Question

我在我的应用程序中尝试过捏缩放和拖动。我面临两个问题。 1.在第一次触摸时，图像移动到其他位置。拖动动作从该改变的位置起作用。 2.在缩放图像时反弹到特定位置，拖动动作适用于跳转后的特定边界。此问题有时不常发生。这是我的代码

  public boolean onTouch(View v, MotionEvent event) {
    ImageView view = (ImageView) v;
    view.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;
            break;
        case MotionEvent.ACTION_UP: //first finger lifted
        case MotionEvent.ACTION_POINTER_UP: //second finger lifted
            mode = NONE;
            Log.d(TAG, "mode=NONE" );
            break;
        case MotionEvent.ACTION_POINTER_DOWN: //second finger down
            oldDist = spacing(event);
            Log.d(TAG, "oldDist=" + oldDist);
            if (oldDist > 5f) {
                savedMatrix.set(matrix);
                midPoint(mid, event);
                mode = ZOOM;
                Log.d(TAG, "mode=ZOOM" );
            }
            break;

        case MotionEvent.ACTION_MOVE:
            if (mode == DRAG) { //movement of first finger


                matrix.set(savedMatrix);
                float dx = event.getX() - start.x;
                float dy = event.getY() - start.y;
                matrix.postTranslate(dx, dy);

                /*if (view.getLeft() >= -392){
                    matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);
                }*/
            }
            else if (mode == ZOOM) { //pinch zooming
                float newDist = spacing(event);
                Log.d(TAG, "newDist=" + newDist);
                if (newDist > 5f) {
                    matrix.set(savedMatrix);
                    scale = newDist / oldDist;
                    matrix.postScale(scale, scale, mid.x, mid.y);
                }
            }
            break;
    }

    // Perform the transformation
    view.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 (float)Math.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());
}

Answer 1

如果要在imageview上使用缩放图像，则可以使用PhotoView库。

捏变焦反弹到android中的特定位置

1 个答案: