android 大圖片拖拽縮放

           由於最近項目忙，部落格一直沒有時間更新，今天有點時間就連續更新兩篇吧，過過癮。

           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，希望對大家以後碰到相似的問題有協助。

     

           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;@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.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);//載入成功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() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubfinish();}});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;}   @Overrideprotected void onStop() {// TODO Auto-generated method stub   if(bitmap!=null){if(!bitmap.isRecycled()){bitmap.recycle();   //回收圖片所佔的記憶體bitmap=null;         System.gc();  //提醒系統及時回收 }}super.onStop();}@Overrideprotected void onDestroy() {// TODO Auto-generated method stubsuper.onDestroy();if(bitmap!=null){if(!bitmap.isRecycled()){bitmap.recycle();   //回收圖片所佔的記憶體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這種記憶體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記憶體溢出了。什麼時候手機不擔心記憶體使用量了就好了。

   運行一下看看效果：