Q141334: VSWAP32 Demos Multiple-View Switching in SDI
Article: Q141334
Product(s): Microsoft C Compiler
Version(s): 4.0,4.1,4.2,5.0,6.0
Operating System(s):
Keyword(s): kbcode kbfile kbSample kbDocView kbMFC kbVC400 kbVC500 kbVC600 kbGrpDSMFCATL
Last Modified: 02-JUL-2002
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The information in this article applies to:
- The Microsoft Foundation Classes (MFC), used with:
- Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0
- Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
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SUMMARY
=======
VSWAP32 demonstrates methods of switching between multiple views on a single
document in a single-document interface (SDI) application. VSWAP32 displays two
form views and a normal view that displays the list of data collected in the two
form views.
NOTE: This is the 32-bit version of this sample. There is also a 16-bit version
available called VSWAP.EXE.
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:
Visual C++ 6.0:
DownloadDownload Vcswap32.exe now
(http://download.microsoft.com/download/vc60pro/Sample/3/WIN98/EN-US/Vswap32.exe)
For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored on secure servers that prevent any unauthorized
changes to the file.
Visual C++ .NET:
DownloadDownload Vcswap32vcnet.exe now
(http://download.microsoft.com/download/visualstudionet/sample/1.17/win98mexp/en-us/Vcswap32vcnet.exe)
Release Date: June 26, 2002
For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored 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:
VSWAP32.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 document template, document,
and view during the call to ProcessShellCommand. The code added to the end of
InitInstance 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
ProcessShellCommand. Finally, the sample code triggers the OnInitialUpdate for
the extra views.
In this sample, both views persist for the lifetime of the application; however,
the application could create the new view dynamically.
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 step 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 SetToDoc, which actually updates the data
from the form view to the document by using MFC's DDX/DDV mechanisms in
DoDataExchange.
Sample Code
-----------
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 validation fails
if ( ! SaveActiveViewsData() )
{
return pActiveView;
}
m_nCurView = nIndex; // Store the new current view's index.
// Exchange view window ID's so RecalcLayout() works.
UINT temp = ::GetWindowLong(pActiveView->m_hWnd, GWL_ID);
::SetWindowLong(pActiveView->m_hWnd, GWL_ID,
::GetWindowLong(pNewView->m_hWnd, GWL_ID));
::SetWindowLong(pNewView->m_hWnd, GWL_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 other examples of applications that switch views, please refer to the
following samples:
COLLECT (SDI)
ENROLL (SDI)
VWRPLC32 (MDI)
SPLIT32 (Splitter).
For more information on DDX and DDV routines, please see Technical Note 26: DDX
and DDV Routines in the Microsoft Development Library.
(c) Microsoft Corporation 1999, All Rights Reserved.
Contributions by Jason Strayer, Microsoft Corporation
Additional query words: mfc Vcswap32 Vcswap32vcnet
======================================================================
Keywords : kbcode kbfile kbSample kbDocView kbMFC kbVC400 kbVC500 kbVC600 kbGrpDSMFCATL
Technology : kbAudDeveloper kbMFC
Version : :4.0,4.1,4.2,5.0,6.0
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