我想在多点触摸事件中旋转和缩放图像， 我可以拖动、缩放图像，但我无法理解图像的旋转。 我遇到了问题所以请尽快帮助我。 我的代码在那里

    public class Touch extends Activity implements OnTouchListener {
       private static final String TAG = "Touch";
      // These matrices will be used to move and zoom image
       Matrix matrix = new Matrix();
   Matrix matrix1 = new Matrix();
   Matrix savedMatrix = new Matrix();
   Matrix savedMatrix2 = new Matrix();
   // We can be in one of these 3 states
   static final int NONE = 0;
   static final int DRAG = 1;
   static final int ZOOM = 2;
   int mode = NONE;
   float oldscale =0;
   // Remember some things for zooming
   PointF start = new PointF();
   PointF mid = new PointF();
   float oldDist = 1f;

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      ImageView view = (ImageView) findViewById(R.id.imageView2);
      view.setOnTouchListener(this);

      ImageView view1 = (ImageView) findViewById(R.id.imageView2);
      view1.setOnTouchListener(this);

      // ...
      // Work around a Cupcake bug
      matrix.setTranslate(1f, 1f);
      matrix1.setTranslate(1f, 1f);
      view.setImageMatrix(matrix);
      view1.setImageMatrix(matrix1);
   }

   @Override
   public boolean onTouch(View v, MotionEvent rawEvent) {
      WrapMotionEvent event = WrapMotionEvent.wrap(rawEvent);
      // ...
      ImageView view = (ImageView) v;

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

      // Handle touch events here...
       double r = Math.atan2(event.getX() - 400 / 2,
            400 / 2 - event.getY());
       int rotation = (int) Math.toDegrees(r);
       float newRot = new Float(rotation);

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

      case MotionEvent.ACTION_DOWN:
         savedMatrix.set(matrix);
         start.set(event.getX(), event.getY());
         Log.d(TAG, "mode=DRAG");
         mode = DRAG;
         break;
       case MotionEvent.ACTION_POINTER_DOWN:
         oldDist = spacing(event);
         Log.d(TAG, "oldDist=" + oldDist);
         if (oldDist > 10f) {
            savedMatrix.set(matrix);
            midPoint(mid, event);
            mode = ZOOM;
            Log.d(TAG, "mode=ZOOM");

         }
         break;
      case MotionEvent.ACTION_UP:
      case MotionEvent.ACTION_POINTER_UP:
         mode = NONE;
         Log.d(TAG, "mode=NONE");
         break;
      case MotionEvent.ACTION_MOVE:
          matrix.postRotate(15);
         if (mode == DRAG) {
            // ...
            matrix.set(savedMatrix);
            matrix.postTranslate(event.getX() - start.x,
                  event.getY() - start.y);
         }
         else if (mode == ZOOM) {
            float newDist = spacing(event);
            Log.d(TAG, "newDist=" + newDist);
            if (newDist > 10f) {
               matrix.set(savedMatrix);
               float scale = newDist / oldDist;
               matrix.postScale(scale, scale, mid.x, mid.y);
               Log.e("scale | mid.x | mid.y", scale + " " +mid.x + " " + mid.y);

            }
         }
         break;
      }
      view.setImageMatrix(matrix);
      return true; // indicate event was handled
   }

   /** Show an event in the LogCat view, for debugging */
   private void dumpEvent(WrapMotionEvent 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());
   }

   /** Determine the space between the first two fingers */
   private float spacing(WrapMotionEvent event) {
      // ...
      float x = event.getX(0) - event.getX(1);
      float y = event.getY(0) - event.getY(1);
      return FloatMath.sqrt(x * x + y * y);
   }

   /** Calculate the mid point of the first two fingers */
   private void midPoint(PointF point, WrapMotionEvent event) {
      // ...
      float x = event.getX(0) + event.getX(1);
      float y = event.getY(0) + event.getY(1);
      point.set(x / 2, y / 2);
   }
}

所以请为我提供这个问题的确切解决方案。

最佳答案

   float[] lastEvent = null;
   float d = 0f;
   float newRot = 0f;
   @Override
   public boolean onTouch(View v, MotionEvent event) {
      ImageView view = (ImageView) v;

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

      // Handle touch events here...
      switch (event.getAction() & MotionEvent.ACTION_MASK) {
      case MotionEvent.ACTION_DOWN:
         savedMatrix.set(matrix);
     start.set(event.getX(), event.getY());
     if (Constant.TRACE) Log.d(TAG, "mode=DRAG");
     mode = DRAG;
     lastEvent = null;
     break;
  case MotionEvent.ACTION_POINTER_DOWN:
     oldDist = spacing(event);         
     savedMatrix.set(matrix);
     midPoint(mid, event);
     mode = ZOOM;
     if (Constant.TRACE) Log.d(TAG, "mode=ZOOM");

     lastEvent = new float[4];
     lastEvent[0] = event.getX(0);
     lastEvent[1] = event.getX(1);
     lastEvent[2] = event.getY(0);
     lastEvent[3] = event.getY(1);
     d = rotation(event);
     break;
  case MotionEvent.ACTION_UP:
  case MotionEvent.ACTION_POINTER_UP:
     mode = NONE;
     lastEvent = null;
     if (Constant.TRACE) Log.d(TAG, "mode=NONE");         
     break;
  case MotionEvent.ACTION_MOVE:
     if (mode == DRAG) {
        // ...
        matrix.set(savedMatrix);
        matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);
     }
     else if (mode == ZOOM && event.getPointerCount()==2) {
        float newDist = spacing(event);
        if (Constant.TRACE) Log.d(TAG, "Count=" + event.getPointerCount());
        if (Constant.TRACE) Log.d(TAG, "newDist=" + newDist);
        matrix.set(savedMatrix);
        if (newDist > 10f) {              
           float scale = newDist / oldDist;
           matrix.postScale(scale, scale, mid.x, mid.y);
        } 
        if (lastEvent!=null){
            newRot = rotation(event); 
            if (Constant.TRACE) Log.d("Degreeeeeeeeeee", "newRot="+(newRot));
            float r = newRot-d;
            matrix.postRotate(r, imgView.getMeasuredWidth()/2, imgView.getMeasuredHeight()/2);  
        }
     }
     break;
  }

  view.setImageMatrix(matrix);
  return true; // indicate event was handled

/** Determine the degree between the first two fingers */
   private float rotation(MotionEvent event) {  
       double delta_x = (event.getX(0) - event.getX(1));
       double delta_y = (event.getY(0) - event.getY(1));
       double radians = Math.atan2(delta_y, delta_x);       
       if (Constant.TRACE) Log.d("Rotation ~~~~~~~~~~~~~~~~~", delta_x+" ## "+delta_y+" ## "+radians+" ## "
                        +Math.toDegrees(radians));
       return (float) Math.toDegrees(radians);
   }

试试这个代码，但记住一些旧手机有旋转问题..

关于android - 在android中使用多点触控进行旋转和缩放，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8515709/