MFC: Communicate with View from Dialog

Question

I want my Dialog to communicate with my existing view outside of an OK response (so using an apply or similar). I assume Messages are the best way to do this.

I'm sure there are not a lot of MFC questions these days, so I hope someone is able to help.

Creating a new project via the wizard, I add a dialog (let's say a CPropertySheet) that is spawned by the view.

MyPropertiesSheet ps(_T("MyPropertiesSheet"));

if (ps.DoModal() == IDOK) {
    // I don't care about this section
}

At first, I assumed that when I click 'apply' I would be able to send a message to the view and have it do something (as it was spawned in the view); however, I cannot pass messages directly to the view.

From the Dialog I use:

GetParent()->SendMessage(WM_BUTTON1, 0, 0);

I can catch the message within my MainFrm (a CmainFrame) which will launch the specified Button1() function, but I cannot catch the message in the view using the same code (below).

BEGIN_MESSAGE_MAP(CMainFrame, CMDIFrameWndEx)
    ...
    ON_MESSAGE(WM_BUTTON1, Button1)
END_MESSAGE_MAP()

It makes sense as I guess the View is a child of the MainFrm and the Dialog belongs to the MainFrm, not the View.

My Programming Windows with MFC (2nd ed), by Jeff Prosise, uses a custom OnCreate to get a reference to the View by creating it manually, but I really don't want to have to do this as it seems rather complex. I am sure I will end up creating a lot of problems that way. The default OnCreate seems to have no obvious reference to my view (included for example, but feel free to skip this).

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (CMDIFrameWndEx::OnCreate(lpCreateStruct) == -1)
        return -1;

    BOOL bNameValid;

    CMDITabInfo mdiTabParams;
    mdiTabParams.m_style = CMFCTabCtrl::STYLE_3D_ONENOTE; // other styles available...
    mdiTabParams.m_bActiveTabCloseButton = TRUE;      // set to FALSE to place close button at right of tab area
    mdiTabParams.m_bTabIcons = FALSE;    // set to TRUE to enable document icons on MDI taba
    mdiTabParams.m_bAutoColor = TRUE;    // set to FALSE to disable auto-coloring of MDI tabs
    mdiTabParams.m_bDocumentMenu = TRUE; // enable the document menu at the right edge of the tab area
    EnableMDITabbedGroups(TRUE, mdiTabParams);

    if (!m_wndMenuBar.Create(this))
    {
        TRACE0("Failed to create menubar\n");
        return -1;      // fail to create
    }

    m_wndMenuBar.SetPaneStyle(m_wndMenuBar.GetPaneStyle() | CBRS_SIZE_DYNAMIC | CBRS_TOOLTIPS | CBRS_FLYBY);

    // prevent the menu bar from taking the focus on activation
    CMFCPopupMenu::SetForceMenuFocus(FALSE);

    if (!m_wndToolBar.CreateEx(this, TBSTYLE_FLAT, WS_CHILD | WS_VISIBLE | CBRS_TOP | CBRS_GRIPPER | CBRS_TOOLTIPS | CBRS_FLYBY | CBRS_SIZE_DYNAMIC) ||
        !m_wndToolBar.LoadToolBar(theApp.m_bHiColorIcons ? IDR_MAINFRAME_256 : IDR_MAINFRAME))
    {
        TRACE0("Failed to create toolbar\n");
        return -1;      // fail to create
    }

    CString strToolBarName;
    bNameValid = strToolBarName.LoadString(IDS_TOOLBAR_STANDARD);
    ASSERT(bNameValid);
    m_wndToolBar.SetWindowText(strToolBarName);

    CString strCustomize;
    bNameValid = strCustomize.LoadString(IDS_TOOLBAR_CUSTOMIZE);
    ASSERT(bNameValid);
    m_wndToolBar.EnableCustomizeButton(TRUE, ID_VIEW_CUSTOMIZE, strCustomize);

    // Allow user-defined toolbars operations:
    InitUserToolbars(nullptr, uiFirstUserToolBarId, uiLastUserToolBarId);

    if (!m_wndStatusBar.Create(this))
    {
        TRACE0("Failed to create status bar\n");
        return -1;      // fail to create
    }
    m_wndStatusBar.SetIndicators(indicators, sizeof(indicators)/sizeof(UINT));

    // TODO: Delete these five lines if you don't want the toolbar and menubar to be dockable
    m_wndMenuBar.EnableDocking(CBRS_ALIGN_ANY);
    m_wndToolBar.EnableDocking(CBRS_ALIGN_ANY);
    EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndMenuBar);
    DockPane(&m_wndToolBar);


    // enable Visual Studio 2005 style docking window behavior
    CDockingManager::SetDockingMode(DT_SMART);
    // enable Visual Studio 2005 style docking window auto-hide behavior
    EnableAutoHidePanes(CBRS_ALIGN_ANY);

