How to programmatically show dropdown-menu of ribbon button? - c++

Question

I have ribbon button with a set of sub-items added. Such items are displayed when the user clicks on the tiny arrow below the button. I'd like to display such dropdown-menu when the button itself is clicked. How can I do that?
My initial idea was to programmatically show the menu when the user clicks the button. I've been able to do the same on toolbars (here) but using a similar solution on ribbons creates an infinite recursion:
// ...
ON_COMMAND(ID_RIBBON_BUTTON, &MainFrame::OnButtonClicked)
// ...
CMFCRibbonPanel *panel = /* initialization */
CMFCRibbonButton *button = new CMFCRibbonButton(ID_RIBBON_BUTTON, "Caption");
panel->Add(button);
CMFCRibbonButton *item1 = new CMFCRibbonButton(ID_RIBBON_BUTTON, "Item 1");
button->AddSubItem(item1);
CMFCRibbonButton *item2 = new CMFCRibbonButton(ID_RIBBON_BUTTON, "Item 2");
button->AddSubItem(item2);
// ...
void MainFrame::OnButtonClicked()
{
if (auto button = static_cast<CMFCRibbonButton *>(m_ribbons.wndRibbonBar.FindByID(ID_RIBBON_BUTTON))) {
// button->OnClick({}); // <- causes infinite recursion
// What to do here?
}
}

Answer 1

The easiest way I've found so far is to use the protected method CMFCRibbonButton::OnShowPopupMenu. It implies deriving the CMFCRibbonButton class and changing the visibility of the method:
#include <afxribbonbutton.h>
class CMyMFCRibbonButton : public CMFCRibbonButton {
public:
using CMFCRibbonButton::CMFCRibbonButton;
virtual void OnShowPopupMenu() override {
CMFCRibbonButton::OnShowPopupMenu();
}
};
// ...
ON_COMMAND(ID_RIBBON_BUTTON, &MainFrame::OnButtonClicked)
// ...
CMFCRibbonPanel *panel = /* initialization */
CMyMFCRibbonButton *button = new CMyMFCRibbonButton(ID_RIBBON_BUTTON, "Caption");
panel->Add(button);
CMFCRibbonButton *item1 = new CMFCRibbonButton(ID_RIBBON_BUTTON, "Item 1");
button->AddSubItem(item1);
CMFCRibbonButton *item2 = new CMFCRibbonButton(ID_RIBBON_BUTTON, "Item 2");
button->AddSubItem(item2);
// ...
void MainFrame::OnButtonClicked()
{
if (auto button = static_cast<CMyMFCRibbonButton*>(m_ribbons.wndRibbonBar.FindByID(ID_RIBBON_BUTTON))) {
button->OnShowPopupMenu();
}
}