可缩放列表视图不滚动

Question

我有一个问题：我的自定义列表视图在缩放之前不滚动。缩放按预期工作。我该如何解决这个问题？

ZoomableListView：

public class ZoomableListView extends ListView { 

private ScaleGestureDetector mScaleDetector; 
private float mScaleFactor = 1.f; 
private boolean isPagerEnabled; 
private static final int INVALID_POINTER_ID = -1; 

// The ‘active pointer’ is the one currently moving our object. 
private int mActivePointerId = INVALID_POINTER_ID; 

private float mPosX; 
private float mPosY; 

private float mLastTouchX; 
private float mLastTouchY; 

// Pivot point for Scaling 
static float gx = 0, gy = 0; 

public ZoomableListView(Context context, AttributeSet attrs) { 
super(context, attrs); 
mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener()); 
} 

public ZoomableListView(Context context) { 
super(context); 
mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener()); 
} 

@Override 
public void onDraw(Canvas canvas) { 
super.onDraw(canvas); 
canvas.save(Canvas.MATRIX_SAVE_FLAG); 
canvas.translate(mPosX, mPosY); 
canvas.scale(mScaleFactor, mScaleFactor); 
canvas.restore(); 
} 


@Override 
protected void dispatchDraw(Canvas canvas) { 
// Save the canvas to set the scaling factor returned from detector 
canvas.save(Canvas.MATRIX_SAVE_FLAG); 
if (mScaleFactor == 1.0f) { 
    isPagerEnabled = true; 
} else { 
    isPagerEnabled = false; 
} 

if (mScaleFactor == 1.0f) { 
    mPosX = 0.0f; 
    mPosY = 0.0f; 
} 
canvas.translate(mPosX, mPosY); 
canvas.scale(mScaleFactor, mScaleFactor); 
super.dispatchDraw(canvas); 
canvas.restore(); 
invalidate(); 
} 

@Override 
public boolean onTouchEvent(MotionEvent ev) { 
final int action = ev.getAction(); 
mScaleDetector.onTouchEvent(ev); 
switch (action & MotionEvent.ACTION_MASK) { 
case MotionEvent.ACTION_DOWN: { 
    final float x = ev.getX(); 
    final float y = ev.getY(); 

    mLastTouchX = x; 
    mLastTouchY = y; 

    // Save the ID of this pointer 
    mActivePointerId = ev.getPointerId(0); 
    break; 
} 

case MotionEvent.ACTION_MOVE: { 
    // Find the index of the active pointer and fetch its position 
    final int pointerIndex = ev.findPointerIndex(mActivePointerId); 
    final float x = ev.getX(pointerIndex); 
    final float y = ev.getY(pointerIndex); 

    final float dx = x - mLastTouchX; 
    final float dy = y - mLastTouchY; 

    mPosX += dx; 
    mPosY += dy; 

    mLastTouchX = x; 
    mLastTouchY = y; 

    invalidate(); 
    break; 
} 

case MotionEvent.ACTION_UP: { 
    mActivePointerId = INVALID_POINTER_ID; 
    break; 
} 

case MotionEvent.ACTION_CANCEL: { 
    mActivePointerId = INVALID_POINTER_ID; 
    break; 
} 

case MotionEvent.ACTION_POINTER_UP: { 
    // Extract the index of the pointer that left the touch sensor 
    final int pointerIndex = (action & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT; 
    final int pointerId = ev.getPointerId(pointerIndex); 
    if (pointerId == mActivePointerId) { 
    // This was our active pointer going up. Choose a new 
    // active pointer and adjust accordingly. 
    final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 
    mLastTouchX = ev.getX(newPointerIndex); 
    mLastTouchY = ev.getY(newPointerIndex); 
    mActivePointerId = ev.getPointerId(newPointerIndex); 
    } 
    break; 
} 
} 

return true; 
} 

private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener { 
@Override 
public boolean onScale(ScaleGestureDetector detector) { 
    mScaleFactor *= detector.getScaleFactor(); 

    // Don't let the object get too small or too large. 
    mScaleFactor = Math.max(1.0f, Math.min(mScaleFactor, 3.0f)); 

    invalidate(); 
    return true; 
} 
} 

}

这是自定义列表视图的XML：

<com.android.app.core.view.ZoomableListView 
    android:id="@android:id/list" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_marginBottom="40dp" 
    android:divider="@android:color/darker_gray" 
    android:dividerHeight="1dp" > 
</com.android.app.core.view.ZoomableListView> 

感谢的任何答复。

Answer 1

尝试添加super.onTouchEvent(ev);。我试了一下，以确认它的工作：

​​

Answer 2

请添加这些行

@Override 
public boolean onTouchEvent(MotionEvent ev) { 
    // Let the ScaleGestureDetector inspect all events. 
    mScaleDetector.onTouchEvent(ev); 
    return true; 
} 

有这个

<com.android.app.core.view.ZoomableListView 
    android:id="@android:id/list" 
    android:layout_width="fill_parent" 
      android:layout_height="fill_parent" 
    android:layout_marginBottom="40dp" 
    android:divider="@android:color/darker_gray" 
    android:dividerHeight="1dp" > 
</com.android.app.core.view.ZoomableListView>