MFC OnFileNew OnFileOpen过程分析代码（以记录MFC学习点滴）

对OnFileNew()/OnFileOpen()的MFC代码跟踪简析，简析可能也谈不上了，为了快速的理解MFC的实现思路以及文档视图架构的应用，在学习的过程当中我也没有进行学习理解的注解。不过细细阅读整个的实现流程，相信你我都能理解掌握MFC的整体思路。以后有机会再进行注解吧。

A) OnFileNew()执行过程分析

1. void CWinApp::OnFileNew()

{
if (m_pDocManager != NULL)
m_pDocManager->OnFileNew();
}
注释:MFC对ID_FILE_NEW菜单的响应函数,系统默认操作.

2. void CDocManager::OnFileNew()

{
if (m_templateList.IsEmpty())
{
TRACE0("Error: no document templates registered with CWinApp./n");
AfxMessageBox(AFX_IDP_FAILED_TO_CREATE_DOC);
return;
}

CDocTemplate* pTemplate = (CDocTemplate*)m_templateList.GetHead();
if (m_templateList.GetCount() > 1)
{
// more than one document template to choose from
// bring up dialog prompting user
CNewTypeDlg dlg(&m_templateList);
int nID = dlg.DoModal();
if (nID == IDOK)
pTemplate = dlg.m_pSelectedTemplate;
else
return; // none - cancel operation
}

ASSERT(pTemplate != NULL);
ASSERT_KINDOF(CDocTemplate, pTemplate);

pTemplate->OpenDocumentFile(NULL);
// if returns NULL, the user has already been alerted
}
注:如果跳过此函数而手动操作直接进入pTemplate->OpenDocumentFile(),那么文档模版列表选择对话框也就不会出现了.

3. CDocument* CMultiDocTemplate::OpenDocumentFile(LPCTSTR lpszPathName,BOOL bMakeVisible)

{
CDocument* pDocument = CreateNewDocument();
if (pDocument == NULL)
{
TRACE0("CDocTemplate::CreateNewDocument returned NULL./n");
AfxMessageBox(AFX_IDP_FAILED_TO_CREATE_DOC);
return NULL;
}
ASSERT_VALID(pDocument);

BOOL bAutoDelete = pDocument->m_bAutoDelete;
pDocument->m_bAutoDelete = FALSE; // don't destroy if something goes wrong
CFrameWnd* pFrame = CreateNewFrame(pDocument, NULL);
pDocument->m_bAutoDelete = bAutoDelete;
if (pFrame == NULL)
{
AfxMessageBox(AFX_IDP_FAILED_TO_CREATE_DOC);
delete pDocument; // explicit delete on error
return NULL;
}
ASSERT_VALID(pFrame);

if (lpszPathName == NULL)
{
// create a new document - with default document name
SetDefaultTitle(pDocument);

// avoid creating temporary compound file when starting up invisible
if (!bMakeVisible)
pDocument->m_bEmbedded = TRUE;

if (!pDocument->OnNewDocument())
{
// user has be alerted to what failed in OnNewDocument
TRACE0("CDocument::OnNewDocument returned FALSE./n");
pFrame->DestroyWindow();
return NULL;
}

// it worked, now bump untitled count
m_nUntitledCount++;
}
else
{
// open an existing document
CWaitCursor wait;
if (!pDocument->OnOpenDocument(lpszPathName))
{
// user has be alerted to what failed in OnOpenDocument
TRACE0("CDocument::OnOpenDocument returned FALSE./n");
pFrame->DestroyWindow();
return NULL;
}
pDocument->SetPathName(lpszPathName);
}

InitialUpdateFrame(pFrame, pDocument, bMakeVisible);
return pDocument;
}

4. CDocument* CDocTemplate::CreateNewDocument()

{
// default implementation constructs one from CRuntimeClass
if (m_pDocClass == NULL)
{
TRACE0("Error: you must override CDocTemplate::CreateNewDocument./n");
ASSERT(FALSE);
return NULL;
}
CDocument* pDocument = (CDocument*)m_pDocClass->CreateObject();
if (pDocument == NULL)
{
TRACE1("Warning: Dynamic create of document type %hs failed./n",
m_pDocClass->m_lpszClassName);
return NULL;
}
ASSERT_KINDOF(CDocument, pDocument);
AddDocument(pDocument);
return pDocument;
}

