Using IlvMenuItem
Menu bars, toolbars, and pop-up menus are composed of several entries, called menu items. Menus items are implemented by the
IlvMenuItem class, a subclass of
IlvGadgetItem. They can display a label, a bitmap, or any
IlvGraphic object. See
Gadget Items.
Creating Menu Items
The following code sample creates three menu items: one with a label, one with a bitmap, and one with an IlvGraphic object.
item1 = new IlvMenutItem("item1"); // Creates an item with a label.
item2 = new IlvMenuItem(bitmap); // Creates an item with a bitmap.
item3 = new IlvMenuItem(graphic); // Creates an item with a graphic.
A menu item can also be used as a separator. A separator is a line that divides a group of commands represented by menu items in a menu.
item4 = new IlvMenuItem(); // Creates a separator.
You can check whether an item is a separator or not using the
getType member function, as follows:
if (item->getType() == IlvSeparatorItem) {
...
}
Attaching a Submenu to a Menu Item
Any menu item that is not a separator can display a submenu. To attach a submenu to a menu item, use the member function
setMenu. When the menu item belongs to a pop-up menu, a small arrow next to it indicates that it provides access to a submenu.
New Menu Item with a Submenu
Associating a Callback with a Menu Item
When the user selects a menu item, its associated callback is invoked to perform an action. Each menu item can have a specific callback.
To attach a callback to a menu item, use one of the following member functions:
item->setCallback(myCallback);where myCallback is a function that might be described like this:
static void
myCallback(IlvGraphic* g, IlvAny data)
{
....
}
The
g parameter is the holder of the item that triggers the callback, that is, an instance of a subclass of
IlvAbstractMenu. The
data parameter is the client data of the menu item which you can install with the member function
setClientData.
Of course, it is useless to set a callback to a menu item separator or to a menu item that has a submenu, as these callbacks will never be called.
item->setCallbackName("myCallback"); In this case, the callback name "myCallback" must be registered with the container that holds the menu.
If a menu item does not have a callback, the Main callback associated with the menu, if any, is invoked. This allows you to perform the same action for each item of the menu. See
Associating a Callback with a Gadget.
Associating Mnemonics with Menu Items
You can associate a mnemonic letter with a menu item. Pressing the modifier key (Alt on PCs, and Meta on UNIX) and the mnemonic letter associated with a menu or toolbar item displays the attached pop-up menu. When a menu is open, pressing the mnemonic letter selects the corresponding command in that menu, that is, triggers the Menu Item callback.
Associating Accelerators with Menu Items
A pop-up menu item can be associated with an accelerator. An accelerator is a combination of a letter key with a modifier key. When the user presses the key combination, the Menu Item callback is directly accessed without the corresponding menu being opened.
An accelerator is composed of two parts: a key combination and the accelerator itself. The key combination appears beside its associated menu item.
For example, if you want to assign the key combination Ctrl+A to a menu item, use the following code:
item->setAcceleratorText("Ctrl+A");
item->setAcceleratorModifiers(0);
item->setAcceleratorKey(IlvCtrlChar('A'));
Version 6.3
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