Menu Templates
Menu templates are a fundamental concept in Windows application development, allowing developers to define the structure and content of application menus in a declarative way. These templates are typically created using resource editors and are compiled into the application's executable or a separate resource file.
Resource Editor Usage
Most integrated development environments (IDEs) for Windows development, such as Visual Studio, provide a visual menu editor. This editor allows you to:
- Create new menus and submenus.
- Add menu items with specific text and associated command IDs.
- Define check marks, grayed-out states, and other item properties.
- Organize menu items into logical groups using separators.
- Assign keyboard accelerators (shortcut keys) to menu items.
Menu Template Structure
Menu templates are stored in a resource script file (typically with a .rc extension) and are compiled into a binary format that the Windows operating system can load at runtime. A simplified representation of a menu template in a resource script might look like this:
IDR_MYMENU MENU
BEGIN
POPUP "&File"
BEGIN
MENUITEM "&New", ID_FILE_NEW
MENUITEM "&Open", ID_FILE_OPEN
MENUITEM SEPARATOR
MENUITEM "&Save", ID_FILE_SAVE
MENUITEM "Save &As...", ID_FILE_SAVE_AS
MENUITEM SEPARATOR
MENUITEM "E&xit", ID_FILE_EXIT
END
POPUP "&Edit"
BEGIN
MENUITEM "&Undo\tCtrl+Z", ID_EDIT_UNDO
MENUITEM "&Redo\tCtrl+Y", ID_EDIT_REDO
MENUITEM SEPARATOR
MENUITEM "Cu&t\tCtrl+X", ID_EDIT_CUT
MENUITEM "&Copy\tCtrl+C", ID_EDIT_COPY
MENUITEM "&Paste\tCtrl+V", ID_EDIT_PASTE
END
POPUP "&Help"
BEGIN
MENUITEM "&About...", ID_HELP_ABOUT
END
END
Key Elements in Menu Templates
POPUP: Defines a top-level menu (e.g., "File", "Edit"). The ampersand (&) before a character indicates that this character will be underlined and can be used as an accelerator key (e.g., Alt+F for the "File" menu).MENUITEM: Defines an individual menu item. It includes the text for the item and a unique identifier (e.g.,ID_FILE_NEW) that will be used by the application to process commands.SEPARATOR: Inserts a horizontal line to visually separate groups of menu items.\tAcceleratorKey: Appends a keyboard shortcut to the menu item text (e.g.,\tCtrl+Z).
Loading Menus
In your application code, you typically load the menu template using the LoadMenu API function, passing the resource identifier (e.g., IDR_MYMENU). This function returns a handle to the menu resource, which can then be attached to a window using SetMenu.
Note on Command IDs
Command IDs are typically defined as constants in a header file (e.g., resource.h) to ensure consistency between the resource script and your application code. These IDs are sent as wParam in WM_COMMAND messages when a menu item is selected.
Advanced Menu Features
Menu templates can also support more advanced features:
- Check Marks: Menu items can be displayed with a check mark next to them, indicating an enabled state or option selection. This is often controlled programmatically after the menu is loaded.
- Grayed-Out Items: Menu items can be grayed out to indicate that they are currently unavailable.
- Owner-Drawn Menus: For highly customized menu item appearances, you can use owner-drawn menus where your application is responsible for drawing the menu item.