Why JPG display only with 16 color in Dialog?

From:

ckkwan@my-deja.com

Newsgroups:

microsoft.public.vc.mfc

Date:

19 Aug 2006 03:30:45 -0700

Message-ID:

<1155983445.451222.78450@h48g2000cwc.googlegroups.com>

Any clue? The code is attached below.

TIA.

void CCardDlg::LoadAndDisplayJpeg()
{
    long Len;
    CFile File;
    HGLOBAL hglob = NULL;
    HBITMAP hbm = NULL;
    CPaintDC dc(this);

    try
    {
        File.Open(_T("\\tmp\\YanYan.jpg"), CFile::modeRead);

        Len = File.GetLength();

        hglob = GlobalAlloc(GMEM_MOVEABLE, Len + 1);
        if (hglob == NULL) CGException::ThrowLastError();
        try
        {
            File.Read(GlobalLock(hglob), Len);
        }
        catch(...)
        {
            GlobalUnlock(hglob);
            throw;
        }
        GlobalUnlock(hglob);

        hbm = LoadJpeg(hglob);

        // Draw the Bitmap
        CDC mdc;
        CRect rect;
        CBitmap *Bmp;
        BITMAP bmp;

        mdc.CreateCompatibleDC(NULL);
        Bmp = CBitmap::FromHandle(hbm);
        CBitmap *obmp = mdc.SelectObject(Bmp);

        GetClientRect(&rect);
        Bmp->GetBitmap(&bmp);
        dc.StretchBlt(0, 0, rect.Width(), rect.Height(),
            &mdc, 0, 0, bmp.bmWidth, bmp.bmHeight, SRCCOPY);

        mdc.SelectObject(obmp);

        m_Photo.DeleteObject();
        m_Photo.CreateBitmapIndirect(&bmp);

        // Free resource
        GlobalFree(hglob);
        hglob = NULL;
        DeleteObject(hbm);
        hbm = NULL;

        GetDlgItem(IDC_SC_PHOTO)->Invalidate();
    }
    catch(...)
    {
        if (hglob != NULL) GlobalFree(hglob);
        if (hbm != NULL) DeleteObject(hbm);
        throw;
    }
}

HBITMAP CCardDlg::LoadJpeg(HGLOBAL hglob) const
{
    IStream *stream = NULL;
    CreateStreamOnHGlobal(hglob, FALSE, &stream);
    IPicture *pic;
    OleLoadPicture(stream, 0, FALSE, IID_IPicture, (void**) &pic);
    stream->Release();
    HBITMAP hbm0 = NULL;
    pic->get_Handle((OLE_HANDLE*) &hbm0);

    // Now we make a copy of it into our own hbm
    DIBSECTION dibs;
    ::GetObject(hbm0, sizeof(dibs), &dibs);
// if (dibs.dsBm.bmBitsPixel != 24)
// {
// pic->Release();
// return NULL;
// }
    int w = dibs.dsBm.bmWidth, h = dibs.dsBm.bmHeight;
    dibs.dsBmih.biClrUsed = 0;
    dibs.dsBmih.biClrImportant = 0;
    void *bits;
    HDC sdc = ::GetDC(m_hWnd);
    HBITMAP hbm1 = ::CreateDIBSection(sdc, (BITMAPINFO*) &dibs.dsBmih,
DIB_RGB_COLORS, &bits, 0, 0);
    //
    HDC hdc0 = ::CreateCompatibleDC(sdc);
    HDC hdc1 = ::CreateCompatibleDC(sdc);
    HGDIOBJ hold0 = ::SelectObject(hdc0, hbm0);
    HGDIOBJ hold1 = ::SelectObject(hdc1, hbm1);
    ::BitBlt(hdc1, 0, 0, w, h, hdc0, 0, 0, SRCCOPY);
    ::SelectObject(hdc0, hold0);
    ::SelectObject(hdc1, hold1);
    ::DeleteDC(hdc0);
    ::DeleteDC(hdc1);
    ::ReleaseDC(m_hWnd, sdc);
    pic->Release();
    return hbm1;
}