Android 无法收缩和放大图像

我试图在我的代码中实现收缩和缩放功能，但我遇到了一些错误

我在onCreate中添加了一个onTouchListener方法

@Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);

            displayImage();
            viewPager = (ViewPager) findViewById(R.id.view_pager);
            viewPager.setAdapter(new MyAdapter(getSupportFragmentManager()));
            viewPager.setOnPageChangeListener(this);
            viewPager.setOnTouchListener(this);

            //gallery = (Gallery) findViewById(R.id.gallery);
            //gallery.setAdapter(new ImageAdapter());
            //gallery.setOnItemSelectedListener(this);

            //textView = (TextView) findViewById(R.id.title);

            handler = new Handler();

        }

然后这是我的onTouch方法在线检索frm

@Override
public boolean onTouch(View v, MotionEvent event) {
    ImageView imageView = new ImageView(Main.this);
    imageView = (ImageView) v;
    imageView.setScaleType(ImageView.ScaleType.MATRIX);
       float scale;

       // Dump touch event to log
       dumpEvent(event);

       // Handle touch events here...
       switch (event.getAction() & MotionEvent.ACTION_MASK) {

       case MotionEvent.ACTION_DOWN: //first finger down only
          savedMatrix.set(matrix);
          start.set(event.getX(), event.getY());
          Log.d(TAG, "mode=DRAG" );
          mode = DRAG;
          Log.i("saran","mode === drag");
          break;
       case MotionEvent.ACTION_UP: //first finger lifted
           Log.i("saran","action up");
       case MotionEvent.ACTION_POINTER_UP: //second finger lifted
          mode = NONE;
          Log.i("saran", "mode=NONE" );
          break;
       case MotionEvent.ACTION_POINTER_DOWN: //second finger down
          oldDist = spacing(event);
          Log.i("saran", "oldDist=" + oldDist);
          if (oldDist > 5f) {
             savedMatrix.set(matrix);
             midPoint(mid, event);
             mode = ZOOM;
             Log.i("saran", "mode=ZOOM" );
          }
          break;

       case MotionEvent.ACTION_MOVE: 
          /*if (mode == DRAG) { //movement of first finger
             matrix.set(savedMatrix);
             if (view.getLeft() >= -392){
                matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);
             }
             Log.i("saran", "action move.....");
          }
          else*/ if (mode == ZOOM) { //pinch zooming
             float newDist = spacing(event);
             Log.d(TAG, "newDist=" + newDist);
             if (newDist > 5f) {
                matrix.set(savedMatrix);
                scale = newDist / oldDist; //**//thinking i need to play around with this value to limit it**
                matrix.postScale(scale, scale, mid.x, mid.y);
             }
             Log.i("saran", "zoom.......");
          }
          break;
       }

       // Perform the transformation
       imageView.setImageMatrix(matrix);

       return true; // indicate event was handled
    }

    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);
    }

    /** Show an event in the LogCat view, for debugging */
    private void dumpEvent(MotionEvent event) {
       String names[] = { "DOWN" , "UP" , "MOVE" , "CANCEL" , "OUTSIDE" ,
          "POINTER_DOWN" , "POINTER_UP" , "7?" , "8?" , "9?" };
       StringBuilder sb = new StringBuilder();
       int action = event.getAction();
       int actionCode = action & MotionEvent.ACTION_MASK;
       sb.append("event ACTION_" ).append(names[actionCode]);
       if (actionCode == MotionEvent.ACTION_POINTER_DOWN
             || actionCode == MotionEvent.ACTION_POINTER_UP) {
          sb.append("(pid " ).append(
          action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
          sb.append(")" );
       }
       sb.append("[" );
       for (int i = 0; i < event.getPointerCount(); i++) {
          sb.append("#" ).append(i);
          sb.append("(pid " ).append(event.getPointerId(i));
          sb.append(")=" ).append((int) event.getX(i));
          sb.append("," ).append((int) event.getY(i));
          if (i + 1 < event.getPointerCount())
             sb.append(";" );
       }
       sb.append("]" );
       Log.d(TAG, sb.toString());

}

出了什么问题？我尝试使用imageview作为getView中的设置，但它不起作用。请指出我的错误和帮助将不胜感激！多谢各位

viewPager.setOnTouchListener(this);

设置ViewPager的侦听器，但在侦听器中，您可以通过将视图强制转换为ImageView

---

您应该将侦听器附加到ImageView

确保用于初始化ViewPager的ID引用的是XML布局文件中的ViewPager，而不是ImageView。android.support.v4.view.ViewPager无法强制转换为android.widget.ImageViewMy ImageView显示在ImageAdapter上，那么这是否意味着我在那里设置了TouchListener？是的，在ImageAdapter的getView方法中设置它是一种方法。您可能希望将onTouch方法移动到与Activity不同的类。我应该这样做吗？ImageView ImageView=新建ImageViewMain.this；imageView.setOnTouchListenerthis；不，你的onTouch很好，问题是打电话给setOnTouchListner。应该在ImageView的实例上调用它抱歉，我迷路了。你能再说一遍吗？很抱歉

viewPager.setOnTouchListener(this);

imageView = (ImageView) v;