C++屏幕截图

Question

如何使用C++捕获屏幕截图？我将与Win32一起工作。

请不要使用MFC代码。

Answer 1

#include "windows.h" // should be less than and greater than instead of \" 

int CaptureBMP(LPCTSTR szFile) 
{ 
    // Source[1] 
    HDC hdcScr, hdcMem; 
    HBITMAP hbmScr; 
    BITMAP bmp; 
    int iXRes, iYRes; 

    // Create a normal DC and a memory DC for the entire screen. The 
    // normal DC provides a "snapshot" of the screen contents. The 
    // memory DC keeps a copy of this "snapshot" in the associated 
    // bitmap. 
    hdcScr = CreateDC("DISPLAY", NULL, NULL, NULL); 
    hdcMem = CreateCompatibleDC(hdcScr); 

    iXRes = GetDeviceCaps(hdcScr, HORZRES); 
    iYRes = GetDeviceCaps(hdcScr, VERTRES); 

    // Create a compatible bitmap for hdcScreen. 
    hbmScr = CreateCompatibleBitmap(hdcScr, iXRes, iYRes); 
    if (hbmScr == 0) return 0; 

    // Select the bitmaps into the compatible DC. 
    if (!SelectObject(hdcMem, hbmScr)) return 0; 

    // Copy color data for the entire display into a 
    // bitmap that is selected into a compatible DC. 
    if (!StretchBlt(hdcMem, 
     0, 0, iXRes, iYRes, 
     hdcScr, 
     0, 0, iXRes, iYRes, 
     SRCCOPY)) 

     return 0; 

    // Source[2] 
    PBITMAPINFO pbmi; 
    WORD cClrBits; 

    // Retrieve the bitmap's color format, width, and height. 
    if (!GetObject(hbmScr, sizeof(BITMAP), (LPSTR) &bmp)) return 0; 

    // Convert the color format to a count of bits. 
    cClrBits = (WORD)(bmp.bmPlanes * bmp.bmBitsPixel); 
    if (cClrBits == 1) 
     cClrBits = 1; 
    else if (cClrBits <= 4) 
     cClrBits = 4; 
    else if (cClrBits <= 8) 
     cClrBits = 8; 
    else if (cClrBits <= 16) 
     cClrBits = 16; 
    else if (cClrBits <= 24) 
     cClrBits = 24; 
    else cClrBits = 32; 

    // Allocate memory for the BITMAPINFO structure. (This structure 
    // contains a BITMAPINFOHEADER structure and an array of RGBQUAD 
    // data structures.) 
    if (cClrBits != 24) 
     pbmi = (PBITMAPINFO) LocalAlloc(LPTR, 
       sizeof(BITMAPINFOHEADER) + 
       sizeof(RGBQUAD) * (1 << cClrBits)); 

    // There is no RGBQUAD array for the 24-bit-per-pixel format. 
    else 
     pbmi = (PBITMAPINFO) LocalAlloc(LPTR, 
       sizeof(BITMAPINFOHEADER)); 

    // Initialize the fields in the BITMAPINFO structure. 
    pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER); 
    pbmi->bmiHeader.biWidth = bmp.bmWidth; 
    pbmi->bmiHeader.biHeight = bmp.bmHeight; 
    pbmi->bmiHeader.biPlanes = bmp.bmPlanes; 
    pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel; 
    if (cClrBits < 24) 
     pbmi->bmiHeader.biClrUsed = (1 << cClrBits); 

    // If the bitmap is not compressed, set the BI_RGB flag. 
    pbmi->bmiHeader.biCompression = BI_RGB; 

    // Compute the number of bytes in the array of color 
    // indices and store the result in biSizeImage. 
    pbmi->bmiHeader.biSizeImage = (pbmi->bmiHeader.biWidth + 7)/8 
            * pbmi->bmiHeader.biHeight * cClrBits; 

    // Set biClrImportant to 0, indicating that all of the 
    // device colors are important. 
    pbmi->bmiHeader.biClrImportant = 0; 

    HANDLE hf;     // file handle 
    BITMAPFILEHEADER hdr;  // bitmap file-header 
    PBITMAPINFOHEADER pbih;  // bitmap info-header 
    LPBYTE lpBits;    // memory pointer 
    DWORD dwTotal;    // total count of bytes 
    DWORD cb;     // incremental count of bytes 
    BYTE *hp;     // byte pointer 
    DWORD dwTmp; 

    pbih = (PBITMAPINFOHEADER) pbmi; 
    lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, pbih->biSizeImage); 

    if (!lpBits) return 0; 

    // Retrieve the color table (RGBQUAD array) and the bits 
    // (array of palette indices) from the DIB. 
    if (!GetDIBits(hdcMem, hbmScr, 0, (WORD) pbih->biHeight, lpBits, pbmi, DIB_RGB_COLORS)) return 0; 

    // Create the .BMP file. 
    hf = CreateFile(szFile, 
        GENERIC_READ | GENERIC_WRITE, 
        (DWORD) 0, 
        NULL, 
        CREATE_ALWAYS, 
        FILE_ATTRIBUTE_NORMAL, 
        (HANDLE) NULL); 
    if (hf == INVALID_HANDLE_VALUE) return 0; 

    hdr.bfType = 0x4d42;  // 0x42 = "B" 0x4d = "M" 

    // Compute the size of the entire file. 
    hdr.bfSize = (DWORD) (sizeof(BITMAPFILEHEADER) + 
       pbih->biSize + pbih->biClrUsed * 
       sizeof(RGBQUAD) + pbih->biSizeImage); 
    hdr.bfReserved1 = 0; 
    hdr.bfReserved2 = 0; 

    // Compute the offset to the array of color indices. 
    hdr.bfOffBits = (DWORD) sizeof(BITMAPFILEHEADER) + 
        pbih->biSize + pbih->biClrUsed * 
        sizeof (RGBQUAD); 

    // Copy the BITMAPFILEHEADER into the .BMP file. 
    if (!WriteFile(hf, (LPVOID) &hdr, sizeof(BITMAPFILEHEADER), (LPDWORD) &dwTmp, NULL)) return 0; 

    // Copy the BITMAPINFOHEADER and RGBQUAD array into the file. 
    if (!WriteFile(hf, (LPVOID) pbih, sizeof(BITMAPINFOHEADER) 
       + pbih->biClrUsed * sizeof (RGBQUAD), 
       (LPDWORD) &dwTmp, NULL)) 
     return 0; 

    // Copy the array of color indices into the .BMP file. 
    dwTotal = cb = pbih->biSizeImage; 
    hp = lpBits; 
    if (!WriteFile(hf, (LPSTR) hp, (int) cb, (LPDWORD) &dwTmp, NULL)) return 0; 

    // Close the .BMP file. 
    if (!CloseHandle(hf)) return 0; 

    // Free memory. 
    GlobalFree((HGLOBAL)lpBits); 
    ReleaseDC(0, hdcScr); 
    ReleaseDC(0, hdcMem); 

    return 1; 
} 

Answer 2

你去那里，win32的GDI：

http://www.eggheadcafe.com/software/aspnet/32040380/screenshot-of-a-region-to-a-bmp.aspx

或者你可以直接去MSDN：

http://msdn.microsoft.com/en-us/library/dd183402(v=VS.85).aspx