8.3 The document framework creation

The originated class of document, view, main window are need to create the framework of document, which unites the numerated classes.

The framework of SDI-document is an object of CSingleDocTemplate class. Its constructor:

CSingleDocTemplate::CSingleDocTemplate( UINT nIDResource, CRuntimeClass* pDocClass, CRuntimeClass* pFrameClass, CRuntimeClass* pViewClass );

The Parameters:

nIDResource   Specifies the ID of the resources used with the document type. This may include menu, icon, accelerator table, and string resources.

The string resource consists of up to seven substrings separated by the '\n' character (the '\n' character is needed as a placeholder if a substring is not included; however, trailing '\n' characters are not necessary); these substrings describe the document type. For information about the substrings, see CDocTemplate::GetDocString. This string resource is found in the application's resource file. For example Listing 8.3:

Listing 8.3 The example string, defining the resources, linked to the document

// MYCALC.RC

STRINGTABLE PRELOAD DISCARDABLE

BEGIN

IDR_MAINFRAME "MyCalc Windows Application\nSheet\nWorksheet\n Worksheets (*.myc)\n.myc\nMyCalcSheet\n MyCalc Worksheet"

END

The string is described in the following sequence:

1. The window header;

2. Default name of document (Untitled otherwise);

3. The name of document type;

4. The name of file filter (“File of type”);

5. The extension document files (f.e. “*.txt”);

6. The file’s ID in registration database;

7. The type file names in registration database.

pDocClass   Points to the CRuntimeClass object of the document class. This class is a CDocument-derived class you define to represent your documents.

pFrameClass   Points to the CRuntimeClass object of the frame window class. This class can be a CFrameWnd-derived class, or it can be CFrameWnd itself if you want default behavior for your main frame window.

pViewClass   Points to the CRuntimeClass object of the view class. This class is a CView-derived class you define to display your documents.

8.4 The initiation of application

Earlier, we have all the initiation in the function, derived from WinApp::InitInstance(). Now, it has the other sequence. See example in Listing 8.4:

Listing 8.4 The InitInstance() function implementation in Document / View concept

BOOL CApp::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.

SetDialogBkColor(); // Set dialog background color to gray

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.

CSingleDocTemplate* pDocTemplate; pDocTemplate = new CSingleDocTemplate(

IDR_MAINFRAME,

RUNTIME_CLASS(CSampleDoc),

RUNTIME_CLASS(CMainWin), // main SDI frame window

RUNTIME_CLASS(CSampleView));

AddDocTemplate(pDocTemplate); // create a new (empty) document

OnFileNew();

if (m_lpCmdLine[0] != '\0')

{ // TODO: add command line processing here }

return TRUE;}

The document storing and loading

CObject class contains Serialize() function, which automatically called on document saving or loading. CArchive class automates the functions to work with files and contains the pverloaded input and output in form of flow insertion operations: “<<” and “>>”.

virtual void CObject::Serialize( CArchive& ar ); Here Parameter ar   - CArchive object to serialize to or from.

You must override Serialize for each class that you intend to serialize. The overridden Serialize must first call the Serialize function of its base class.

You must also use the DECLARE_SERIAL macro in your class declaration, and you must use the IMPLEMENT_SERIAL macro in the implementation.

Use CArchive::IsLoading or CArchive::IsStoring to determine whether the archive is loading or storing. Their prototypes:

BOOL CArchive::IsLoading( ) const;

Return Value is nonzero if the archive is currently being used for loading; otherwise 0.

BOOL CArchive::IsStoring( ) const;

Return Value is nonzero if the archive is currently being used for storing; otherwise 0.

Inside of Serialize() function, there is used the operators “<<” and “>>”. See Listing 8.5

Listing 8.5 The example for CObject::Serialize

void CAge::Serialize( CArchive& ar )

{

CObject::Serialize( ar );

if( ar.IsStoring() )

ar << m_years;

else

ar >> m_years;

}

Some functions of CDocument class

Documents are part of the framework's standard command routing and consequently receive commands from standard user-interface components (such as the File Save menu item). A document receives commands forwarded by the active view. If the document doesn't handle a given command, it forwards the command to the document template that manages it.

When a document's data is modified, each of its views must reflect those modifications. CDocument provides the UpdateAllViews member function for you to notify the views of such changes, so the views can repaint themselves as necessary. The framework also prompts the user to save a modified file before closing it.

UpdateAllViews() function notifies all views that document has been modified.

void CDocument::UpdateAllViews

(CView* pSender, LPARAM lHint = 0L, CObject* pHint = NULL );

Parameters:

pSender   Points to the view that modified the document, or NULL if all views are to be updated.

lHint   Contains information about the modification.

pHint   Points to an object storing information about the modification.

SetModifiedFlag() sets a flag indicating that you have modified the document since it was last saved.

void CDocument::SetModifiedFlag( BOOL bModified = TRUE );

Parameter: bModified   Flag indicating whether the document has been modified.

Some functions of CView class

The CView class provides the basic functionality for programmer-defined view classes. A view is attached to a document and acts as an intermediary between the document and the user: the view renders an image of the document on the screen and interprets user input as operations upon the document. The view also renders the image for both printing and print preview.

The one of most usable function is GetDocument(). Return Value is a pointer to the CDocument object associated with the view. NULL if the view is not attached to a document.

CDocument *CView::GetDocument( ) const;