MotionEvent在視圖上同時移動兩個位圖

Question

我在視圖中使用以下類（Android中的簡單2D圖形）創建了兩個位圖並漫遊以實現該位圖可以獨立移動。我爲此調用了motionevent方法。

目前的問題，我不明白爲什麼只有一個對象在下面的代碼中移動。例如與此代碼，只有「不」位圖移動，我想移動兩個位圖獨立彼此。

scenrio：我可以使用我的兩個音符，每個對象一個，獨立移動位圖。但我不知道如何實現這一點。

public class TouchView extends View { 

private Drawable cross; 
private Rect crossBounds = null; 
private Drawable not; 
private Rect notBounds = null; 

private int x1, y1, x2, y2 ; 

boolean flag = true; 

private void intialize() 
{ 
    int w1 = cross.getIntrinsicWidth(); 
    int h1 = cross.getIntrinsicHeight(); 
    x1 = 100; 
    y1 = 100; 
    crossBounds = new Rect(x1-w1/2, y1-w1/2, x1+w1/2, y1+h1/2); 

    int w = not.getIntrinsicWidth(); 
    int h = not.getIntrinsicHeight(); 
    x2 = 300; 
    y2 = 300; 
    notBounds = new Rect(x2-w/2, y2-w/2, x2+w/2, y2+h/2); 

} 

public TouchView(Context context) { 
    super(context); 

    // Get a representation of the image 
    Resources resources = context.getResources(); 
    cross = (Drawable) resources.getDrawable(R.drawable.cross); 
    not = (Drawable) resources.getDrawable(R.drawable.not); 
} 

@Override 
public boolean onTouchEvent(MotionEvent event) { 
    Log.i("TouchView.onTouchEvent", "event = " + event); 

    if(event.getAction() == MotionEvent.ACTION_DOWN || 
      event.getAction() == MotionEvent.ACTION_MOVE) { 

     int touchCounter = event.getPointerCount(); 


     if (touchCounter ==2 && getHeight()==y1){ 
       int w = cross.getIntrinsicWidth(); 
       int h = cross.getIntrinsicHeight(); 
       x1 = (int) event.getX(); 

       crossBounds = new Rect(x1-w/2, y1-w/2, x1+w/2, y1+h/2); 
       } 
       else 
       { 
       int w1 = not.getIntrinsicWidth(); 
       int h1 = not.getIntrinsicHeight(); 
       x2 = (int) event.getX(); 

       notBounds = new Rect(x2-w1/2, y2-w1/2, x2+w1/2, y2+h1/2); 
       } 
       // Request the system to redraw the view (call onDraw at 
       // some point in the future) 
       // From a non-UI thread, call postInvalidate instead 





     invalidate(); 

     return true; 
    } 

    return false; 
} 



@Override 
protected void onDraw(Canvas canvas) { 

    Log.i("TouchView.onDraw", ""); 

    // Background 
    Paint bgPaint = new Paint(); 
    bgPaint.setColor(Color.WHITE); 
    canvas.drawPaint(bgPaint); 

    if (flag == true){ 
     intialize(); 
     cross.setBounds(crossBounds); 
     cross.draw(canvas); 
     not.setBounds(notBounds); 
     not.draw(canvas); 
     flag=false; 
    } 
    if(crossBounds != null) { 
     cross.setBounds(crossBounds); 
     cross.draw(canvas); 
     not.setBounds(notBounds); 
     not.draw(canvas); 
    } 
} 
} 

Answer 1

public class SimpleDrag extends View { 



private final int INVALID_INDEX = -1; 

private final int mTotalItems = 5; 

private ArrayList<Rect> mItemsCollection; 

private ArrayList<Point> mActiveDragPoints; 

private ArrayList<Rect> mActiveRects; 


private Paint mPaint; 

/** 
* @param context 
* @return of type SimpleDrag 
* Constructor function 
* @since Feb 19, 2013 
* @author rajeshcp 
*/ 
public SimpleDrag(Context context) { 
    super(context); 
    init(); 
} 

/** 
* @param context 
* @param attrs 
* @return of type SimpleDrag 
* Constructor function 
* @since Feb 19, 2013 
* @author rajeshcp 
*/ 
public SimpleDrag(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    init(); 
} 

/** 
* @param context 
* @param attrs 
* @param defStyle 
* @return of type SimpleDrag 
* Constructor function 
* @since Feb 19, 2013 
* @author rajeshcp 
*/ 
public SimpleDrag(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    init(); 
} 

/* (non-Javadoc) 
* @see android.view.View#onDraw(android.graphics.Canvas) 
* @since Feb 19, 2013 
* @author rajeshcp 
*/ 
@Override 
protected void onDraw(Canvas canvas) { 
    super.onDraw(canvas); 
    canvas.drawColor(Color.BLUE, PorterDuff.Mode.CLEAR); 
    for(Rect rect : mItemsCollection) 
    { 
     canvas.drawRect(rect, mPaint); 
    } 
} 


