[MFC] Memorarea si restaurarea pozitiei ferestrei principale

[nmg]

Intrebare: Cum pot memora pozitia unei ferestre si utliza la urmatoare afisare a acesteia?

Raspuns: Implementarea unei astfel de comportament este extrem de simpla si implica utilizarea
functiilor virtuale OnDestroy() si ActivateFrame().

In functie de implementarea dorita, datele se pot salva intr-un fisier config sau in registry,
ca in cazul de fata.

Pentru salvarea pozitiei ferestrei se supraincarca functia OnDestroy():

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#define KEY         "Main"
#define SECTION "Setari\\Position"

void CMainFrame::OnDestroy()
{
   // get current position:
   WINDOWPLACEMENT wp;
   ::ZeroMemory(&wp, sizeof(wp));   
   GetWindowPlacement(&wp);

   // save data to registry
   theApp.WriteProfileBinary(SECTION, KEY, (LPBYTE)&wp, sizeof(WINDOWPLACEMENT));

   // destroy the window   
   CFrameWnd::OnDestroy();   
}


Pentru restaurarea ferestrei in pozitia initiala se supraincarca functia ActivateFrame (int nCmdShow):

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void CMainFrame::ActivateFrame(int nCmdShow)
{
    // do default:
    CFrameWnd::ActivateFrame(nCmdShow);

    // read position from the registry:
    UINT n = 0;
    WINDOWPLACEMENT* pWp = NULL;

    theApp.GetProfileBinary(SECTION, KEY, (LPBYTE*)&pWp, &n);

    // restore the window position:
    if(n == sizeof(WINDOWPLACEMENT))
        SetWindowPlacement(pWp);

    // clean up our mess:
    delete [] pWp;
}

[mesajflaviu]

O alta metoda de a memora/restaura pozitia ferestrei :

1. Se salveaza pozitia ferestrei in OnClose:

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void CMainFrame::OnClose()
{
   // TODO: Add your message handler code here and/or call default
   
    // Save main window position
    CWinApp* pApp = AfxGetApp();
    WINDOWPLACEMENT wp;
    GetWindowPlacement(&wp);
    pApp->WriteProfileInt("Frame", "Status", wp.showCmd);
    pApp->WriteProfileInt("Frame", "Top",    wp.rcNormalPosition.top);
    pApp->WriteProfileInt("Frame", "Left",   wp.rcNormalPosition.left);
    pApp->WriteProfileInt("Frame", "Bottom", wp.rcNormalPosition.bottom);
    pApp->WriteProfileInt("Frame", "Right",  wp.rcNormalPosition.right);

   CMDIFrameWnd::OnClose();
}

2. Se restaureaza in PreCreateWindow:

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BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)
{
   if( !CMDIFrameWnd::PreCreateWindow(cs) )
      return FALSE;
   // TODO: Modify the Window class or styles here by modifying
   //  the CREATESTRUCT cs

    // Restore main window position
    CWinApp* pApp = AfxGetApp();
    int s, t, b, r, l;

    // only restore if there is a previously saved position
    if ( -1 != (s = pApp->GetProfileInt("Frame", "Status",   -1)) &&
         -1 != (t = pApp->GetProfileInt("Frame", "Top",      -1)) &&
         -1 != (l = pApp->GetProfileInt("Frame", "Left",     -1)) &&
         -1 != (b = pApp->GetProfileInt("Frame", "Bottom",   -1)) &&
         -1 != (r = pApp->GetProfileInt("Frame", "Right",    -1)))
   {
      // restore the window's status
      pApp->m_nCmdShow = s;

      // restore the window's width and height
      cs.cx = r - l;
      cs.cy = b - t;

      // the following correction is needed when the taskbar is
      // at the left or top and it is not "auto-hidden"
      RECT workArea;
      SystemParametersInfo(SPI_GETWORKAREA, 0, &workArea, 0);

      l += workArea.left;
      t += workArea.top;

      // make sure the window is not completely out of sight
      int max_x = GetSystemMetrics(SM_CXSCREEN) - GetSystemMetrics(SM_CXICON);
      int max_y = GetSystemMetrics(SM_CYSCREEN) - GetSystemMetrics(SM_CYICON);

      cs.x = min(l, max_x);
      cs.y = min(t, max_y);
   }
   return TRUE;
}

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[mesajflaviu]

Prima solutie din acest topic funtioneaza pentru aplicatii SDI. O solutie imbunatatita care este OK si pentru MDI este urmatoarea:

1. Se creeaza o variabila membru te tip boolean pentru CMainFrame : m_bOnce , care se initializeaza in CMainFrame::PreCreateWindow cu valoarea TRUE : m_bOnce = TRUE.
2. In CMainFrame::DestroyWindow se salveaza pozitia ferestrei.
   

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   void CMainFrame::OnDestroy()
{
   SaveBarState(_T("bar_state"));
   WINDOWPLACEMENT wp;
   GetWindowPlacement(&wp);
   AfxGetApp()->WriteProfileBinary("MainFrame", "WP", (LPBYTE)&wp, sizeof(wp));

   CMDIFrameWnd::OnDestroy();   
}

3. In CMainFrame::OnShowWindow se restaureaza pozitia memorata a ferestrei. Variabila m_bOnce este folosita pentru a ne asigura ca acest lucru se face o singura data.
   

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   void CMainFrame::OnShowWindow(BOOL bShow, UINT nStatus)
{
   CMDIFrameWnd::OnShowWindow(bShow, nStatus);
   
   if(bShow && ! IsWindowVisible() && m_bOnce)
   {
      m_bOnce = FALSE;
      UINT nBytes = 0;
      WINDOWPLACEMENT *lwp;
      if(AfxGetApp()->GetProfileBinary("MainFrame", "WP", (LPBYTE*)&lwp, &nBytes))
      {
         SetWindowPlacement(lwp);
         delete []lwp;
      }
   }
}

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