Q141333: VSWAP Demos Multiple-View Switching in SDI
Article: Q141333
Product(s): Microsoft C Compiler
Version(s): 1.5,1.51,1.52
Operating System(s):
Keyword(s): kbcode kbfile kbsample kbDocView kbMFC KbUIDesign kbVC150 kbVC152 kbGrpDSMFCATL kbNoUpd
Last Modified: 06-MAY-2001
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The information in this article applies to:
- The Microsoft Foundation Classes (MFC), used with:
- Microsoft Visual C++ for Windows, 16-bit edition, versions 1.5, 1.51, 1.52
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SUMMARY
=======
VSWAP demonstrates methods of switching between multiple views on a single
document in a single-document interface (SDI) application. VSWAP displays two
form views and a normal view that displays the list of data collected in the two
form views.
NOTE: This is the 16-bit version of this sample. There is an equivalent 32-bit
sample available under the name VSWAP32.
This sample application demonstrates using DDX/DDV (dialog data exchange/dialog
data validation), with correct document updating and data validation when
switching between views. It also correctly catches unsaved/unvalidated data when
the application is closed.
The following files are available for download from the Microsoft Download
Center:
Vswap.exe
For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft used the most current virus detection software available on the date of
posting to scan this file for viruses. Once posted, the file is housed on secure
servers that prevent any unauthorized changes to the file.
After downloading the file, use the following command to extract the sample and
build the appropriate directory structure:
VSWAP.EXE -d
MORE INFORMATION
================
The most important implementations of this are in:
CVswapApp::InitInstance
CVswapApp::SwitchView
CVswapApp::SaveActiveViewsData
The standard InitInstance code creates an initial frame, document, and view
during the call to OnFileNew. The code added to the end of the InitInstance in
this sample creates the view objects for the extra views used in this
application and stores their pointers in a CVswapApp member array. It then
cycles through a loop which creates the windows for the view objects. Each view
window is created with a unique child window ID and a CCreateContext object that
associates each view with the same CDocument object, which was created by
OnFileNew. Finally, the sample code triggers the OnInitialUpdate for the extra
views.
The SwitchView function created in this sample swaps the current view with a
previously hidden view. It accomplishes this by first switching their child
window IDs. This is necessary because MFC relies on the standard view pane
having the child window ID of AFX_IDW_PANE_FIRST. The rest of the code hides the
current view and tells MFC to repaint and begin using the new view.
The SaveActiveViewsData is used to save the information from the active view to
the document object. It is called by SwitchView whenever a view is switched.
SaveActiveViewsData subsequently calls the view's SetToDoc, which actually
updates the data from the form view to the document by calling UpdateData with
an argument of TRUE. This function uses the DDX/DDV functions specified in the
view's DoDataExchange.
Sample Code
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The SwitchView function is included here as a reference.
CView* CVswapApp::SwitchView( UINT nIndex )
{
ASSERT( nIndex >=0 && nIndex < NUMVIEWS );
CView* pNewView = m_pViews[nIndex];
CView* pActiveView =
((CFrameWnd*) m_pMainWnd)->GetActiveView();
if ( !pActiveView ) // No currently active view
return NULL;
if ( pNewView == pActiveView ) // Already there
return pActiveView;
// Update Doc's data if needed
// Don't change view if data valiation fails
if ( ! SaveActiveViewsData() )
{
return pActiveView;
}
m_nCurView = nIndex; // Store the new current view's index
// exchange view window IDs so RecalcLayout() works
UINT temp = ::GetWindowWord(pActiveView->m_hWnd, GWW_ID);
::SetWindowWord(pActiveView->m_hWnd, GWW_ID,
::GetWindowWord(pNewView->m_hWnd, GWW_ID));
::SetWindowWord(pNewView->m_hWnd, GWW_ID, temp);
// Display and update the new current view - hide the old one
pActiveView->ShowWindow(SW_HIDE);
pNewView->ShowWindow(SW_SHOW);
((CFrameWnd*) m_pMainWnd)->SetActiveView(pNewView);
((CFrameWnd*) m_pMainWnd)->RecalcLayout();
pNewView->Invalidate();
return pActiveView;
}
REFERENCES
==========
For examples of other applications that switch views, please refer to the
following SAMPLES:
COLLECT (SDI)
ENROLL (SDI)
VWRPLC (MDI)
SPLIT (Splitter).
For more information on DDX and DDV routines, please see Technical Note 26: DDX
and DDV Routines in the Microsoft Development Library.
For additional information, please see the following article(s) in the Microsoft
Knowledge Base:
Q99562 Switching Views in a Single Document Interface Program
(c) Microsoft Corporation 1999, All Rights Reserved.
Contributions by Jason Strayer, Microsoft Corporation
Additional query words: VSWAP VSWAP32
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Keywords : kbcode kbfile kbsample kbDocView kbMFC KbUIDesign kbVC150 kbVC152 kbGrpDSMFCATL kbNoUpdate
Technology : kbAudDeveloper kbMFC
Version : :1.5,1.51,1.52
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