);      
113                     midPoint(mid, event);      
114                     mode = ZOOM;      
115                 }      
116                 break;      
117             case MotionEvent.ACTION_UP:      
118                 Log.w("FLAG", "ACTION_UP");    
119             case MotionEvent.ACTION_POINTER_UP:      
120                 Log.w("FLAG", "ACTION_POINTER_UP");    
121                 mode = NONE;      
122                 break;      
123             case MotionEvent.ACTION_MOVE:      
124                 Log.w("FLAG", "ACTION_MOVE");    
125                 if (mode == DRAG) {      
126                     matrix.set(savedMatrix);      
127                     matrix.postTranslate(event.getX() - start.x, event.getY()      
128                             - start.y);      
129                 } else if (mode == ZOOM) {      
130                     float newDist = spacing(event);      
131                     if (newDist > 10f) {      
132                         matrix.set(savedMatrix);      
133                         float scale = newDist / oldDist;      
134                         matrix.postScale(scale, scale, mid.x, mid.y);      
135                     }      
136                 }      
137                 break;      
138             }      
139         
140             view.setImageMatrix(matrix);      
141             return true;    
142         }      
143         
144             
145         private float spacing(MotionEvent event) {      
146             float x = event.getX(0) - event.getX(1);      
147             float y = event.getY(0) - event.getY(1);      
148             return FloatMath.sqrt(x * x + y * y);      
149         }      
150         
151         private void midPoint(PointF point, MotionEvent event) {      
152             float x = event.getX(0) + event.getX(1);      
153             float y = event.getY(0) + event.getY(1);      
154             point.set(x / 2, y / 2);      
155         }      
156     }     
157     private void initHead() {  
158         linnerLayout_spacepage = (LinearLayout) findViewById(R.id.linnerLayout_spacepage);  
159         relativeLayout_spacepage=(RelativeLayout) findViewById(R.id.relativeLayout_spacepage);  
160         btn_spacepage_back = (Button) findViewById(R.id.btn_spacepage_back);  
161         btn_spacepage_back.setOnClickListener(new OnClickListener() {  
162               
163             @Override  
164             public void onClick(View v) {  
165                 // TODO Auto-generated method stub  
166                   
167                 finish();  
168             }  
169         });  
170         btn_spacepage_save = (Button) findViewById(R.id.btn_spacepage_save);  
171           
172     }  
173     protected boolean isNetworkAvailable() {  
174         ConnectivityManager connectivity = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);  
175         if (connectivity == null) {  
176             Log.i("NetWorkState", "Unavailabel");  
177             return false;  
178         } else {  
179             NetworkInfo[] info = connectivity.getAllNetworkInfo();  
180             if (info != null) {  
181                 for (int i = 0; i < info.length; i++) {  
182                     if (info[i].getState() == NetworkInfo.State.CONNECTED) {  
183                         Log.i("NetWorkState", "Availabel");  
184                         return true;  
185                     }  
186                 }  
187             }  
188         }  
189         return false;  
190     }  
191    @Override  
192 protected void onStop() {  
193     // TODO Auto-generated method stub  
194        if(bitmap!=null){  
195             if(!bitmap.isRecycled()){  
196                 bitmap.recycle();   //回收图片所占的内存  
197                 bitmap=null;  
198                  System.gc();  //提醒系统及时回收  
199          }  
200         }  
201     super.onStop();  
202 }  
203     @Override  
204     protected void onDestroy() {  
205         // TODO Auto-generated method stub  
206         super.onDestroy();  
207         if(bitmap!=null){  
208         if(!bitmap.isRecycled()){  
209             bitmap.recycle();   //回收图片所占的内存  
210             bitmap=null;  
211              System.gc();  //提醒系统及时回收  
212      }  
213         }  
214     }  
215 }
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：