Describe workflow of a typical MFC Application that supports Doc/View?

Doc-view modules

MFC doc-view application can be created by MFC wizard. We have seen how to create a single document interface SDI application using wizard in our previous module. MFC wizard creates each class and adds functions and events to support the minimal functionalities. However doc-view application can be created manually and now we want to understand the work function of each class. This module will help developer to write a minimal doc-view application from scratch.

A doc-view application should conain -

An application class instance derived from CWinApp class
A frame window derived from CFrameWnd class
A document class to hold the state and content of the document
A view class to represent the view of the document

CWinApp Application class

CWinApp should override and implement this functon.

CWinApp::InitInstance - Main application classs should override InitInstance() and implement the basic requirement. It should process command line arguments and create a SDI or MDI frame window.

CWinApp should handle these event codes and

OnFileNew() - New file with event code ID_FILE_NEW
OnFileOpen() - Open an existing file from disk using code ID_FILE_OPEN
OnAppAbout() - To show an about dialog with event code ID_APP_ABOUT

BEGIN_MESSAGE_MAP(CMySDIApp, CWinApp)
	ON_COMMAND(ID_APP_ABOUT, OnAppAbout)
	ON_COMMAND(ID_FILE_NEW, CWinApp::OnFileNew)
	ON_COMMAND(ID_FILE_OPEN, CWinApp::OnFileOpen)
END_MESSAGE_MAP()

CMySDIApp::CMySDIApp()
{
}

CMySDIApp theApp;

BOOL CMySDIApp::InitInstance()
{
	AfxEnableControlContainer();

#ifdef _AFXDLL
	Enable3dControls();
#else
	Enable3dControlsStatic();
#endif


	SetRegistryKey(_T("Local AppWizard-Generated Applications"));

	LoadStdProfileSettings();

	CSingleDocTemplate* pDocTemplate;
	pDocTemplate = new CSingleDocTemplate(
		IDR_MAINFRAME,
		RUNTIME_CLASS(CMySDIDoc),
		RUNTIME_CLASS(CMainFrame),
		RUNTIME_CLASS(CMySDIView));
	AddDocTemplate(pDocTemplate);

	// 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 one and only window has been initialized, so show and update it.
	m_pMainWnd->ShowWindow(SW_SHOW);
	m_pMainWnd->UpdateWindow();

	return TRUE;
}

CFrameWnd Window class

Programmer should implement and override OnCreate() event.

OnCreate - It is called when window is created.

Programmer should implement MFC OnCreate() event map.

ON_WM_CREATE - MFC Event map for OnCeate.

IMPLEMENT_DYNCREATE(CMainFrame, CFrameWnd)

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
	ON_WM_CREATE()
END_MESSAGE_MAP()

static UINT indicators[] =
{
	ID_SEPARATOR,           // status line indicator
	ID_INDICATOR_CAPS,
	ID_INDICATOR_NUM,
	ID_INDICATOR_SCRL,
};

/////////////////////////////////////////////////////////////////////////////
// CMainFrame construction/destruction

CMainFrame::CMainFrame()
{
}

CMainFrame::~CMainFrame()
{
}

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
	if (CFrameWnd::OnCreate(lpCreateStruct) == -1)
		return -1;
	
	if (!m_wndToolBar.CreateEx(this, TBSTYLE_FLAT, WS_CHILD | WS_VISIBLE | CBRS_TOP
		| CBRS_GRIPPER | CBRS_TOOLTIPS | CBRS_FLYBY | CBRS_SIZE_DYNAMIC) ||
		!m_wndToolBar.LoadToolBar(IDR_MAINFRAME))
	{
		TRACE0("Failed to create toolbar\n");
		return -1;      // fail to create
	}

	if (!m_wndStatusBar.Create(this) ||
		!m_wndStatusBar.SetIndicators(indicators,
		  sizeof(indicators)/sizeof(UINT)))
	{
		TRACE0("Failed to create status bar\n");
		return -1;      // fail to create
	}

