android - 我的 Android 手指绘画应用程序将绘画发送到图像上的不规则位置

Question

在我的 Android Finger Paint 应用程序中，我使用了两个 View 的 imageview backside 和 paintview on top，它可以很好地进行绘画和删除。但是保存后真正的绘画位置发生了变化。

删除了图像的无效链接

代码是

public MyView(Context c)  {
    super(c);
    //mBitmap = Bitmap.createScaledBitmap(originalBitmap,bw,bh,true);
    mBitmap = Bitmap.createBitmap(bw,bh,Bitmap.Config.ARGB_8888);
    mCanvas = new Canvas(mBitmap);
    mPath = new Path();
    mBitmapPaint = new Paint(Paint.DITHER_FLAG);
    mBitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
}
@Override 
protected void onDraw(Canvas canvas) {   
    canvas.drawColor(Color.TRANSPARENT);
    canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
    canvas.drawPath(mPath, mPaint);
} 

myimage.setOnTouchListener(this);
public boolean onTouch(View v, MotionEvent event) {
    ImageView myimage = (ImageView) v;
    // Dump touch event to log
    dumpEvent(event);
    // Handle touch events here...
    switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            savedMatrix.set(matrix);
            start.set(event.getX(), event.getY());
            Log.d(TAG, "mode=DRAG");
            mode = DRAG;
            break;
        case MotionEvent.ACTION_POINTER_DOWN:
            oldDist = spacing(event);
            Log.d(TAG, "oldDist=" + oldDist);
            if (oldDist > 10f) {
                savedMatrix.set(matrix);
                midPoint(mid, event);
                mode = ZOOM;
                Log.d(TAG, "mode=ZOOM");
            }
            break;
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_POINTER_UP:
            mode = NONE;
            Log.d(TAG, "mode=NONE");
            break;
        case MotionEvent.ACTION_MOVE:
            if (mode == DRAG) {
                /////// limiting  the panning 
                matrix.getValues(matrixValues);
                float currentY = matrixValues[Matrix.MTRANS_Y];
                float currentX = matrixValues[Matrix.MTRANS_X];
                float currentScale = matrixValues[Matrix.MSCALE_X];
                float currentHeight = height * currentScale;
                float currentWidth = width * currentScale;
                float dx = event.getX() - start.x;
                float dy = event.getY() - start.y;
                float newX = currentX+dx;
                float newY = currentY+dy;   
                RectF drawingRect = new RectF(newX, newY, newX+currentWidth, newY+currentHeight);
                float diffUp = Math.min(viewRect.bottom-drawingRect.bottom, viewRect.top-drawingRect.top);
                float diffDown = Math.max(viewRect.bottom-drawingRect.bottom, viewRect.top-drawingRect.top);
                float diffLeft = Math.min(viewRect.left-drawingRect.left, viewRect.right-drawingRect.right);
                float diffRight = Math.max(viewRect.left-drawingRect.left, viewRect.right-drawingRect.right);
                if(diffUp > 0 ){ dy +=diffUp; }
                if(diffDown < 0){ dy +=diffDown; }  
                if( diffLeft> 0){ dx += diffLeft; }
                if(diffRight < 0){dx += diffRight; }
                matrix.postTranslate(dx, dy);
            } 
            else if (mode == ZOOM) {
                float newDist = spacing(event);
                Log.d(TAG, "newDist=" + newDist);
                if (newDist > 10f) {
                matrix.set(savedMatrix);
                float scale = newDist / oldDist;
                matrix.getValues(matrixValues);
                float currentScale = matrixValues[Matrix.MSCALE_X];
                // limit zoom
                if (scale * currentScale > maxZoom) {
                    scale = maxZoom / currentScale; 
                }
                else if(scale * currentScale < minZoom){
                    scale = minZoom / currentScale; 
                }
                matrix.postScale(scale, scale, mid.x, mid.y);
            }
        }
        break;
    }
    myimage.setImageMatrix(matrix);
    return true; // indicate event was handled
}

// 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());
    }

    //Determine the space between the first two fingers
    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);
    }

    // Calculate the mid point of the first 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);
    }
}

Answer 1

位置不会改变!如果您仔细查看链接的图像，您会发现您的手指画不会相对于照片的角移动。换句话说，您保存的是绘图相对于屏幕的位置，而不是相对于照片当前滚动位置的位置。

保存时，必须考虑背景照片被裁剪和/或缩放的事实。