Re: How to select a lot of files

From:
"Giovanni Dicanio" <giovanni.dicanio@invalid.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Wed, 18 Jun 2008 09:41:08 +0200
Message-ID:
<Oe5ZFcR0IHA.2068@TK2MSFTNGP05.phx.gbl>
"Drew" <dam@dam.com> ha scritto nel messaggio
news:u5tE23L0IHA.2084@TK2MSFTNGP06.phx.gbl...

I'm using OFN_ALLOWMULTISELECT as a CFileDialog style and I am having the
problem that when I select above a certain number of files my DoModal()
call returns IDCANCEL.


Hi,

I found an old post I wrote in this newsgroup, with a sample code that may
interest you:

 [subject] CFileDialog failure
 [date] 2007, October 19th

<code>

//------------------------------------------------------------------
// Given the file list from Open file dialog in multi-select mode,
// parses it and prints its content to the user.
//------------------------------------------------------------------
void CTestDlg::ProcessFileList( LPCTSTR fileList )
{
    ASSERT( fileList != NULL );

    //
    // Parse file list from CFileDialog,
    // and build a string list from it
    //
    LPCTSTR pstr = fileList;
    std::vector< CString > strings;
    while ( true )
    {
        if ( *pstr == _T('\0') && *(pstr+1) == _T('\0') )
        {
            break;
        }

        // Ciao 0
        // 1234 5
        // *
        // 0123 4
        strings.push_back( CString(pstr) );
        pstr += (_tcslen(pstr) + 1);
    }

    //
    // Build a message with the file names
    //
    CString msg;
    msg = _T("*** Selected files ***\n\n");
    msg += _T("Path : ") + strings.at(0); // First string is path name
    msg += _T("\n\n");
    for ( size_t i = 1; i < strings.size(); i++ )
    {
        msg += strings.at(i);
        msg += _T("\n");
    }
    AfxMessageBox( msg );

}

//------------------------------------------------------------------
// Tests Open file dialog in multi-select mode.
//------------------------------------------------------------------
void CTestDlg::OnBnClickedButton1()
{
    // Max files in list (including folder path)
    const int MaxFileCount = 50;

    // Max TCHARs per file
    const int MaxFilePath = MAX_PATH;

    // Calculate approx size for the given number of max files.
    // The "+1" is for the terminating NUL (_T('\0')) character.
    const int MaxFileBuffer = MaxFileCount * MaxFilePath + 1;
// const int MaxFileBuffer = 30; // TEST for small buffer

    // Buffer for file names
    std::vector< TCHAR > fileNamesBuffer(MaxFileBuffer);

    // File dialog object, dynamically allocated
    // at each loop iteration
    CFileDialog * fileDlg = NULL;
    while ( true )
    {
        // Allocate a new file dialog object
        ASSERT( fileDlg == NULL );
        fileDlg = new CFileDialog(
            TRUE, // Open file dialog
            NULL, // No default extension
            NULL, // Initial file name
            OFN_HIDEREADONLY | OFN_ALLOWMULTISELECT,
            _T("All files (*.*)|*.*||"), // Filter
            this // Parent
        );

        // Hook our buffer to file dialog structure
        fileDlg->GetOFN().lpstrFile = &(fileNamesBuffer[0]);
        fileDlg->GetOFN().nMaxFile = (DWORD) fileNamesBuffer.size();

        // Clear buffer content, so we don't see garbage
        // from the previous iteration
        // (if the previous iteration failed).
        ::ZeroMemory( &(fileNamesBuffer[0]),
            fileNamesBuffer.size() * sizeof(TCHAR) );

        // Run the dialog-box
        INT_PTR result = fileDlg->DoModal();

        // Avoid memory leaks
        delete fileDlg;
        fileDlg = NULL;

        // Check result
        if ( result == IDCANCEL )
        {
            // Failure or user pressed Cancel?
            DWORD dw = ::CommDlgExtendedError();
            if ( dw & FNERR_BUFFERTOOSMALL )
            {
                // Failure due to few buffer memory;
                // tell that to the user
                AfxMessageBox( _T("Too many files selected.") );

                // Do another iteration
                continue;
            }

            // User pressed cancel, or other error.
            // Quit loop.
            break;
        }

        // User pressed OK:
        // Show selected files and quit loop.
        ProcessFileList( &(fileNamesBuffer[0]) );
        break;
    }

}

</code>

HTH,
Giovanni

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