在画布上缩放和转换图像的android绘制线

Question

我有问题在画布上的缩放和变换图像上绘制线条，以及转换后我能够在图像上绘制线条，但如果图像缩放（放大或缩小），则线条使用手指触摸意外地绘制了像素。由于我正在从事油漆应用，但对此没有更多的了解，所以我需要你的帮助，我在谷歌搜索但没有运气，我没有找到任何东西

这里的图像是第一个默认正常工作，第二个移动的图像正常工作正确划线

虽然在缩放图像上的第三个没有正确绘制，但我的意思是如果从顶部/左角开始绘制然后线绘制点与此处不同

如果您需要代码然后说出来我会编辑问题

Answer 1

好多次实施后我得到了解决方案。

这是我在onDraw（）

中绘图的代码

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

    canvas.drawBitmap(MoveImageTestActivity.bmp, 0,0,null);
    if(mScaleFactor!=1.f)
        canvas.restore();

    if(isDrawing)
        canvas.drawPath(tempPath,get_paint());

    if(mScaleFactor==1.f)
        canvas.restore();
}

这里你必须检查恢复画布的比例因子值。如果比例因子值是默认值1.f而图像只是移动然后在绘制线/路径后恢复，如果比例因子不等于1.f（默认值）然后恢复画布1然后绘制线/使用手指触摸绘图时间的路径。

这是我的onTouch（）代码

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

        if(isDrawing){
            float dx = ev.getX();
            float dy = ev.getY();;

            if(mScaleFactor==1.f){
                dx = ev.getX() - mPosX;
                dy = ev.getY() - mPosY;
            }
            tempPath = new Path();
            tempPath.moveTo(dx,dy);
        }else{
            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
        if(isDrawing){
            float dx = ev.getX();
            float dy = ev.getY();;

            if(mScaleFactor==1.f){
                dx = ev.getX() - mPosX;
                dy = ev.getY() - mPosY;
            }
            tempPath.lineTo(dx,dy);
        }else{
            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;
        }
        break;
    }
    case MotionEvent.ACTION_UP: {
        points.clear();
        mActivePointerId = INVALID_POINTER_ID;
        break;
    }

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

    case MotionEvent.ACTION_POINTER_UP: {
        if(!isDrawing){
            // 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;
    }
    }
    invalidate();
    return true;
}