How to get a pointer to color button

Question

I have a color button on toolbar, it was created in CMainFrame, how can I get a pointer to the color button which is CMFCColorMenuButton derived class from View, like the code below(part of MSOffice2007Demo Sample)? :

CMFCRibbonBar* pRibbon = ((CMainFrame*) GetTopLevelFrame())->GetRibbonBar();
ASSERT_VALID(pRibbon);

CMFCRibbonColorButton* pFontColorBtn = DYNAMIC_DOWNCAST(CMFCRibbonColorButton, pRibbon->FindByID(ID_FONT_COLOR));

Answer 1

The process to access button controls in a toolbar requires a number of steps to navigate to the control in question. The following list illustrates this:

1. Get a pointer to the frame window hosting the toolbar.
2. Get a pointer to the toolbar control.
3. [optional] Get the button index for a specific command ID.
4. Get a pointer to the button at the specified index.

5. Convert the base class button type to derived class.

   // Get pointer to mainframe window
   CMainFrame* pFrameWnd = DYNAMIC_DOWNCAST( CMainFrame, AfxGetMainWnd() );
   
   // Get pointer to the toolbar
   CBasePane* pPane = pFrameWnd->GetPane( AFX_IDW_TOOLBAR );
   CMFCToolBar* pToolBar = DYNAMIC_DOWNCAST( CMFCToolBar, pPane );
   
   // Find button index for command ID
   int index = pToolBar->CommandToIndex( ID_COLOR_PICKER );
   
   // Retrieve button
   CMFCToolBarButton* pButton = pToolBar->GetButton( index );
   
   // Convert button to appropriate type
   CMFCColorMenuButton* pColorButton = DYNAMIC_DOWNCAST( CMFCColorMenuButton,
                                                         pButton );
   

A few notes on the implementation:

Error handling has been omitted for brevity. Whenever there is a DYNAMIC_DOWNCAST the return value can be NULL and has to be checked. Likewise, the call to CommandToIndex can fail and requires error handling.

DYNAMIC_DOWNCAST is similar to a C++ dynamic_cast in that it evaluates whether a runtime type can be converted to another type. While not all Windows control relationships can be modeled as a C++ class hierarchy, MFC provides its own conversion tool: DYNAMIC_DOWNCAST.

The ID passed to the call to CommandToIndex is the command ID assigned to the CMFCColorMenuButton either through a resource script or at runtime, depending on how the control is created.