5. CFrameWnd* CDocTemplate::CreateNewFrame(CDocument* pDoc, CFrameWnd* pOther)

{
if (pDoc != NULL)
ASSERT_VALID(pDoc);
// create a frame wired to the specified document

ASSERT(m_nIDResource != 0); // must have a resource ID to load from
CCreateContext context;
context.m_pCurrentFrame = pOther;
context.m_pCurrentDoc = pDoc;
context.m_pNewViewClass = m_pViewClass;
context.m_pNewDocTemplate = this;

if (m_pFrameClass == NULL)
{
TRACE0("Error: you must override CDocTemplate::CreateNewFrame./n");
ASSERT(FALSE);
return NULL;
}
CFrameWnd* pFrame = (CFrameWnd*)m_pFrameClass->CreateObject();
if (pFrame == NULL)
{
TRACE1("Warning: Dynamic create of frame %hs failed./n",
m_pFrameClass->m_lpszClassName);
return NULL;
}
ASSERT_KINDOF(CFrameWnd, pFrame);

if (context.m_pNewViewClass == NULL)
TRACE0("Warning: creating frame with no default view./n");

// create new from resource
if (!pFrame->LoadFrame(m_nIDResource,
WS_OVERLAPPEDWINDOW | FWS_ADDTOTITLE, // default frame styles
NULL, &context))
{
TRACE0("Warning: CDocTemplate couldn't create a frame./n");
// frame will be deleted in PostNcDestroy cleanup
return NULL;
}

// it worked !
return pFrame;
}

6. BOOL CDocument::OnNewDocument()

{
if (IsModified())
TRACE0("Warning: OnNewDocument replaces an unsaved document./n");

DeleteContents();
m_strPathName.Empty(); // no path name yet
SetModifiedFlag(FALSE); // make clean

return TRUE;
}

7. BOOL CDocument::OnOpenDocument(LPCTSTR lpszPathName)

{
if (IsModified())
TRACE0("Warning: OnOpenDocument replaces an unsaved document./n");

CFileException fe;
CFile* pFile = GetFile(lpszPathName,
CFile::modeRead|CFile::shareDenyWrite, &fe);
if (pFile == NULL)
{
ReportSaveLoadException(lpszPathName, &fe,
FALSE, AFX_IDP_FAILED_TO_OPEN_DOC);
return FALSE;
}

DeleteContents();
SetModifiedFlag(); // dirty during de-serialize

CArchive loadArchive(pFile, CArchive::load | CArchive::bNoFlushOnDelete);
loadArchive.m_pDocument = this;
loadArchive.m_bForceFlat = FALSE;
TRY
{
CWaitCursor wait;
if (pFile->GetLength() != 0)
Serialize(loadArchive); // load me
loadArchive.Close();
ReleaseFile(pFile, FALSE);
}
CATCH_ALL(e)
{
ReleaseFile(pFile, TRUE);
DeleteContents(); // remove failed contents

TRY
{
ReportSaveLoadException(lpszPathName, e,
FALSE, AFX_IDP_FAILED_TO_OPEN_DOC);
}
END_TRY
DELETE_EXCEPTION(e);
return FALSE;
}
END_CATCH_ALL

SetModifiedFlag(FALSE); // start off with unmodified

return TRUE;
}

8. BOOL CFrameWnd::LoadFrame(UINT nIDResource, DWORD dwDefaultStyle, CWnd* pParentWnd, CCreateContext* pContext)

{
// only do this once
ASSERT_VALID_IDR(nIDResource);
ASSERT(m_nIDHelp == 0 || m_nIDHelp == nIDResource);

m_nIDHelp = nIDResource; // ID for help context (+HID_BASE_RESOURCE)

CString strFullString;
if (strFullString.LoadString(nIDResource))
AfxExtractSubString(m_strTitle, strFullString, 0); // first sub-string

VERIFY(AfxDeferRegisterClass(AFX_WNDFRAMEORVIEW_REG));

// attempt to create the window
LPCTSTR lpszClass = GetIconWndClass(dwDefaultStyle, nIDResource);
LPCTSTR lpszTitle = m_strTitle;
if (!Create(lpszClass, lpszTitle, dwDefaultStyle, rectDefault,
pParentWnd, MAKEINTRESOURCE(nIDResource), 0L, pContext))
{
return FALSE; // will self destruct on failure normally
}

// save the default menu handle
ASSERT(m_hWnd != NULL);
m_hMenuDefault = ::GetMenu(m_hWnd);

// load accelerator resource
LoadAccelTable(MAKEINTRESOURCE(nIDResource));

if (pContext == NULL) // send initial update
SendMessageToDescendants(WM_INITIALUPDATE, 0, 0, TRUE, TRUE);

return TRUE;
}

9. void DocTemplate::InitialUpdateFrame(CFrameWnd* pFrame, CDocument* pDoc,BOOL bMakeVisible)

{
// just delagate to implementation in CFrameWnd
pFrame->InitialUpdateFrame(pDoc, bMakeVisible);
}

10. void CFrameWnd::InitialUpdateFrame(CDocument* pDoc, BOOL bMakeVisible)
{
// if the frame does not have an active view, set to first pane
CView* pView = NULL;
if (GetActiveView() == NULL)
{
CWnd* pWnd = GetDescendantWindow(AFX_IDW_PANE_FIRST, TRUE);
if (pWnd != NULL && pWnd->IsKindOf(RUNTIME_CLASS(CView)))
{
pView = (CView*)pWnd;
SetActiveView(pView, FALSE);
}
}

if (bMakeVisible)
{
// send initial update to all views (and other controls) in the frame
SendMessageToDescendants(WM_INITIALUPDATE, 0, 0, TRUE, TRUE);

// give view a chance to save the focus (CFormView needs this)
if (pView != NULL)
pView->OnActivateFrame(WA_INACTIVE, this);

// finally, activate the frame
// (send the default show command unless the main desktop window)
int nCmdShow = -1; // default
CWinApp* pApp = AfxGetApp();
if (pApp != NULL && pApp->m_pMainWnd == this)
{
nCmdShow = pApp->m_nCmdShow; // use the parameter from WinMain
pApp->m_nCmdShow = -1; // set to default after first time
}
ActivateFrame(nCmdShow);
if (pView != NULL)
pView->OnActivateView(TRUE, pView, pView);
}

// update frame counts and frame title (may already have been visible)
if (pDoc != NULL)
pDoc->UpdateFrameCounts();
OnUpdateFrameTitle(TRUE);
}

B) OnFileOpen()执行过程分析

11. void CWinApp::OnFileOpen()

{
ASSERT(m_pDocManager != NULL);
m_pDocManager->OnFileOpen();
}

12. void CDocManager::OnFileOpen()

{
// prompt the user (with all document templates)
CString newName;
if (!DoPromptFileName(newName, AFX_IDS_OPENFILE,
OFN_HIDEREADONLY | OFN_FILEMUSTEXIST, TRUE, NULL))
return; // open cancelled

AfxGetApp()->OpenDocumentFile(newName);
// if returns NULL, the user has already been alerted
}

13. CDocument* CWinApp::OpenDocumentFile(LPCTSTR lpszFileName)

{
ASSERT(m_pDocManager != NULL);
return m_pDocManager->OpenDocumentFile(lpszFileName);
}

14. CDocument* CDocManager::OpenDocumentFile(LPCTSTR lpszFileName)

{
// find the highest confidence
POSITION pos = m_templateList.GetHeadPosition();
CDocTemplate::Confidence bestMatch = CDocTemplate::noAttempt;
CDocTemplate* pBestTemplate = NULL;
CDocument* pOpenDocument = NULL;

TCHAR szPath[_MAX_PATH];
ASSERT(lstrlen(lpszFileName) < _countof(szPath));
TCHAR szTemp[_MAX_PATH];
if (lpszFileName[0] == '/"')
++lpszFileName;
lstrcpyn(szTemp, lpszFileName, _MAX_PATH);
LPTSTR lpszLast = _tcsrchr(szTemp, '/"');
if (lpszLast != NULL)
*lpszLast = 0;
AfxFullPath(szPath, szTemp);
TCHAR szLinkName[_MAX_PATH];
if (AfxResolveShortcut(AfxGetMainWnd(), szPath, szLinkName, _MAX_PATH))
lstrcpy(szPath, szLinkName);

while (pos != NULL)
{
CDocTemplate* pTemplate = (CDocTemplate*)m_templateList.GetNext(pos);
ASSERT_KINDOF(CDocTemplate, pTemplate);

CDocTemplate::Confidence match;
ASSERT(pOpenDocument == NULL);
match = pTemplate->MatchDocType(szPath, pOpenDocument);
if (match > bestMatch)
{
bestMatch = match;
pBestTemplate = pTemplate;
}
if (match == CDocTemplate::yesAlreadyOpen)
break; // stop here
}

if (pOpenDocument != NULL)
{
POSITION pos = pOpenDocument->GetFirstViewPosition();
if (pos != NULL)
{
CView* pView = pOpenDocument->GetNextView(pos); // get first one
ASSERT_VALID(pView);
CFrameWnd* pFrame = pView->GetParentFrame();
if (pFrame != NULL)
pFrame->ActivateFrame();
else
TRACE0("Error: Can not find a frame for document to activate./n");
CFrameWnd* pAppFrame;
if (pFrame != (pAppFrame = (CFrameWnd*)AfxGetApp()->m_pMainWnd))
{
ASSERT_KINDOF(CFrameWnd, pAppFrame);
pAppFrame->ActivateFrame();
}
}
else
{
TRACE0("Error: Can not find a view for document to activate./n");
}
return pOpenDocument;
}

if (pBestTemplate == NULL)
{
AfxMessageBox(AFX_IDP_FAILED_TO_OPEN_DOC);
return NULL;
}

return pBestTemplate->OpenDocumentFile(szPath);
}

15. CDocument* CMultiDocTemplate::OpenDocumentFile(LPCTSTR lpszPathName,BOOL bMakeVisible)

{
CDocument* pDocument = CreateNewDocument();
if (pDocument == NULL)
{
TRACE0("CDocTemplate::CreateNewDocument returned NULL./n");
AfxMessageBox(AFX_IDP_FAILED_TO_CREATE_DOC);
return NULL;
}
ASSERT_VALID(pDocument);

BOOL bAutoDelete = pDocument->m_bAutoDelete;
pDocument->m_bAutoDelete = FALSE; // don't destroy if something goes wrong
CFrameWnd* pFrame = CreateNewFrame(pDocument, NULL);
pDocument->m_bAutoDelete = bAutoDelete;
if (pFrame == NULL)
{
AfxMessageBox(AFX_IDP_FAILED_TO_CREATE_DOC);
delete pDocument; // explicit delete on error
return NULL;
}
ASSERT_VALID(pFrame);

if (lpszPathName == NULL)
{
// create a new document - with default document name
SetDefaultTitle(pDocument);

// avoid creating temporary compound file when starting up invisible
if (!bMakeVisible)
pDocument->m_bEmbedded = TRUE;

if (!pDocument->OnNewDocument())
{
// user has be alerted to what failed in OnNewDocument
TRACE0("CDocument::OnNewDocument returned FALSE./n");
pFrame->DestroyWindow();
return NULL;
}

// it worked, now bump untitled count
m_nUntitledCount++;
}
else
{
// open an existing document
CWaitCursor wait;
if (!pDocument->OnOpenDocument(lpszPathName))
{
// user has be alerted to what failed in OnOpenDocument
TRACE0("CDocument::OnOpenDocument returned FALSE./n");
pFrame->DestroyWindow();
return NULL;
}
pDocument->SetPathName(lpszPathName);
}

InitialUpdateFrame(pFrame, pDocument, bMakeVisible);
return pDocument;
}

16. CDocument* CDocTemplate::CreateNewDocument()

{
// default implementation constructs one from CRuntimeClass
if (m_pDocClass == NULL)
{
TRACE0("Error: you must override CDocTemplate::CreateNewDocument./n");
ASSERT(FALSE);
return NULL;
}
CDocument* pDocument = (CDocument*)m_pDocClass->CreateObject();
if (pDocument == NULL)
{
TRACE1("Warning: Dynamic create of document type %hs failed./n",
m_pDocClass->m_lpszClassName);
return NULL;
}
ASSERT_KINDOF(CDocument, pDocument);
AddDocument(pDocument);
return pDocument;
}

17. CFrameWnd* CDocTemplate::CreateNewFrame(CDocument* pDoc, CFrameWnd* pOther)

{
if (pDoc != NULL)
ASSERT_VALID(pDoc);
// create a frame wired to the specified document

