android 大圖片拖拽縮放

      這篇圖片拖拽縮放也是我在項目中用到的，今天整理一下，將源碼奉獻給大家，希望對大家以后碰到相似的問題有幫助。

     

           這篇就不做過多介紹了，直接上源碼：

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);//隱藏標題  
        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);

        //加載成功
        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;   
        } 
    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();   //回收圖片所占的內存
                bitmap=null;
                 System.gc();  //提醒系統及時回收
         }
        }
    super.onStop();
}
    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        if(bitmap!=null){
        if(!bitmap.isRecycled()){
            bitmap.recycle();   //回收圖片所占的內存
            bitmap=null;
             System.gc();  //提醒系統及時回收
     }
        }
    }
}

     因為是大圖片，在onDestroy的時候要recycle掉，這樣系統才會定時回收掉，System.gc();是提醒系統回收，雖然java這種垃圾 回收機制不用我們自己關心對象的回收，但是這也給android開發人員帶來了不好的一面，如果系統回收不及時很可能就造成了內存溢出了。什么時候手機不 擔心內存使用了就好了。

   運行一下看看效果：

 

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