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NULL parameter to DSM_Entry

Forums › TWAIN Classic › NULL parameter to DSM_Entry

  • This topic has 0 replies, 1 voice, and was last updated 14 years, 8 months ago by anjin.
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  • May 9, 2006 at 2:35 am #21940 Reply
    anjin
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    Hi! I’m using TWAIN (with Visual C++ on Visual Studio 2005) to interface with a scanner. The function DSM_Entry is accessed via a loaded DLL, TWAIN_32.DLL:

    m_hTwain = LoadLibrary(_T(“TWAIN_32.DLL”));
    m_DSMEntryProc = (DSMENTRYPROC)GetProcAddress(m_hTwain, (LPCSTR)MAKEINTRESOURCE(1));

    I then call the procedure using:

    TW_UINT16 nRes =(*m_DSMEntryProc)(&m_appID, pDest, dg, dat, msg, pData);

    however, some calls need for pDest to be null, (like the triplet DG_CONTROL / DAT_IDENTITY / MSG_USERSELECT for those who know TWAIN).

    Unfortunately,when pDest is null for this call, an access violation appears. For other triplets, the call is OK. Has anyone encountered this before? Am I passing “NULL” the wrong way?

    Thanks!

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