/** 
* @param of type null 
* @return of type null 
* function which will initialize the view 
* @since Feb 20, 2013 
* @author rajeshcp 
*/ 
private void init() 
{ 
    mActiveRects  = new ArrayList<Rect>(mTotalItems); 
    mActiveDragPoints = new ArrayList<Point>(mTotalItems); 
    mItemsCollection = new ArrayList<Rect>(); 
    for(int i = 0; i < mTotalItems; i++) 
    { 
     Rect rect = new Rect(i * 100, i * 100, (i + 1) * 100, (i + 1) * 100); 
     mItemsCollection.add(rect); 
    } 
    mPaint  = new Paint(Paint.FILTER_BITMAP_FLAG | Paint.DITHER_FLAG | Paint.ANTI_ALIAS_FLAG); 
    mPaint.setColor(Color.RED); 
} 





/* (non-Javadoc) 
* @see android.view.View#onTouchEvent(android.view.MotionEvent) 
* @since Feb 19, 2013 
* @author rajeshcp 
*/ 
@Override 
public boolean onTouchEvent(MotionEvent event) { 

    final int action = event.getActionMasked(); 
    final int pointer = event.getActionIndex(); 

    switch (action) { 
    case MotionEvent.ACTION_DOWN : 
     Point touchDown = new Point((int)event.getX(), (int)event.getY()); 
     lookForIntersection(touchDown); 
     break; 
    case MotionEvent.ACTION_UP : 
    case MotionEvent.ACTION_CANCEL : 
     mActiveDragPoints.removeAll(mActiveDragPoints); 
     mActiveRects.removeAll(mActiveRects); 
     break; 
    case MotionEvent.ACTION_MOVE : 
     int count = 0; 
     for(Rect rect : mActiveRects) 
     { 
      Point curretPoint = new Point((int)event.getX(count), (int)event.getY(count)); 
      moveRect(curretPoint, mActiveDragPoints.get(count), rect); 
      count++; 
     } 
     Log.d(getClass().getName(), "Active Rects" + mActiveRects.size()); 
     Log.d(getClass().getName(), "Active Points" + mActiveDragPoints.size()); 
     invalidate(); 
     break; 
    case MotionEvent.ACTION_POINTER_DOWN : 
     touchDown = new Point((int)event.getX(pointer), (int)event.getY(pointer)); 
     lookForIntersection(touchDown); 
     //Log.d(getClass().getName(), "ACTION_POINTER_DOWN" + pointer); 
     break; 
    case MotionEvent.ACTION_POINTER_UP : 
     int index = getIntersectionRectIndex(new Point((int)event.getX(pointer), (int)event.getY(pointer))); 
     if(index != INVALID_INDEX) 
     { 
      Rect rect = mItemsCollection.get(index); 
      mActiveDragPoints.remove(mActiveRects.indexOf(rect)); 
      mActiveRects.remove(rect); 
     } 

     break; 

    default: 
     break; 
    } 
    return true; 
} 


/** 
* @param touchDown of type Point 
* @return of type null 
* function which will find the 
* intersecting rect and add to the 
* active collection 
* @since Feb 20, 2013 
* @author rajeshcp 
*/ 
private void lookForIntersection(Point touchDown) 
{ 
    final int index = getIntersectionRectIndex(touchDown); 

    if(index != INVALID_INDEX) 
    { 
     final Rect rect = mItemsCollection.get(index); 
     if(mActiveRects.indexOf(rect) == INVALID_INDEX) 
     { 
      mActiveDragPoints.add(touchDown); 
      mActiveRects.add(mItemsCollection.get(index)); 
     } 
    } 
    Log.d(getClass().getName(), "Active Rects" + mActiveRects.size()); 
    Log.d(getClass().getName(), "Active Points" + mActiveDragPoints.size()); 

} 




/** 
* @param point of type Point 
* @return of type int 
* function which will return the index of 
* the rect contaning the given point 
* @since Feb 20, 2013 
* @author rajeshcp 
*/ 
private int getIntersectionRectIndex(final Point point) 
{ 
    int index = INVALID_INDEX; 
    for(Rect rect : mItemsCollection) 
    { 
     if(rect.contains(point.x, point.y)) 
     { 
      index = mItemsCollection.indexOf(rect); 
      break; 
     } 
    } 
    return index; 
} 


/** 
* @param currentPoint of type Point 
* @param prevPoint of type Point 
* @param rect of type Rect 
* @return of type null 
* function which will move the change the 
* bounds of teh rect 
* @since Feb 20, 2013 
* @author rajeshcp 
*/ 
private void moveRect(Point currentPoint, Point prevPoint, final Rect rect) 
{ 
    int xMoved = currentPoint.x - prevPoint.x; 
    int yMoved = currentPoint.y - prevPoint.y; 
    rect.set(rect.left + xMoved, rect.top + yMoved, rect.right + xMoved, rect.bottom + yMoved); 
    mActiveDragPoints.set(mActiveDragPoints.indexOf(prevPoint), currentPoint); 
} 

} 

希望這是你想要的，沒有測試很多，但基本上這是爲我工作，甚至你可以增加通過更改mTotalItems的NOF項目。希望這會有所幫助。