C++ 如何在 Windows 应用程序中截取屏幕截图？

How can I take a screenshot in a windows application?

提问by user63898

How can I take a screenshot of the current screen using Win32?

如何使用 Win32 截取当前屏幕的屏幕截图？

回答by Woody

// get the device context of the screen
HDC hScreenDC = CreateDC("DISPLAY", NULL, NULL, NULL);     
// and a device context to put it in
HDC hMemoryDC = CreateCompatibleDC(hScreenDC);

int width = GetDeviceCaps(hScreenDC, HORZRES);
int height = GetDeviceCaps(hScreenDC, VERTRES);

// maybe worth checking these are positive values
HBITMAP hBitmap = CreateCompatibleBitmap(hScreenDC, width, height);

// get a new bitmap
HBITMAP hOldBitmap = (HBITMAP) SelectObject(hMemoryDC, hBitmap);

BitBlt(hMemoryDC, 0, 0, width, height, hScreenDC, 0, 0, SRCCOPY);
hBitmap = (HBITMAP) SelectObject(hMemoryDC, hOldBitmap);

// clean up
DeleteDC(hMemoryDC);
DeleteDC(hScreenDC);

// now your image is held in hBitmap. You can save it or do whatever with it

回答by Jerry Coffin

1. Use GetDC(NULL);to get a DC for the entire screen.
2. Use CreateCompatibleDCto create a DC compatible with the screen DC.
3. Use CreateCompatibleBitmapto create a bitmap compatible with the screen DC to hold the result.
4. Use SelectObjectto select the compatible bitmap into the compatible DC.
5. Use BitBltto copy from the screen DC to the compatible DC.
6. Use SelectObjectto deselect the compatible bitmap from the compatible DC.
7. Use DeleteDCto delete the compatible DC.

1. 使用GetDC(NULL);得到一个DC在整个屏幕。
2. 使用CreateCompatibleDC创建与屏幕DC直流兼容。
3. 使用CreateCompatibleBitmap创建与屏幕DC容纳结果兼容的位图。
4. 使用SelectObject选择兼容位图到兼容的DC。
5. 用于BitBlt从屏幕 DC 复制到兼容的 DC。
6. 用于SelectObject从兼容 DC 中取消选择兼容位图。
7. 使用DeleteDC删除兼容DC。

When you create the compatible bitmap, you want it compatible with the screen DC, not the compatible DC.

创建兼容位图时，您希望它与屏幕 DC 兼容，而不是兼容 DC。

For example:

例如：

HDC dcScreen = GetDC(0);
HDC dcTarget = CreateCompatibleDC(dcScreen);
HBITMAP bmpTarget = CreateCompatibleBitmap(dcScreen);
HGDIOBJ oldBmp = SelectObject(dcTarget, bmpTarget);
BitBlt(dcTarget, 0, 0, cx, cy, dcDesktop, x, y, SRCCOPY | CAPTUREBLT);
SelectObject(dcTarget, oldBmp);
DeleteDC(dcTarget);
ReleaseDC(dcScreen);

The other important part is to get the size, and location, of the entire virtual screen:

另一个重要部分是获取整个虚拟屏幕的大小和位置：

int x  = GetSystemMetrics(SM_XVIRTUALSCREEN);  //left (e.g. -1024)
int y  = GetSystemMetrics(SM_YVIRTUALSCREEN);  //top (e.g. -34)
int cx = GetSystemMetrics(SM_CXVIRTUALSCREEN); //entire width (e.g. 2704)
int cy = GetSystemMetrics(SM_CYVIRTUALSCREEN); //entire height (e.g. 1050)

回答by pcunite

void GetScreenShot(void)
{
    int x1, y1, x2, y2, w, h;

    // get screen dimensions
    x1  = GetSystemMetrics(SM_XVIRTUALSCREEN);
    y1  = GetSystemMetrics(SM_YVIRTUALSCREEN);
    x2  = GetSystemMetrics(SM_CXVIRTUALSCREEN);
    y2  = GetSystemMetrics(SM_CYVIRTUALSCREEN);
    w   = x2 - x1;
    h   = y2 - y1;