    // Load menu item image (not placed on any standard toolbars):
    CMFCToolBar::AddToolBarForImageCollection(IDR_MENU_IMAGES, theApp.m_bHiColorIcons ? IDB_MENU_IMAGES_24 : 0);

    // create docking windows
    if (!CreateDockingWindows())
    {
        TRACE0("Failed to create docking windows\n");
        return -1;
    }

    m_wndFileView.EnableDocking(CBRS_ALIGN_ANY);
    m_wndClassView.EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndFileView);
    CDockablePane* pTabbedBar = nullptr;
    m_wndClassView.AttachToTabWnd(&m_wndFileView, DM_SHOW, TRUE, &pTabbedBar);
    m_wndOutput.EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndOutput);
    m_wndProperties.EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndProperties);

    // set the visual manager and style based on persisted value
    OnApplicationLook(theApp.m_nAppLook);

    // Enable enhanced windows management dialog
    EnableWindowsDialog(ID_WINDOW_MANAGER, ID_WINDOW_MANAGER, TRUE);

    // Enable toolbar and docking window menu replacement
    EnablePaneMenu(TRUE, ID_VIEW_CUSTOMIZE, strCustomize, ID_VIEW_TOOLBAR);

    // enable quick (Alt+drag) toolbar customization
    CMFCToolBar::EnableQuickCustomization();

    if (CMFCToolBar::GetUserImages() == nullptr)
    {
        // load user-defined toolbar images
        if (m_UserImages.Load(_T(".\\UserImages.bmp")))
        {
            CMFCToolBar::SetUserImages(&m_UserImages);
        }
    }

    // enable menu personalization (most-recently used commands)
    // TODO: define your own basic commands, ensuring that each pulldown menu has at least one basic command.
    CList<UINT, UINT> lstBasicCommands;

    lstBasicCommands.AddTail(ID_FILE_NEW);
    lstBasicCommands.AddTail(ID_FILE_OPEN);
    lstBasicCommands.AddTail(ID_FILE_SAVE);
    lstBasicCommands.AddTail(ID_FILE_PRINT);
    lstBasicCommands.AddTail(ID_APP_EXIT);
    lstBasicCommands.AddTail(ID_EDIT_CUT);
    lstBasicCommands.AddTail(ID_EDIT_PASTE);
    lstBasicCommands.AddTail(ID_EDIT_UNDO);
    lstBasicCommands.AddTail(ID_APP_ABOUT);
    lstBasicCommands.AddTail(ID_VIEW_STATUS_BAR);
    lstBasicCommands.AddTail(ID_VIEW_TOOLBAR);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2003);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_VS_2005);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_BLUE);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_SILVER);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_BLACK);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_AQUA);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_WINDOWS_7);
    lstBasicCommands.AddTail(ID_SORTING_SORTALPHABETIC);
    lstBasicCommands.AddTail(ID_SORTING_SORTBYTYPE);
    lstBasicCommands.AddTail(ID_SORTING_SORTBYACCESS);
    lstBasicCommands.AddTail(ID_SORTING_GROUPBYTYPE);

    CMFCToolBar::SetBasicCommands(lstBasicCommands);

    // Switch the order of document name and application name on the window title bar. This
    // improves the usability of the taskbar because the document name is visible with the thumbnail.
    ModifyStyle(0, FWS_PREFIXTITLE);

    return 0;
}

I assume there must be a way to get a handle to my View from MainFrm.

I've tried:

auto pView = GetActiveView();
if (pView == NULL) {
    std::string error = "Unable to get Active View\n";
    TRACE(error.c_str());
}
else {
    pView->SendMessage(WM_BUTTON1, 0, 0);
}

but this is returning NULL (so I can't use that to send a message).

I'm not even sure I need this, but I am interested in why this is not working and why I can't get a handle to my View from the MainFrm.

Answer 1

For a simple solution, I would post your command WM_BUTTON1 with WM_COMMAND. Then the command is routed the MFC way MSDN ( MDI: Main frame, active child frame, active view, active document, application).
No need to handle and forward it in CMainframe. It does automatically for you.

In your CDialog:

AfxGetMainWnd()->PostMessage(WM_COMMAND, WM_BUTTON1, 0);

Add your handler in your CView

ON_COMMAND(WM_BUTTON1, &CMyView::OnButton)

Answer 2

No guarantees...from memory mostly. I haven't used CMDIFrameWndEx, only CMDIFrameWnd, but I assume it should work for the derived Ex variant...seemed like that was your main frame class.

// pseudo code

CMDIFrameWndEx* pFrame = DYNAMIC_DOWNCAST(CMDIFrameWndEx, AfxGetMainWnd()); // doesn't always work for OLE servers
if (pFrame)
{
   CMDIChileWnd* pMDIChild = pFrame->MDIGetActive();
   if (pMDIChild)
   {
      CYourView* pYourView = DYNAMIC_DOWNCAST(CYourView, pMDIChild->GetActiveView());
      if (pYourView)
      {
         // do something
      }
   }
}