Additional Combo MRU for Doc/View architecture

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Introduction

One day I had to create an SDI application that requires an MRU feature implemented in a combo box on the document form view. I'm not an advanced VC programmer so I don't pretend that this is the best solution. This article is for beginners that search for such an example.

What is to be done ?

Create an usual SDI application using VC wizard. For my project I specified an MRU size of 5.

Override the default OnCmdMsg message dispatcher of your application object (CWinApp derived) using the Class Wizard. In my example the application object is CTestFormApp.

BOOL CTestFormApp::OnCmdMsg(UINT nID, int nCode, 
    void* pExtra, AFX_CMDHANDLERINFO* pHandlerInfo) 
{
 BOOL temp = CWinApp::OnCmdMsg(nID, nCode, pExtra, pHandlerInfo);

 if (nID >= ID_FILE_MRU_FILE1 && nID <= ID_FILE_MRU_FILE1 + 4) 
 if (nCode == CN_COMMAND) UpdateComboMRU();

 return temp;

} 

The implementation of the UpdateComboMRU looks like this:

#include "afxpriv.h"    // needed because there is a forward class 
    //declaration of CRecentFileList

CTestFormApp::UpdateComboMRU()
{ 
  CComboBox & combo=((CTestFormView*)(
    (CFrameWnd*)m_pMainWnd)->GetActiveView())->m_ComboMRU;
  CString x;
  combo.ResetContent();
  for (int i = 0; i < m_pRecentFileList->m_nSize; i++)
  { if (!m_pRecentFileList->GetDisplayName(x, i, NULL, NULL))
   break;
  combo.AddString(x); // update the combo from MRU object
  }
  combo.SetCurSel(0);  // select first MRU file
}

CTestFormView is my document view class and m_ComboMRU is a CComboBox object displayed in the view.

In order to work things out the following calls are needed:

((CTestFormApp*)AfxGetApp())->UpdateComboMRU();

from:

• the form view OnInitialUpdate
• the document OnOpenDocument
• the document DoSave

just like this:

void CTestFormView::OnInitialUpdate()
{
 CFormView::OnInitialUpdate();
 ((CTestFormApp*)AfxGetApp())->UpdateComboMRU();
 GetParentFrame()->RecalcLayout();
 ResizeParentToFit();
}

BOOL CTestFormDoc::OnOpenDocument(LPCTSTR lpszPathName) 
{
 if (!CDocument::OnOpenDocument(lpszPathName))
  return FALSE;
 
 ((CTestFormApp*)AfxGetApp())->UpdateComboMRU();
 
 return TRUE;
}

BOOL CTestFormDoc::DoSave(LPCTSTR lpszPathName, BOOL bReplace)
{
 BOOL temp = CDocument::DoSave(lpszPathName, bReplace);
 ((CTestFormApp*)AfxGetApp())->UpdateComboMRU();
 return temp;
}

You need to override DoSave. There's an interesting article about this on this site:

• CDocument::DoSave revealed by Nishant S