	// TODO: Delete these three lines if you don't want the toolbar to
	//  be dockable
	m_wndToolBar.EnableDocking(CBRS_ALIGN_ANY);
	EnableDocking(CBRS_ALIGN_ANY);
	DockControlBar(&m_wndToolBar);

	return 0;
}

BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)
{
	if( !CFrameWnd::PreCreateWindow(cs) )
		return FALSE;
	return TRUE;
}

CDocument class

CDocument implements these member functions

CDocument - Construcor and destructor
OnNewDocument - Event for new document creation. Called during a new applicaton start or selecting new document menu
Serialize- Event saving or retrieving document from file. Called by framework in OnFileOpen() and OnFileSave().

///////////////////////////////////////////
// CMySDIDoc

IMPLEMENT_DYNCREATE(CMySDIDoc, CDocument)

BEGIN_MESSAGE_MAP(CMySDIDoc, CDocument)

END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CMySDIDoc construction/destruction

CMySDIDoc::CMySDIDoc()
{
}

CMySDIDoc::~CMySDIDoc()
{
}

BOOL CMySDIDoc::OnNewDocument()
{
	if (!CDocument::OnNewDocument())
		return FALSE;

    m_strFile = "Untitled";
	return TRUE;
}



/////////////////////////////////////////////////////////////////////////////
// CMySDIDoc serialization

void CMySDIDoc::Serialize(CArchive& ar)
{
	if (ar.IsStoring())
	{
		m_strFile = ar.GetFile()->GetFilePath();
		AfxMessageBox("Save:"+m_strFile);
	}
	else
	{
		m_strFile = ar.GetFile()->GetFilePath();
		AfxMessageBox("Load:"+m_strFile);
	}
}

CView class

CView implements these member functions

PreCreateWindow - Override Window attributes or pass the call to base class function.
OnDraw - Actual drawing work for window and printer DC.
OnPreparePrinting - Prining attributes override and print dialog by calling DoPreparePrinting
OnBeginPrinting - Prining or previewing startup call
OnEndPrinting - Prining or previewing cleanup call

CView implements these application event handlers functions

ID_FILE_PRINT - Printinging from menu/toolbar call event base CView::OnFilePrint.
ID_FILE_PRINT_DIRECT - Dirent printing using command line call base event CView::OnFilePrint.
ID_FILE_PRINT_PREVIEW - Print preview from menu/toolbar call CView::OnFilePrintPreview.

/////////////////////////////////////////////////////////////////////////////
// CMySDIView

IMPLEMENT_DYNCREATE(CMySDIView, CView)

BEGIN_MESSAGE_MAP(CMySDIView, CView)
	ON_COMMAND(ID_FILE_PRINT, CView::OnFilePrint)
	ON_COMMAND(ID_FILE_PRINT_DIRECT, CView::OnFilePrint)
	ON_COMMAND(ID_FILE_PRINT_PREVIEW, CView::OnFilePrintPreview)
END_MESSAGE_MAP()

CMySDIView::CMySDIView()
{
}

CMySDIView::~CMySDIView()
{
}

BOOL CMySDIView::PreCreateWindow(CREATESTRUCT& cs)
{
  return CView::PreCreateWindow(cs);
}

void CMySDIView::OnDraw(CDC* pDC)
{
	RECT rect;
	CMySDIDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	pDC->GetWindow()->GetClientRect(&rect);
	pDC->DrawText(pDoc->m_strFile, &rect, 0);
}

BOOL CMySDIView::OnPreparePrinting(CPrintInfo* pInfo)
{
  return DoPreparePrinting(pInfo);
}

void CMySDIView::OnBeginPrinting(CDC* pDC, CPrintInfo* pInfo)
{
}

void CMySDIView::OnEndPrinting(CDC* pDC, CPrintInfo* pInfo)
{
}