在我告诉大家怎么样修改MFC浏览程序中文件读写对话框的缺省设置之前呢，我们应该先知道MFC是怎么样显示文件打开和文件保存对话框的。如果你选择了文件菜单中的打开，那么就会有一个消息发送给CWinApp::OnFileOpen，通过一个成员变量m_pDocManager(一个指向CDocManager 对象的指针)来调用CDocManager::OnFileOpen，那么函数就会调用CDocManager的虚函数DoPromptFileName，成功后再调用CWinApp::OpenDocumentFile函数，这个文件对话框就是在DoPromptFileName的虚函数中显示的。当我们打开的是保存对话框时，文件保存(或另存为)命令消息就会发给CDocument::OnFileSave (or CDocument::OnFileSaveAs)，在这2种情况下，CDocument::DoSave函数都会被调用。最后，如果文件名是空的，那么CDocument::DoSave就会调用CWinApp::DoPromptFileName，使得成员变量m_pDocManager有效，并且调用CDocManager::DoPromptFileName来显示保存对话框。
那么现在大家都明白了，CDocManager::DoPromptFileName函数(注意它是一个虚函数)就是负责显示标准的文件打开和保存对话框的(可是有一个BOOL变量来决定显示哪一个对话框的)。
现在看起来，这好象对改变默认的对话框设置没什么用。你可能也没有考虑过在类CDocManager中的DoPromptFileName函数，或者不知道怎么改，来使用你自己的CDocManager类。那么你不用急，下面的代码就是告诉你怎么自定义CDocManager。
// CDocManager class declaration
//
class CDocManagerEx : public CDocManager
{
DECLARE_DYNAMIC(CDocManagerEx)
// Construction
public:
CDocManagerEx();
// Attributes
public:
// Operations
public:
// Overrides
// helper for standard commdlg dialogs
virtual BOOL DoPromptFileName(CString& fileName, UINT nIDSTitle,
DWORD lFlags, BOOL bOpenFileDialog, CDocTemplate* pTemplate);
// Implementation
public:
virtual ~CDocManagerEx();
};
// DocManager.cpp : implementation file
//
#include "stdafx.h"
#include "PreviewFileDlg.h"
#include "DocManager.h" // the header with the class declaration
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
static void AppendFilterSuffix(CString& filter, OPENFILENAME& ofn,
CDocTemplate* pTemplate, CString* pstrDefaultExt)
{
ASSERT_VALID(pTemplate);
ASSERT_KINDOF(CDocTemplate, pTemplate);
CString strFilterExt, strFilterName;
if (pTemplate->GetDocString(strFilterExt, CDocTemplate::filterExt) &&
!strFilterExt.IsEmpty() &&
pTemplate->GetDocString(strFilterName, CDocTemplate::filterName) &&
!strFilterName.IsEmpty())
{
// a file based document template - add to filter list
#ifndef _MAC
ASSERT(strFilterExt[0] == '.');
#endif
if (pstrDefaultExt != NULL)
{
// set the default extension
#ifndef _MAC
*pstrDefaultExt = ((LPCTSTR)strFilterExt) 1; // skip the '.'
#else
*pstrDefaultExt = strFilterExt;
#endif
ofn.lpstrDefExt = (LPTSTR)(LPCTSTR)(*pstrDefaultExt);
ofn.nFilterIndex = ofn.nMaxCustFilter 1; // 1 based number
}
// add to filter
filter = strFilterName;
ASSERT(!filter.IsEmpty()); // must have a file type name
filter = (TCHAR)'\0'; // next string please
#ifndef _MAC
filter = (TCHAR)'*';
#endif
filter = strFilterExt;
filter = (TCHAR)'\0'; // next string please
ofn.nMaxCustFilter ;
}
}
/////////////////////////////////////////////////////////////////////////////
// CDocManagerEx
IMPLEMENT_DYNAMIC(CDocManagerEx, CDocManager)
CDocManagerEx::CDocManagerEx()
{
}
CDocManagerEx::~CDocManagerEx()
{
}
BOOL CDocManagerEx::DoPromptFileName(CString& fileName, UINT nIDSTitle, DWORD lFlags, BOOL bOpenFileDialog, CDocTemplate* pTemplate)
{
CPreviewFileDlg dlgFile(bOpenFileDialog); // this is the only modified line!
