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：

 public class SpacePageActivity extends Activity {  

     private LinearLayout linnerLayout_spacepage;
     private RelativeLayout relativeLayout_spacepage;
     private Button btn_spacepage_back;
     private Button btn_spacepage_save;
     private static Boolean isTrue=false;  

     private static  String IMAGE_MIME_TYPE ;  

     private ImageView image_spacePage;
     private ProgressDialog dialog;
     private Bitmap bitmap;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);
         requestWindowFeature(Window.FEATURE_NO_TITLE);//隐藏标题
         setContentView(R.layout.spacepage);
         setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
         initHead();  

         if(isNetworkAvailable()){
         image_spacePage=(ImageView) findViewById(R.id.image_spacepage);
         btn_spacepage_save=(Button) findViewById(R.id.btn_spacepage_save);
         image_spacePage.setOnTouchListener(new MulitPointTouchListener(image_spacePage));
         image_spacePage.setScaleType(ScaleType.CENTER_INSIDE);  

         //加载成功   何问起
         String urls="http://epaper.yzdsb.com.cn/201201/04/yz2104_7.jpg";
         bitmap=returnBitMap(urls);
         if(null!=bitmap){
          image_spacePage.setImageBitmap(bitmap);
         }  

         }
     }   

     public Bitmap returnBitMap(String url) {    

          if(null==url || "".equals(url)){
              return null;
          }
            URL myFileUrl = null;
            Bitmap bitmap = null;
            try {
             myFileUrl = new URL(url);
            } catch (MalformedURLException e) {
             e.printStackTrace();
            }
            try {
             HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();
             conn.setConnectTimeout(2000);
             conn.setDoInput(true);
             conn.connect();
             InputStream is = conn.getInputStream();
             bitmap = BitmapFactory.decodeStream(is);
             is.close();
            } catch (IOException e) {
             e.printStackTrace();
            }     

            return bitmap;
         }
 // hovertree.com

     public class MulitPointTouchListener implements OnTouchListener {      

         Matrix matrix = new Matrix();
         Matrix savedMatrix = new Matrix();      

         public ImageView image;
         static final int NONE = 0;
         static final int DRAG = 1;
         static final int ZOOM = 2;
         int mode = NONE;      

         PointF start = new PointF();
         PointF mid = new PointF();
         float oldDist = 1f;      

         public MulitPointTouchListener(ImageView image) {
             super();
             this.image = image;
         }      

         @Override
         public boolean onTouch(View v, MotionEvent event) {
             this.image.setScaleType(ScaleType.MATRIX);      

             ImageView view = (ImageView) v;
 //        dumpEvent(event);      

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

             case MotionEvent.ACTION_DOWN:      

                 Log.w("FLAG", "ACTION_DOWN");
                 matrix.set(view.getImageMatrix());
                 savedMatrix.set(matrix);
                 start.set(event.getX(), event.getY());
                 mode = DRAG;
                 break;
             case MotionEvent.ACTION_POINTER_DOWN:
                 Log.w("FLAG", "ACTION_POINTER_DOWN");
                 oldDist = spacing(event);
                 if (oldDist > 10f) {
                     savedMatrix.set(matrix);
                     midPoint(mid, event);
                     mode = ZOOM;
                 }
                 break;
             case MotionEvent.ACTION_UP:
                 Log.w("FLAG", "ACTION_UP");
             case MotionEvent.ACTION_POINTER_UP:
                 Log.w("FLAG", "ACTION_POINTER_UP");
                 mode = NONE;
                 break;
             case MotionEvent.ACTION_MOVE:
                 Log.w("FLAG", "ACTION_MOVE");
                 if (mode == DRAG) {
                     matrix.set(savedMatrix);
                     matrix.postTranslate(event.getX() - start.x, event.getY()
                             - start.y);
                 } else if (mode == ZOOM) {
                     float newDist = spacing(event);
                     if (newDist > 10f) {
                         matrix.set(savedMatrix);
                         float scale = newDist / oldDist;
                         matrix.postScale(scale, scale, mid.x, mid.y);
                     }
                 }
                 break;
             }      

             view.setImageMatrix(matrix);
             return true;
         }      

         private float spacing(MotionEvent event) {
             float x = event.getX(0) - event.getX(1);
             float y = event.getY(0) - event.getY(1);
             return FloatMath.sqrt(x * x + y * y);
         }      

         private void midPoint(PointF point, MotionEvent event) {
             float x = event.getX(0) + event.getX(1);
             float y = event.getY(0) + event.getY(1);
             point.set(x / 2, y / 2);
         }
     }
     private void initHead() {
         linnerLayout_spacepage = (LinearLayout) findViewById(R.id.linnerLayout_spacepage);
         relativeLayout_spacepage=(RelativeLayout) findViewById(R.id.relativeLayout_spacepage);
         btn_spacepage_back = (Button) findViewById(R.id.btn_spacepage_back);
         btn_spacepage_back.setOnClickListener(new OnClickListener() {  

             @Override
             public void onClick(View v) {
                 // TODO Auto-generated method stub  

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

     }
     protected boolean isNetworkAvailable() {
         ConnectivityManager connectivity = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
         if (connectivity == null) {
             Log.i("NetWorkState", "Unavailabel");
             return false;
         } else {
             NetworkInfo[] info = connectivity.getAllNetworkInfo();
             if (info != null) {
                 for (int i = 0; i < info.length; i++) {
                     if (info[i].getState() == NetworkInfo.State.CONNECTED) {
                         Log.i("NetWorkState", "Availabel");
                         return true;
                     }
                 }
             }
         }
         return false;
     }
    @Override
 protected void onStop() {
     // TODO Auto-generated method stub
        if(bitmap!=null){
             if(!bitmap.isRecycled()){
                 bitmap.recycle();   //回收图片所占的内存
                 bitmap=null;
                  System.gc();  //提醒系统及时回收
          }
         }
     super.onStop();
 }
     @Override
     protected void onDestroy() {
         // TODO Auto-generated method stub
         super.onDestroy();
         if(bitmap!=null){
         if(!bitmap.isRecycled()){
             bitmap.recycle();   //回收图片所占的内存
             bitmap=null;
              System.gc();  //提醒系统及时回收
      }
         }
     }
 }  

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：