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'正在开发一个应用程序，我在其中粘贴图像，在画布上进行绘图和绘画。这个应用程序还可以放大/缩小画布或将其拖动到不同的位置。我的问题是：缩放或拖动画布后我无法获得正确的画布坐标。我想在画布缩放或拖动后绘制手指画但无法检索我触摸过的正确位置......

@Override
public boolean onTouchEvent(MotionEvent event) {

    scaleListener.onTouchEvent(event);

    synchronized(thread.getSurfaceHolder()){

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

            case MotionEvent.ACTION_DOWN :
                // Remember our initial down event location.
                savedMatrix.set(m_matrix);
                start.set(event.getX() , event.getY());
                mode = DRAG;                
            break;

            case MotionEvent.ACTION_POINTER_DOWN :

                oldDist = spacing(event);
                if (oldDist > 10f) {

                    savedMatrix.set(m_matrix);
                    m_matrix.getValues(matrixValues);
                    midPoint(mid, event);
                    mode = ZOOM;
                }

             break;

            case MotionEvent.ACTION_UP :
            case MotionEvent.ACTION_POINTER_UP :
                    mode = NONE;

            break;

            case MotionEvent.ACTION_MOVE :

                if(mode==DRAG && isDragAllowd){
                        m_matrix.set(savedMatrix);
                        rebound(event.getX() , event.getY());
                }
                else if(mode==ZOOM){

                    float newDist = spacing(event);
                    if (newDist > 10f){

                            m_matrix.set(savedMatrix);

                            float scale = newDist/oldDist;
                            m_matrix.getValues(matrixValues);
                            float currentScale = matrixValues[Matrix.MSCALE_X];

                            // limit zoom
                            if (scale * currentScale > maxZoom){
                                    scale = maxZoom / currentScale;
                                    //scale = maxZoom;
                            }
                            else if (scale * currentScale < minZoom){
                                    scale = minZoom / currentScale;
                                    //scale = minZoom;
                            }

                            m_matrix.postScale(scale, scale, mid.x, mid.y);
                            m_matrix.getValues(matrixValues);

                  }

            }
       break;

    }

    return true; //done with this event so consume it


    }       

}

@Override
protected void onDraw(Canvas canvas){
    super.onDraw(canvas);

            canvas.drawColor(Color.WHITE);
        canvas.drawBitmap(currentBitmap, m_matrix, null);
        c2.drawColor(Color.BLACK); 
        commandManager.executeAll(c2); // Drawing all the Paints on Canvas c2
        // Overlay bitmap it's a transparent layour 
            canvas.drawBitmap(overlayBitmap, 0, 0, pTouch);

}

当用户缩放位图时，他无法在其上绘制，缩放后绘图不会发生在适当的位置。

4

1 回答 1

3

使用以下等式转换点，之后用户在缩放期间或滚动后不会遇到任何绘画困难。

 float f1 = (( motionEvent.getX() - m_transformedPoints[0] )/( m_transformedPoints[2] - m_transformedPoints[0] ))*currentBitmapWidth;
     float f2 = (( motionEvent.getY() - m_transformedPoints[1] )/( m_transformedPoints[3] - m_transformedPoints[1] ))*currentBitmapHeight; 

    //calculate the transformed view in onDraw Method
    this.m_transformedPoints[0] = 0.0F;
    this.m_transformedPoints[1] = 0.0F;
    this.m_transformedPoints[2] = currentBitmapWidth;
    this.m_transformedPoints[3] = currentBitmapHeight;
    this.m_matrix.mapPoints(this.m_transformedPoints);
于 2012-09-13T11:25:47.413 回答