Question

我尝试使用我一直用于PrintWindow

的方法捕获窗口

RECT rc;
GetClientRect(hwnd, out rc); //The process window handler

Bitmap bmp = new Bitmap(rc.right, rc.bottom, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
Graphics gfxBmp = Graphics.FromImage(bmp);
IntPtr hdcBitmap = gfxBmp.GetHdc();

PrintWindow(hwnd, hdcBitmap, 1);

gfxBmp.ReleaseHdc(hdcBitmap);
gfxBmp.Dispose();
bmp.Save("test.png");

问题在于，在这个特定的游戏过程中，当窗口调用Printwindow函数时，窗口会非常快，因此有时保存的图像是完全白色的。

所以我尝试使用BitBlt：

Bitmap bmp = new Bitmap(rc.right, rc.bottom, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
Graphics gfxBmp = Graphics.FromImage(bmp);
IntPtr dest = gfxBmp.GetHdc();
IntPtr source = GetWindowDC(hwnd);

BitBlt(dest, 0, 0, rc.width, rc.height, source, 0, 0, 13369376);
bmp.Save("test.png");

但使用保存图像上方的代码完全是黑色的。

有任何方法可以阻止PrintWindow使进程窗口轻弹＆＃34;白色层＆＃34; ？如果可能BitBtl应该为我解决这个问题吧？但是我的代码有什么问题？

谢谢

Answer 1

您可以尝试使用此代码，它对我有用。如果您仍然看到黑色图像，可能您需要使用DWM解决方案。

更新：修复缺失的窗口参数

    public Bitmap CaptureWindowImage(IntPtr hWnd, System.Drawing.Rectangle wndRect)
    {
        IntPtr hWndDc = GetDC(hWnd);
        IntPtr hMemDc = CreateCompatibleDC(hWndDc);
        IntPtr hBitmap = CreateCompatibleBitmap(hWndDc, wndRect.Width, wndRect.Height);
        SelectObject(hMemDc, hBitmap);

        BitBlt(hMemDc, 0, 0, wndRect.Width, wndRect.Height, hWndDc, 0, 0, TernaryRasterOperations.SRCCOPY);
        Bitmap bitmap = Bitmap.FromHbitmap(hBitmap);

        DeleteObject(hBitmap);
        ReleaseDC(window.hWnd, hWndDc);
        ReleaseDC(IntPtr.Zero, hMemDc);

        return bitmap;
    }

    private enum TernaryRasterOperations : uint
    {
        /// <summary>dest = source</summary>
        SRCCOPY = 0x00CC0020,
        /// <summary>dest = source OR dest</summary>
        SRCPAINT = 0x00EE0086,
        /// <summary>dest = source AND dest</summary>
        SRCAND = 0x008800C6,
        /// <summary>dest = source XOR dest</summary>
        SRCINVERT = 0x00660046,
        /// <summary>dest = source AND (NOT dest)</summary>
        SRCERASE = 0x00440328,
        /// <summary>dest = (NOT source)</summary>
        NOTSRCCOPY = 0x00330008,
        /// <summary>dest = (NOT src) AND (NOT dest)</summary>
        NOTSRCERASE = 0x001100A6,
        /// <summary>dest = (source AND pattern)</summary>
        MERGECOPY = 0x00C000CA,
        /// <summary>dest = (NOT source) OR dest</summary>
        MERGEPAINT = 0x00BB0226,
        /// <summary>dest = pattern</summary>
        PATCOPY = 0x00F00021,
        /// <summary>dest = DPSnoo</summary>
        PATPAINT = 0x00FB0A09,
        /// <summary>dest = pattern XOR dest</summary>
        PATINVERT = 0x005A0049,
        /// <summary>dest = (NOT dest)</summary>
        DSTINVERT = 0x00550009,
        /// <summary>dest = BLACK</summary>
        BLACKNESS = 0x00000042,
        /// <summary>dest = WHITE</summary>
        WHITENESS = 0x00FF0062
    }

    [DllImport("gdi32.dll", ExactSpelling = true, PreserveSig = true, SetLastError = true)]
    static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);

    [DllImport("gdi32.dll")]
    private static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight);

    [DllImport("gdi32.dll", SetLastError = true)]
    private static extern IntPtr CreateCompatibleDC(IntPtr hdc);

    [DllImport("gdi32.dll")]
    private static extern bool DeleteObject(IntPtr hObject);

    [DllImport("gdi32.dll")]
    private static extern IntPtr CreateBitmap(int nWidth, int nHeight, uint cPlanes, uint cBitsPerPel, IntPtr lpvBits);

    [DllImport("user32.dll")]
    private static extern IntPtr GetDC(IntPtr hWnd);

    [DllImport("user32.dll")]
    private static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);

    [DllImport("gdi32.dll")]
    private static extern bool BitBlt(IntPtr hdc, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hdcSrc, int nXSrc, int nYSrc, TernaryRasterOperations dwRop);

Answer 2

弗朗切斯科的答案几乎奏效，但是由于尝试调用ReleaseDC(IntPtr.Zero, hMemDc);而导致内存泄漏，如果调用DeleteDC(hMemDc);则不会泄漏。

https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-releasedc

对于每次调用，应用程序必须调用ReleaseDC函数。 GetWindowDC函数以及对于每次调用GetDC函数的检索公共DC。

应用程序无法使用ReleaseDC功能来释放DC 是通过调用 CreateDC函数创建的；相反，它必须使用 DeleteDC函数。 必须从与该线程相同的线程中调用ReleaseDC。称为GetDC。

已通过任务管理器中GDI Objects的数量以及内存使用情况进行了验证

PrintWindow闪烁

2 个答案: