MFC OnFileNew OnFileOpen過程分析程式碼（一）
原文：http://blog.csdn.net/teleinfor/article/details/1856725
對OnFileNew()/OnFileOpen()的MFC程式碼跟蹤簡析，簡析可能也談不上了，為了快速的理解MFC的實現思路以及文件檢視架構的應用，在學習的過程當中我也沒有進行學習理解的註解。不過細細閱讀整個的實現流程，相信你我都能理解掌握MFC的整體思路。以後有機會再進行註解吧。
文件的建立順序
A) OnFileNew()執行過程分析
1. void CWinApp::OnFileNew()
{
if (m_pDocManager != NULL)
m_pDocManager->OnFileNew();
}
註釋:MFC對ID_FILE_NEW選單的響應函式,系統預設操作.
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:如果跳過此函式而手動操作直接進入pTemplate->OpenDocumentFile(),那麼文件模版列表選擇對話方塊也就不會出現了.
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);
}