    // copy screen to bitmap
    HDC     hScreen = GetDC(NULL);
    HDC     hDC     = CreateCompatibleDC(hScreen);
    HBITMAP hBitmap = CreateCompatibleBitmap(hScreen, w, h);
    HGDIOBJ old_obj = SelectObject(hDC, hBitmap);
    BOOL    bRet    = BitBlt(hDC, 0, 0, w, h, hScreen, x1, y1, SRCCOPY);

    // save bitmap to clipboard
    OpenClipboard(NULL);
    EmptyClipboard();
    SetClipboardData(CF_BITMAP, hBitmap);
    CloseClipboard();   

    // clean up
    SelectObject(hDC, old_obj);
    DeleteDC(hDC);
    ReleaseDC(NULL, hScreen);
    DeleteObject(hBitmap);
}

回答by Govind Parmar

Full code for saving a raw 24-bit lossless bitmap of all monitors at the current window station using Windows API:

使用 Windows API 在当前窗口站保存所有显示器的原始 24 位无损位图的完整代码：

BOOL WINAPI SaveBitmap(WCHAR *wPath)
{
    BITMAPFILEHEADER bfHeader;
    BITMAPINFOHEADER biHeader;
    BITMAPINFO bInfo;
    HGDIOBJ hTempBitmap;
    HBITMAP hBitmap;
    BITMAP bAllDesktops;
    HDC hDC, hMemDC;
    LONG lWidth, lHeight;
    BYTE *bBits = NULL;
    HANDLE hHeap = GetProcessHeap();
    DWORD cbBits, dwWritten = 0;
    HANDLE hFile;
    INT x = GetSystemMetrics(SM_XVIRTUALSCREEN);
    INT y = GetSystemMetrics(SM_YVIRTUALSCREEN);

    ZeroMemory(&bfHeader, sizeof(BITMAPFILEHEADER));
    ZeroMemory(&biHeader, sizeof(BITMAPINFOHEADER));
    ZeroMemory(&bInfo, sizeof(BITMAPINFO));
    ZeroMemory(&bAllDesktops, sizeof(BITMAP));

    hDC = GetDC(NULL);
    hTempBitmap = GetCurrentObject(hDC, OBJ_BITMAP);
    GetObjectW(hTempBitmap, sizeof(BITMAP), &bAllDesktops);

    lWidth = bAllDesktops.bmWidth;
    lHeight = bAllDesktops.bmHeight;

    DeleteObject(hTempBitmap);

    bfHeader.bfType = (WORD)('B' | ('M' << 8));
    bfHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
    biHeader.biSize = sizeof(BITMAPINFOHEADER);
    biHeader.biBitCount = 24;
    biHeader.biCompression = BI_RGB;
    biHeader.biPlanes = 1;
    biHeader.biWidth = lWidth;
    biHeader.biHeight = lHeight;

    bInfo.bmiHeader = biHeader;

    cbBits = (((24 * lWidth + 31)&~31) / 8) * lHeight;

    hMemDC = CreateCompatibleDC(hDC);
    hBitmap = CreateDIBSection(hDC, &bInfo, DIB_RGB_COLORS, (VOID **)&bBits, NULL, 0);
    SelectObject(hMemDC, hBitmap);
    BitBlt(hMemDC, 0, 0, lWidth, lHeight, hDC, x, y, SRCCOPY);


    hFile = CreateFileW(wPath, GENERIC_WRITE | GENERIC_READ, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    WriteFile(hFile, &bfHeader, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
    WriteFile(hFile, &biHeader, sizeof(BITMAPINFOHEADER), &dwWritten, NULL);
    WriteFile(hFile, bBits, cbBits, &dwWritten, NULL);

    CloseHandle(hFile);

    DeleteDC(hMemDC);
    ReleaseDC(NULL, hDC);
    DeleteObject(hBitmap);

    return TRUE;
}

回答by Bob Moore

There is a MSDN sample, Capturing an Image, for capturing an arbitrary HWND to a DC (you could try passing the output from GetDesktopWindow to this). But how well this will work under the new desktop compositor on Vista/Windows 7, I don't know.

有一个 MSDN 示例，捕获图像，用于将任意 HWND 捕获到 DC（您可以尝试将 GetDesktopWindow 的输出传递给它）。但我不知道这在 Vista/Windows 7 上的新桌面合成器下的工作情况如何。