ASSERT(m_nIDResource != 0); // must have a resource ID to load from
CCreateContext context;
context.m_pCurrentFrame = pOther;
context.m_pCurrentDoc = pDoc;
context.m_pNewViewClass = m_pViewClass;
context.m_pNewDocTemplate = this;

if (m_pFrameClass == NULL)
{
TRACE0("Error: you must override CDocTemplate::CreateNewFrame./n");
ASSERT(FALSE);
return NULL;
}
CFrameWnd* pFrame = (CFrameWnd*)m_pFrameClass->CreateObject();
if (pFrame == NULL)
{
TRACE1("Warning: Dynamic create of frame %hs failed./n",
m_pFrameClass->m_lpszClassName);
return NULL;
}
ASSERT_KINDOF(CFrameWnd, pFrame);

if (context.m_pNewViewClass == NULL)
TRACE0("Warning: creating frame with no default view./n");

// create new from resource
if (!pFrame->LoadFrame(m_nIDResource,
WS_OVERLAPPEDWINDOW | FWS_ADDTOTITLE, // default frame styles
NULL, &context))
{
TRACE0("Warning: CDocTemplate couldn't create a frame./n");
// frame will be deleted in PostNcDestroy cleanup
return NULL;
}

// it worked !
return pFrame;
}

18. BOOL CDocument::OnNewDocument()

{
if (IsModified())
TRACE0("Warning: OnNewDocument replaces an unsaved document./n");

DeleteContents();
m_strPathName.Empty(); // no path name yet
SetModifiedFlag(FALSE); // make clean

return TRUE;
}

19. BOOL CDocument::OnOpenDocument(LPCTSTR lpszPathName)

{
if (IsModified())
TRACE0("Warning: OnOpenDocument replaces an unsaved document./n");

CFileException fe;
CFile* pFile = GetFile(lpszPathName,
CFile::modeRead|CFile::shareDenyWrite, &fe);
if (pFile == NULL)
{
ReportSaveLoadException(lpszPathName, &fe,
FALSE, AFX_IDP_FAILED_TO_OPEN_DOC);
return FALSE;
}

DeleteContents();
SetModifiedFlag(); // dirty during de-serialize

CArchive loadArchive(pFile, CArchive::load | CArchive::bNoFlushOnDelete);
loadArchive.m_pDocument = this;
loadArchive.m_bForceFlat = FALSE;
TRY
{
CWaitCursor wait;
if (pFile->GetLength() != 0)
Serialize(loadArchive); // load me
loadArchive.Close();
ReleaseFile(pFile, FALSE);
}
CATCH_ALL(e)
{
ReleaseFile(pFile, TRUE);
DeleteContents(); // remove failed contents

TRY
{
ReportSaveLoadException(lpszPathName, e,
FALSE, AFX_IDP_FAILED_TO_OPEN_DOC);
}
END_TRY
DELETE_EXCEPTION(e);
return FALSE;
}
END_CATCH_ALL

SetModifiedFlag(FALSE); // start off with unmodified

return TRUE;
}

20. void DocTemplate::InitialUpdateFrame(CFrameWnd* pFrame, CDocument* pDoc,BOOL bMakeVisible)

{
// just delagate to implementation in CFrameWnd
pFrame->InitialUpdateFrame(pDoc, bMakeVisible);
}

21. void CFrameWnd::InitialUpdateFrame(CDocument* pDoc, BOOL bMakeVisible)
{
// if the frame does not have an active view, set to first pane
CView* pView = NULL;
if (GetActiveView() == NULL)
{
CWnd* pWnd = GetDescendantWindow(AFX_IDW_PANE_FIRST, TRUE);
if (pWnd != NULL && pWnd->IsKindOf(RUNTIME_CLASS(CView)))
{
pView = (CView*)pWnd;
SetActiveView(pView, FALSE);
}
}

if (bMakeVisible)
{
// send initial update to all views (and other controls) in the frame
SendMessageToDescendants(WM_INITIALUPDATE, 0, 0, TRUE, TRUE);

// give view a chance to save the focus (CFormView needs this)
if (pView != NULL)
pView->OnActivateFrame(WA_INACTIVE, this);

// finally, activate the frame
// (send the default show command unless the main desktop window)
int nCmdShow = -1; // default
CWinApp* pApp = AfxGetApp();
if (pApp != NULL && pApp->m_pMainWnd == this)
{
nCmdShow = pApp->m_nCmdShow; // use the parameter from WinMain
pApp->m_nCmdShow = -1; // set to default after first time
}
ActivateFrame(nCmdShow);
if (pView != NULL)
pView->OnActivateView(TRUE, pView, pView);
}

// update frame counts and frame title (may already have been visible)
if (pDoc != NULL)
pDoc->UpdateFrameCounts();
OnUpdateFrameTitle(TRUE);
}