MFC Doc/View笔记(一) 打开文件代码跟踪

VC2008 sp1，向导生成的doc/view MDI应用程序，主线程继承自CWinAppEx。

菜单选择打开文件，首先是App响应ID_FILE_OPEN命令，从事件映射：

ON_COMMAND(ID_FILE_OPEN, &CWinAppEx::OnFileOpen)

可以看到执行的是CWinAppEx::OnFileOpen()。在CWinAppEx类里没找到OnFileOpen，应该直接继承CWinApp的OnFileOpen。找到代码如下：

void CWinApp::OnFileOpen()

{

ENSURE(m_pDocManager != NULL);

m_pDocManager->OnFileOpen();

}

可以看到里面又调用CDocManager的OnFileOpen()。在此处加个断点，作为跟踪的起点。用菜单打开一个文件开始跟踪。F11进入CDocManager::OnFileOpen()，看到先打开选择文件的对话框，选择文件得到文件名再调用CWinApp的OpenDocumentFile()，代码如下：

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

}

进了CWinApp::OpenDocumentFile，我日，又转到CDocManager的OpenDocument()

CDocument* CWinApp::OpenDocumentFile(LPCTSTR lpszFileName)

{

ENSURE_VALID(m_pDocManager);

return m_pDocManager->OpenDocumentFile(lpszFileName);

}

一个CDocManager可能注册了了多个template，比如说一个应用可以打开文本，也可以打开图片。CDocManager::OpenDocumentFile()先不知道打开的是什么文件，不知道是用哪一个template来操作。一个个尝试匹配，找到最合适的那个。细节暂时忽略，应该是按注册的扩展名。

CDocument* CDocManager::OpenDocumentFile(LPCTSTR lpszFileName)

{

if (lpszFileName == NULL)

{

AfxThrowInvalidArgException();

}

// 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;

Checked::tcsncpy_s(szTemp, _countof(szTemp), lpszFileName, _TRUNCATE);

LPTSTR lpszLast = _tcsrchr(szTemp, '\"');

if (lpszLast != NULL)

*lpszLast = 0;

if( AfxFullPath(szPath, szTemp) == FALSE )

{

ASSERT(FALSE);

return NULL; // We won't open the file. MFC requires paths with

             // length < _MAX_PATH

}

TCHAR szLinkName[_MAX_PATH];

if (AfxResolveShortcut(AfxGetMainWnd(), szPath, szLinkName, _MAX_PATH))

Checked::tcscpy_s(szPath, _countof(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 posOpenDoc = pOpenDocument->GetFirstViewPosition();

if (posOpenDoc != NULL)

{

CView* pView = pOpenDocument->GetNextView(posOpenDoc); // get first one

ASSERT_VALID(pView);

CFrameWnd* pFrame = pView->GetParentFrame();

if (pFrame == NULL)

TRACE(traceAppMsg, 0, "Error: Can not find a frame for document to activate.\n");

else

{

pFrame->ActivateFrame();

if (pFrame->GetParent() != NULL)

{

CFrameWnd* pAppFrame;

if (pFrame != (pAppFrame = (CFrameWnd*)AfxGetApp()->m_pMainWnd))

{

ASSERT_KINDOF(CFrameWnd, pAppFrame);

pAppFrame->ActivateFrame();

}

}

}

}

else

TRACE(traceAppMsg, 0, "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);

}

那个pOpenDocument没看明白，先不管它。知道进了CDocTemplate的OpenDocumentFile就行。我这里是MDI程序，进的是CMultiDocTemplate::OpenDocumentFileCDocument()：

CMultiDocTemplate::OpenDocumentFile(LPCTSTR lpszPathName,

BOOL bMakeVisible)

{

CDocument* pDocument = CreateNewDocument();

if (pDocument == NULL)

{

TRACE(traceAppMsg, 0, "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

TRACE(traceAppMsg, 0, "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

TRACE(traceAppMsg, 0, "CDocument::OnOpenDocument returned FALSE.\n");

pFrame->DestroyWindow();

return NULL;

}

pDocument->SetPathName(lpszPathName);

}

InitialUpdateFrame(pFrame, pDocument, bMakeVisible);

return pDocument;

}

上面先分别用CreateNewDocument()和CreateNewFrame()创建了文档和视图的框架。暂时没有跟踪进去如何创建，反正知道这时候Doc和View(应该在Frame里面创建了)的实例都已经存在了。之后pDocument->OnOpenDocument()执行打开操作，再InitialUpdateFrame()更新窗口。

注意CDocument的OnOpenDocument() 缺省有一个重载，可能需用改写，因为不一定用它内置的CArchive串行化方法保存文件。

void CDocTemplate::InitialUpdateFrame(CFrameWnd* pFrame, CDocument* pDoc,

BOOL bMakeVisible)

{

// just delagate to implementation in CFrameWnd

pFrame->InitialUpdateFrame(pDoc, bMakeVisible);

}

进CFrameWnd::InitialUpdateFrame看看窗口咋初始化：

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);

}

这里又发消息WM_INITIALUPDATE给里面的View窗口，这是我要关注的地方了，刚才开始就是不知道View怎么初始化，才发狠心跟踪代码，这里终于找到了。重载一下OnInitialUpdate()函数，这应该是做事的地方了。

void CMyView::OnInitialUpdate()

{

CView::OnInitialUpdate();

// TODO: 在此添加专用代码和/或调用基类

}

瞟一眼：CView::OnInitialUpdate：

void CView::OnInitialUpdate()

{

OnUpdate(NULL, 0, NULL);        // initial update

}

还有啊，再瞟一眼CView::OnUpdate

void CView::OnUpdate(CView* pSender, LPARAM /*lHint*/, CObject* /*pHint*/)

{

ASSERT(pSender != this);

UNUSED(pSender);     // unused in release builds

// invalidate the entire pane, erase background too

Invalidate(TRUE);

}

这回差不多到头了。Invalidate应该会引发WM_PAINT消息，后面该是OnPaint()的事了。

思路大致清楚了。虽然这个Doc/View框架很复杂，就打开文件及显示内容这一部分来说，要关注的就是Doc在OnOpenDocument()读入数据，View在OnInitialUpdate()里初始化，OnPaint()里做显示。至于Doc/View里做内容修改与交互，以及文档的保存，下一步再研究。

PS:转自：http://skywolfblog.blog.163.com/blog/static/1779021802012222114736392/