来自stretchblt的奇怪结果取决于尺寸

Question

所以我正在玩stretchblt，当我部分捕捉到我的屏幕时，我注意到了一种奇怪的相关性。只要捕获的尺寸匹配常用的分辨率（比如{0,0,224,144}的RECT），我会得到这样的结果： 244x144 Res

但是，如果我将尺寸更改一个像素（比如{0,0,225,144}的RECT），我会得到这样的结果：255x144

这是一个代码示例，如果有必要的话。我真的可以使用一些洞察力来解释为什么会这样。谢谢你的帮助！

    void CaptureScreen(RECT imageDim, std::vector<uint8_t>& vecData)
{
    BYTE* pScreenData = nullptr;
    LONG mapWidth = imageDim.right - imageDim.left;
    LONG mapHeight = imageDim.bottom - imageDim.top;

    HDC desktopDC = GetDC(NULL);
    HDC captureDC = CreateCompatibleDC(desktopDC);

    BITMAPINFO bmpInfo;
    bmpInfo.bmiHeader.biSize = sizeof(bmpInfo.bmiHeader);
    bmpInfo.bmiHeader.biPlanes = 1;
    bmpInfo.bmiHeader.biBitCount = 24;
    bmpInfo.bmiHeader.biCompression = BI_RGB;
    bmpInfo.bmiHeader.biClrUsed = 0;
    bmpInfo.bmiHeader.biClrImportant = 0;
    bmpInfo.bmiHeader.biWidth = mapWidth;
    bmpInfo.bmiHeader.biHeight = mapHeight;
    bmpInfo.bmiHeader.biSizeImage = mapWidth*mapHeight * 3;

    HBITMAP hBitmap = CreateDIBSection(captureDC, &bmpInfo, DIB_RGB_COLORS, (void**)(&pScreenData), NULL, NULL);

    SelectObject(captureDC, hBitmap);

    StretchBlt(captureDC,   // Destination device context
        0,                                  // x-coordinate of destination rect
        mapHeight,                                  // y-coordinate of destination rect
        mapWidth,                           // width of destination rect
        -mapHeight,                         // height of destination rect
        desktopDC,                  // Desktop device context
        imageDim.left,                      // x-coordinate of source rectangle
        imageDim.top,                       // y-coordinate of source rectangle
        mapWidth,                           // width of source rect
        mapHeight,                          // height of source rect
        SRCCOPY);

    DeleteObject(hBitmap);

    SaveImage(pScreenData, imageDim);
}