用OnTouchEvent移動視圖

Question

我有這段代碼可以將視圖放在屏幕上。 但視圖並不完全遵循我手指觸摸的點。

我可以改善這種行爲嗎？

要像拖放API一樣工作，但使用onTouchEvent？

謝謝大家！

@Override 
public boolean onTouchEvent(final MotionEvent event) { 

      final float x = event.getX(); 
      final float y = event.getY(); 
      moveView(x, y); 
      return super.onTouchEvent(event); 

     } 

     private void moveView(float x, float y) { 
      RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT); 
      params.leftMargin = Math.round(x); 
      params.topMargin = Math.round(y); 
      selectedView.setLayoutParams(params); 

     } 

Answer 1

試圖用打轉轉偏移到您的x和y座標。

//should be on the order of magnitude of the size of the view 
float x_offset= 10; //Play with this. 
float y_offset= 10; //Play with this. 

final float x = event.getX() + x_offset; 
final float y = event.getY() + y_offset; 

moveView(x, y); 

Answer 2

嘗試從RelativeLayout的改變你的佈局，以AbsoluteLayout

Answer 3

// These matrices will be used to scale points of the image 
Matrix matrix = new Matrix(); 
Matrix savedMatrix = new Matrix(); 


// The 3 states (events) which the user is trying to perform 
static final int NONE = 0; 
static final int DRAG = 1; 
static final int ZOOM = 2; 
//private static final float MAX_ZOOM = 5f; 
int mode = NONE; 

// these PointF objects are used to record the point(s) the user is touching 
PointF start = new PointF(); 
PointF mid = new PointF(); 
float oldDist = 1f; 
float[] lastEvent = null; 
float degrees = 0f; 
float newRot = 0f; 



OnTouchListener touchAction = new OnTouchListener() { 

    @Override 
    public boolean onTouch(View v, MotionEvent event) { 

     //perfrom zoom & drag & rotate operations on touch of imageview 
     dragZoomRotate((ImageView)v, event); 
     return true; 

    } 
}; 

private void dragZoomRotate(ImageView view, MotionEvent event){ 

    view.setScaleType(ImageView.ScaleType.MATRIX); 

    // Handle touch events here... 

    switch (event.getAction() & MotionEvent.ACTION_MASK) 
    { 
    case MotionEvent.ACTION_DOWN: 
     savedMatrix.set(matrix); 
     start.set(event.getX() , event.getY()); 
     mode = DRAG; 
     lastEvent = null; 
     break; 
    case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down 
     oldDist = spacing(event);   
     savedMatrix.set(matrix); 
     midPoint(mid, event); 
     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); 
     degrees = rotation(event); 
     break; 
    case MotionEvent.ACTION_UP: // first finger lifted 
    case MotionEvent.ACTION_POINTER_UP: // second finger lifted 
     mode = NONE; 
     lastEvent = null; 

     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); 
      matrix.set(savedMatrix); 
      if (newDist > 10f) {    
       float scale = newDist/oldDist; 
       matrix.postScale(scale, scale, mid.x, mid.y); 
      } 
      if (lastEvent!=null){ 
       newRot = rotation(event); 
       float r = newRot-degrees; 
       matrix.postRotate(r, view.getMeasuredWidth()/2, view.getMeasuredHeight()/2); 
      } 
     } 
     // 
     break; 
    } 

    view.setImageMatrix(matrix); 
} 

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); 
    return (float) Math.toDegrees(radians);   
} 




/*  
* -------------------------------------------------------------------------- 
* Method: spacing Parameters: MotionEvent Returns: float Description: 
* 
* checks the spacing between the two fingers on touch 
* ---------------------------------------------------- 
*/ 

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); 
} 

/* 
* -------------------------------------------------------------------------- 
* Method: midPoint Parameters: PointF object, MotionEvent Returns: void 
* Description: calculates the midpoint between the two fingers 
* ------------------------------------------------------------ 
*/ 

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); 
} 

現在添加touchAction監聽器要移動視圖...

myImageView.setOnTouchListener(touchAction);