Advanced MFC Programming

Chapter 2. Menu
Adding Menu Resource
Sample 2.2\Menu demonstrates right-click menu implementation. It is a standard SDI application
generated by Application Wizard with all the default settings. This is the same with the previous sample.
We can also start from sample 2.1\Menu and add the new features that will be discussed below.
Like tool bar and dialog bar, a menu can be implemented starting from building menu resource. To add
a menu resource, We can execute Insert | Resource command in Developer Studio, select “menu” resource
type from the popped up dialog box, and click button “New”. Now a new menu resource with a default ID
will be added to the application. In the sample, this default ID is changed to IDR_MENU_POPUP, and a submenu
with four menu items is created. The newly created menu items are “Pop Up Item 1”, “Pop Up Item
2”, “Pop Up Item 3” and “Pop Up Item 4”, whose command IDs are ID__POPUPITEM1, ID__POPUPITEM2,
ID__POPUPITEM3 and ID__POPUPITEM4 respectively (Figure 2-1).
For right-click menu, we
don’t need to provide a
text for sub menu title
Add menu items here
Figure 2-1: Add menu resource for right-click menu
Trapping Right Button Clicking Event
The first step to implement a right-click menu is to detect mouse’s right clicking event, which is a
standard Windows event, and its corresponding message is WM_RBUTTONDOWN. To trap this message, we
need to implement message handler.
When we click mouse’s right button on a window, message WM_RBUTTONDOWN will be sent to that
window. This window could be any type: mainframe window, client window, dialog box, or even button.
We need to handle this message in the class that implements the window. For example, if we want to
handle right click in a dialog box, we need to add the message handler in a CDialog derived class, if we
want to handle it in the client window of an SDI application, we need to add the message handler in CView
derived class.
In our sample, right-clicking menu is implemented in the client window. So we need to trap message
WM_RBUTTONDOWN in class CMenuView.
Adding message handler for message WM_RBUTTONDOWN is similar to that of WM_COMMAND: first we need
to declare an afx_msg type member function OnRButtonDown(…), then use ON_RBUTTONDOWN macro to map
the message to this function. Finally, we need to implement the message handler. Please note that
OnRButtonDow(…) is the standard function name that will be automatically associated with message
WM_RBUTTONDOWN. When using ON_RBUTTONDOWN macro, we do not need to specify function name.
The above-mentioned procedure can be implemented through using Class Wizard as follows: after
invoking the Class Wizard, select class CMenuView, which is the class used to implement the client window.
There are a lot of virtual functions and messages listed in the “Messages” window. By scrolling the vertical
scroll bar, it is easy to find message WM_RBUTTONDOWN. Now highligh this message and click “Add function”
button. This will cause a new member function OnRButtonDown to be added to class CMenuView, and
message mapping macros to be added to the implementation file (See Figure 2-2).
In the sample, the newly added function is CMenuView::OnRButtonDown(…), which needs to be
modified to implement right-click menu. By default, this function does nothing but calling the message
handler implemented by the base class:
void CMenuView::OnRButtonDown(UINT nFlags, CPoint point)
{
CView::OnRButtonDown(nFlags, point);
}
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