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
dlgFile.m_ofn.lpstrFile = fileName.GetBuffer(_MAX_PATH);
BOOL bResult = dlgFile.DoModal() == IDOK ? TRUE : FALSE;
fileName.ReleaseBuffer();
return bResult;
}
以上代码是从MFC原代码中完整的拷贝过来的，当中只有一行需要改：对话框的声明(当然，由于这是CFileDialog的子类，你可以有更多的修改权)，而且对于标准对话框来说，还应该有预览功能。AppendFilterSuffix函数是从DoPromptFileName中被调用的，原代码可以从你的工程中获得。如果你想显示打开和保存对话框，你可以使用bOpenFileDialog参数，TRUE表示对话框是打开对话框，反之，亦然。
当然我们也可以使用我们自己定义的CDocManagerEx类来代替原来的CDocManager类，CWinApp是通过成员变量m_pDocManager来使用文档管理器，所以我们必须正确的初始化这个变量。有必要特别关注一下在CWinApp::AddDocTemplate中CWinApp创建对象的原代码，这其中有一个很普通的函数调用，我们把它给忽略了，那就是CWinApp::InitInstance函数。当m_pDocManager参数是NULL的时候，CWinApp::AddDocTemplate函数只是创建CDocManager对象，那么一旦m_pDocManager指针被正确的初始化，CWinApp::AddDocTemplate函数也就能够被正确的调用了。因此，这最后一步就是在调用CWinApp::AddDocTemplate之前就初始化成员变量m_pDocManager，以达到我们想要的样子。(当然你也不一定得调用CWinApp::AddDocTemplate，而是直接调用m_pDocManager->AddDocTemplate也行)
以下就是代码：
BOOL COurApp::InitInstance()
{
// Standard initialization
// If you are not using these features and wish to reduce the size
// of your final executable, you should remove from the following
// the specific initialization routines you do not need.
#ifdef _AFXDLL
Enable3dControls(); // Call this when using MFC in a shared DLL
#else
Enable3dControlsStatic(); // Call this when linking to MFC statically
#endif
// Change the registry key under which our settings are stored.
// You should modify this string to be something appropriate
// such as the name of your company or organization.
SetRegistryKey(_T("Local AppWizard-Generated Applications"));
LoadStdProfileSettings(); // Load standard INI file options (including MRU)
// Register the application's document templates. Document templates
// serve as the connection between documents, frame windows and views.
CMultiDocTemplate* pDocTemplate;
pDocTemplate = new CMultiDocTemplate(
IDR_DIBTYPE,
RUNTIME_CLASS(COurDoc),
RUNTIME_CLASS(CChildFrame), // custom MDI child frame
RUNTIME_CLASS(COurView));
ASSERT(m_pDocManager == NULL);
m_pDocManager = new CDocManagerEx;
m_pDocManager->AddDocTemplate(pDocTemplate); // or just AddDocTemplate(pDocTemplate);
// create main MDI Frame window
CMainFrame* pMainFrame = new CMainFrame;
if (!pMainFrame->LoadFrame(IDR_MAINFRAME))
return FALSE;
m_pMainWnd = pMainFrame;
// Enable drag/drop open
m_pMainWnd->DragAcceptFiles();
// Enable DDE Execute open
EnableShellOpen();
RegisterShellFileTypes(TRUE);
// Parse command line for standard shell commands, DDE, file open
CCommandLineInfo cmdInfo;
ParseCommandLine(cmdInfo);
// Dispatch commands specified on the command line
if (!ProcessShellCommand(cmdInfo))
return FALSE;
// The main window has been initialized, so show and update it.
pMainFrame->ShowWindow(m_nCmdShow);
pMainFrame->UpdateWindow();
return TRUE;
}
from: http://www.quickviews.net/data/2006/0421/article_16587_1.htm