Re: REALLockPictureDescription on Win32

[Alfred Van Hoek <vanhoek at mac dot com>]

on 5/30/04 9:00 PM, Brad Hutchings at brad at componentx dot com wrote:

> this code snippet:
> 
> #if CX_GRAPHICS_WIN32
> BITMAPINFO bmi;
> bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
> bmi.bmiHeader.biWidth = width;
> bmi.bmiHeader.biHeight = height;
> bmi.bmiHeader.biPlanes = 1;
> bmi.bmiHeader.biBitCount = depth;
> bmi.bmiHeader.biCompression = BI_RGB;
> bmi.bmiHeader.biSizeImage =
> ((bmi.bmiHeader.biWidth*bmi.bmiHeader.biBitCount/
> 8+3)&0xFFFFFFFC)*bmi.bmiHeader.biHeight;
> bmi.bmiHeader.biXPelsPerMeter = 2835;        //    72 dpi
> bmi.bmiHeader.biYPelsPerMeter = 2835;        //    72 dpi
> bmi.bmiHeader.biClrUsed = 0;
> bmi.bmiHeader.biClrImportant = 0;
> 
> HDC    dc = CreateCompatibleDC(NULL);
> debug_message("created dc");
> 
> void* bits;
> HBITMAP hbm = CreateDIBSection(dc, &bmi, DIB_RGB_COLORS, &bits, 0, 0);
> debug_message("created dib");
> 
> _fPicture = REALBuildPictureFromDIB(hbm, true);
> debug_message("created _fPicture");
> ...


COuld be a memset problem, you don't use, or a selectObject or ...

Here are code snippets that work for me (did not try to create a picture of
it, but drawing in the memoryDC is ok:

HDC    _CreateMemoryDC(HWND hwnd)
{
    HDC    hMemDC, hDC;

    hDC = GetDC(hwnd);
    if (hDC) {
        hMemDC = CreateCompatibleDC(hDC);
        SetMapMode(hMemDC, GetMapMode(hDC));
        ReleaseDC(hwnd, hDC);
        return hMemDC;
    }
    return NULL;
}

WORD _GetDCBitDepth(HDC hDC)
{
    return(GetDeviceCaps( hDC, BITSPIXEL));
}



    // a struct large enough to hold the largest bitmapinfo ...
    struct BITMAPINFO_256 {
        BITMAPINFOHEADER bmiHeader;
        long bmiColors[256];
    };
    typedef struct BITMAPINFO_256 BITMAPINFO_256;

    BITMAPINFO_256 bitmapInfo;

    void *baseaddr;

    // create a DIB section
    memset(&bitmapInfo, 0, sizeof(bitmapInfo));

    bitmapInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bitmapInfo.bmiHeader.biWidth = width;
    bitmapInfo.bmiHeader.biHeight =  -1 * height;    // top down dib
    bitmapInfo.bmiHeader.biPlanes = 1;
    bitmapInfo.bmiHeader.biBitCount = depth;
    bitmapInfo.bmiHeader.biCompression = BI_RGB;
    bitmapInfo.bmiHeader.biSizeImage = 0;
    bitmapInfo.bmiHeader.biXPelsPerMeter = 0;
    bitmapInfo.bmiHeader.biYPelsPerMeter = 0;
    bitmapInfo.bmiHeader.biClrUsed = 0;
    bitmapInfo.bmiHeader.biClrImportant = 0;
    bitmapInfo.bmiColors[0] = 0;
    bitmapInfo.bmiColors[1] = 0;
    bitmapInfo.bmiColors[2] = 0;
    bitmapInfo.bmiColors[3] = 0;



    data->hBitmap = CreateDIBSection(hDC, (BITMAPINFO *)&bitmapInfo,
DIB_RGB_COLORS, &baseaddr, nil, 0);
    SelectObject(data->hMemDC, data->hBitmap);

    ReleaseDC(owner, hDC);


HTH,

Alfred

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