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   <TITLE>Selecting multiple files in File Open dialog</TITLE>
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<FONT COLOR="#AOAO99">Selecting multiple files in File Open dialog</FONT></H3></CENTER>
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<p>This code was contributed by <a href="mailto:kg@it-gmbh.de">Klaus G黷ter</a>. </p>

<p>Many professional MDI applications support selecting more than one file in the 
File Open dialog. It is easy to add this support to MFC applications.</p>

<p>Opening files (and other document mamangement activities) is implemented in MFC's CDocMananger
class (see source file docmgr.cpp). 
CWinApp contains a member variable m_pDocManager poining to the CDocManager object
to use. If you want to modify the standard MFC behaviour, simply provide your own CDocManager-derived
object.</p>

<p>For adding the "multi open" support, I derived a class CMultiOpenDocManager from CDocManager and
overrode the OnFileOpen function. A new DoPromptFileNames function is a utility function similar to the existing DoPromptFileName function
but capable of returning more than one file name.</p>

<pre><font color="#990000"><tt>class CMultiOpenDocManager : public CDocManager
{
public:
	CMultiOpenDocManager() { }
	virtual void OnFileOpen();
	virtual BOOL DoPromptFileNames(CStringList& fileNames, UINT nIDSTitle, DWORD lFlags, BOOL bOpenFileDialog, CDocTemplate* pTemplate);
};
</tt></font></pre>

<p>Using the feature is as simple as adding the following line in your app's InitInstance function:</p>

<pre><font color="#990000"><tt>	m_pDocManager = new CMultiOpenDocManager;</tt></font></pre>

<p>The implementation of the OnFileOpen function is very similar to the original implementation. I just replaced the call to
DoPromptFileName with a call to my new function DoPromptFileNames, added the OFN_ALLOWMULTISELECT flag
and introduced a loop around the OpenDocumentFile call:</p>

<pre><font color="#990000"><tt>void CMultiOpenDocManager::OnFileOpen()
{
	CStringList newNames;
	if (!DoPromptFileNames(newNames, AFX_IDS_OPENFILE,
	  OFN_HIDEREADONLY | OFN_FILEMUSTEXIST | OFN_ALLOWMULTISELECT, TRUE, NULL))
		return; // open cancelled

	POSITION pos = newNames.GetHeadPosition();
	while (pos)
	{
		CString newName = newNames.GetNext(pos);
		AfxGetApp()->OpenDocumentFile(newName);
	}
}</tt></font></pre>

<p>Now for the DoPromptFileNames function: It is a nearly perfect copy of the original function. 
I marked the modifications by a comment. The implementation uses a function AppendFilterSuffix which
is defines as a file local (static) function in docmgr.cpp. You will have to copy the function
into the file where CMultiOpenDocManager::DoPromptFileNames is implemented.</p>

<pre><font color="#990000"><tt>BOOL CMultiOpenDocManager::DoPromptFileNames(CStringList& fileNames, UINT nIDSTitle, DWORD lFlags, BOOL bOpenFileDialog, CDocTemplate* pTemplate)
{
	CFileDialog dlgFile(bOpenFileDialog);

	CString title;
	VERIFY(title.LoadString(nIDSTitle));

	dlgFile.m_ofn.Flags |= lFlags;

	CString strFilter;
	CString strDefault;
	if (pTemplate != NULL)
	{
		ASSERT_VALID(pTemplate);
		AppendFilterSuffix(strFilter, dlgFile.m_ofn, pTemplate, &strDefault);
	}
	else
	{
		// do for all doc template
		POSITION pos = m_templateList.GetHeadPosition();
		BOOL bFirst = TRUE;
		while (pos != NULL)
		{
			CDocTemplate* pTemplate = (CDocTemplate*)m_templateList.GetNext(pos);
			AppendFilterSuffix(strFilter, dlgFile.m_ofn, pTemplate,
				bFirst ? &strDefault : NULL);
			bFirst = FALSE;
		}
	}

	// append the "*.*" all files filter
	CString allFilter;
	VERIFY(allFilter.LoadString(AFX_IDS_ALLFILTER));
	strFilter += allFilter;
	strFilter += (TCHAR)'\0';   // next string please
#ifndef _MAC
	strFilter += _T("*.*");
#else
	strFilter += _T("****");
#endif
	strFilter += (TCHAR)'\0';   // last string
	dlgFile.m_ofn.nMaxCustFilter++;

	dlgFile.m_ofn.lpstrFilter = strFilter;
#ifndef _MAC
	dlgFile.m_ofn.lpstrTitle = title;
#else
	dlgFile.m_ofn.lpstrPrompt = title;
#endif
	// --- Begin modifications ---
	// - use a big buffer for the file names 
	// (note that pre-SP2 versions of NT 4.0 will nevertheless
	// truncate the result)
	CString strFileNames;
	dlgFile.m_ofn.lpstrFile = strFileNames.GetBuffer(2048);
	dlgFile.m_ofn.nMaxFile = 2048;

	BOOL bResult = dlgFile.DoModal() == IDOK ? TRUE : FALSE;
	strFileNames.ReleaseBuffer();

	if (!bResult)
		return FALSE; // open cancelled

	// - copy the file names to a string list
	POSITION pos = dlgFile.GetStartPosition();
	while (pos)
	{
		fileNames.AddTail(dlgFile.GetNextPathName(pos));
	}
	return TRUE;
	// --- End modifications ---
}</tt></font></pre>




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