Full screenshot to BMP. Issue with bliting and saving

问题

I want to take a capture of part of screen and save it into BMP. To save picture I plan with SOIL. Bit bliting functions I get here.

Code:

bool saveScreen(string path)
{
    string name;
    SYSTEMTIME sm;
    GetSystemTime(&sm);
    name = to_string(sm.wHour) + to_string(sm.wMinute) + to_string(sm.wSecond) + to_string(sm.wMilliseconds) 
    + "_" + to_string(sm.wDay) + to_string(sm.wMonth) + to_string(sm.wYear);

    path = /*path + "/" +*/ name + ".bmp";
    const char *charPath = path.c_str();

    BITMAPINFO bmi;
    auto& hdr = bmi.bmiHeader;
    hdr.biSize = sizeof(bmi.bmiHeader);
    hdr.biWidth = screenWidth;
    hdr.biHeight = screenHeight;
    hdr.biPlanes = 1;
    hdr.biBitCount = 32;
    hdr.biCompression = BI_RGB;
    hdr.biSizeImage = 0;
    hdr.biXPelsPerMeter = 0;
    hdr.biYPelsPerMeter = 0;
    hdr.biClrUsed = 0;
    hdr.biClrImportant = 0;

    unsigned char* bitmapBits;
    HDC hdc = GetDC(NULL);
    HDC hBmpDc = CreateCompatibleDC(hdc);

    BITMAP bm;
    HBITMAP hBmp = CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, (void**)&bitmapBits, nullptr, 0);
    SelectObject(hBmpDc, hBmp);
    BitBlt(hBmpDc, 0, 0, screenWidth, 1024, hdc, 0, 0, SRCCOPY);

    vector< unsigned char > buf(screenWidth* screenHeight* 3);

    glPixelStorei(GL_PACK_ALIGNMENT, 1);
    glReadPixels(0, 0, screenWidth, screenHeight, GL_RGB, GL_UNSIGNED_BYTE, bitmapBits);

    int texture = SOIL_save_image(charPath, SOIL_SAVE_TYPE_BMP, screenWidth, screenHeight, 3, bitmapBits);

    return texture;
}

On output I get this:

Broken BMP

It looks as RGBA/RGB issue, but I don't set RGBA nowhere. What I missed in the code? It's the right way to get screenshot?

回答1:

You create 32 bpp image, however pass 3 to SOIL_save_image indicating that it is 24 bpp image.

来源：https://stackoverflow.com/questions/44204732/full-screenshot-to-bmp-issue-with-bliting-and-saving