GDI快速遍历位图像素

使用DIB部分可直接快速访问像素

例如，此测试将记事本中的所有白色像素替换为绿色像素

HDC hDCScreen = GetDC(NULL);
        HWND hWndDest = FindWindow(L"Notepad", NULL);
        if (hWndDest)
        {
            if (IsIconic(hWndDest))
            {
                ShowWindow(hWndDest, SW_RESTORE);
                Sleep(100);
            }
            RECT rect;
            GetWindowRect(hWndDest, &rect);
            int nWidth = rect.right - rect.left;
            int nHeight = rect.bottom - rect.top;

            HDC hDC = GetDC(hWndDest);
            HDC hCaptureDC = CreateCompatibleDC(hDCScreen);
            HBITMAP hCaptureBitmap = CreateCompatibleBitmap(hDCScreen, nWidth, nHeight);
            HGDIOBJ hOldBitmap = SelectObject(hCaptureDC, hCaptureBitmap);
            PrintWindow(hWndDest, hCaptureDC, PW_RENDERFULLCONTENT);
            HDC hDCMem = CreateCompatibleDC(hDC);
            HBITMAP hBitmapOld;
            BITMAPINFO bi = { 0 };
            bi.bmiHeader.biSize = sizeof(bi.bmiHeader);
            bi.bmiHeader.biWidth = nWidth;
            bi.bmiHeader.biHeight = nHeight;
            bi.bmiHeader.biPlanes = 1;
            bi.bmiHeader.biBitCount = 32;
            bi.bmiHeader.biCompression = BI_RGB;
            BYTE *pbBitmap;
            HBITMAP hBitmap = CreateDIBSection(hDCMem, &bi, DIB_RGB_COLORS, (void**)&pbBitmap, NULL, 0);
            if (hBitmap)
            {
                hBitmapOld = (HBITMAP)SelectObject(hDCMem, hBitmap);
                BitBlt(hDCMem, 0, 0, nWidth, nHeight, hCaptureDC, 0, 0, SRCCOPY);

                RGBQUAD *pRGB;
                LONG nPixels;
                for (pRGB = (RGBQUAD *)pbBitmap, nPixels = nWidth * nHeight; nPixels > 0; ++pRGB, --nPixels)
                {
                    ULONG nRed = pRGB->rgbRed;
                    ULONG nGreen = pRGB->rgbGreen;
                    ULONG nBlue = pRGB->rgbBlue;

                    if (nRed == 255 && nGreen == 255 && nBlue == 255)
                    {
                        pRGB->rgbRed = 0;
                        pRGB->rgbGreen = 255;
                        pRGB->rgbBlue = 0;
                    }
                }
                // Test copy to screen
                BitBlt(hDCScreen, 0, 0, nWidth, nHeight, hDCMem, 0, 0, SRCCOPY);
                SelectObject(hDCMem, hBitmapOld);
                DeleteObject(hBitmap);
            }
            DeleteDC(hDCMem);

            hOldBitmap = SelectObject(hCaptureDC, hOldBitmap);
            DeleteDC(hCaptureDC);
            DeleteObject(hCaptureBitmap);
            ReleaseDC(hWndDest, hDC);               
        }
        ReleaseDC(NULL, hDCScreen);

参考： https://stackoverflow.com/questions/57078206/how-to-iterate-through-bitmap-pixels/57081780#57081780