Volume 7A: XView Programming Manual

11

Menus

Menus play an important role in an application’s user interface. An OPEN LOOK menu may

display text or graphics. Menus may be attached to most XView objects such as menu but-

tons, scrollbars or text subwindows, or they may exist independently from objects and be

displayed on demand.

The user may cause a menu to be pinned up by selecting an optional pushpin in the pop-up

menu. When this happens, the menu is taken down and a corresponding command frame is

put up at the same location. Panel items in the pinup window correspond to the menu items

in the menu. Once a menu has been pinned up, the user continues to interact with it just as if

the menu were popped up each time. Menus that are used frequently are good candidates for

having pushpins so the user does not have to repeat the sequence of redisplaying the menu to

make selections.

OPEN LOOK requires that menus have titles. Menus or submenus that originate from menu

buttons or pullright items do not need to have titles, since the name of the menu button or

menu item acts as the title.

Fonts may not be specified in either menu items or menu titles; menu items follow the same

constraints outlined for panel buttons. However, if text is not used, then menu items may

contain graphic images, in which case, the font is of no concern. That is, you could specify a

Server_image that has a string rendered in a particular font.

11.1 Menu Types

There are three different types of menus: pop-up, pulldown, and pullright menus. The gen-

eral term pop-up menu may describes all three types in certain contexts since menus are

popped up. However, pulldown and pullright menus have distinct characteristics that make

them unique.

Menus

Menus 273

11.1.1 Pop-up Menus

Pop-up menus are displayed when the user selects the MENU mouse button over XView

objects such as scrollbars or text subwindows. An OPEN LOOK window manager also utilizes

pop-up menus in the root window and from base frame title bars. XView objects handle the

display of menus automatically. Applications may wish to track ACTION_MENU events in

objects such as canvases and display their own pop-up menus. Figure 11-1, from the OPEN

LOOK

GUI Specification Guide, shows a Window menu-generated from the title bar of an

OPEN LOOK base frame.

Figure 11-1. The Window menu

11.1.2 Pulldown Menus

Pulldown menus are attached to menu buttons. Menu buttons have a set of choices associ-

ated with them that the user can access only via the pulldown menu. When the user presses

the MENU mouse button over a menu button, the choices are displayed in the form of a pull-

down menu. If the menu button is selected using the SELECT button, the default menu item

is selected. See Chapter 7, Panels, for details on creating menu buttons. Figure 11-2, from

the OPEN LOOK GUI Specification Guide, shows sample pulldown menus activated from a

menu button.

11.1.3 Pullright Menus

OPEN LOOK provides for items in the menu to have pullright menus associated with them.

Also called cascading menus, these menus are activated from the user dragging the MENU

mouse button to the right of a menu item that has an arrow pointing to the right. The cascad-

ing menu that results is a pop-up menu that can also have menu items with pullrights atta-

ched. Figure 11-3, from the OPEN LOOK GUI Specification Guide, shows a pullright menu

originating from a menu item in a pulldown menu.

274 XView Programming Manual

Figure 11-2. Menu buttons each with a pulldown menu

Figure 11-3. Pushpins in a menu and a submenu

Menus

Menus 275

11.2 Menu Items

In addition to the menu types, there are different types of menu items: choice, exclusive, and

nonexclusive. The different menu item types may be associated with each type of menu.

Each menu has a default selection associated with it. This item is displayed uniquely from

other menu items and designates a default action to take if the user wants to select the menu

without displaying it (see pulldown menus below). Typically, the 0th item in the menu is the

default, but that may be changed either by the application or by the user.

11.2.1 Choice Items

The choice item is the default menu item type used when a menu is created. The default

selection in a menu has a ring around it. When a pop-up menu is displayed, it is positioned

so that the mouse is pointing at the default item. Choice menu items may have pullright

menus associated with them, in which case there is a pullright arrow at the right side of the

item. If the selection of a menu item brings up a dialog box (command frame), then the label

for the menu item typically ends in ellipses ( . . . ).

11.2.2 Exclusive Items

When a choice item is selected, an action is taken and the menu forgets about it. Exclusive

menu items retain the fact that they are selected even after the menu has popped down. If the

user selects a new item, the new item is remembered. Because this is an exclusive menu,

only one choice may be selected at a time. The default item is indicated by a double-lined

box around the item. Figure 11-4 is from the

OPEN LOOK GUI Specification Guide.

Figure 11-4. Exclusive settings on a menu

276 XView Programming Manual

When exclusive settings are used on menus, the current choice has a bold border when the

pointer is not on a menu choice. When the user drags the pointer onto other settings, the bold

border follows the pointer. Exclusive choice menus may not have items with pullright

menus.

11.2.3 Nonexclusive Items

Also called toggle items, menus that have toggle items support multiple choices from the

menu to be selected at the same time. That is, the user may toggle whether a particular

choice is selected. This action has no affect on the other menu items. Figure 11-5 shows an

example of a menu that has items and a submenu that has nonexclusive settings.

Figure 11-5. Nonexclusive settings on a submenu

In this figure, the chosen settings on the submenu are Bold and Italic. The choices not

selected are Underline and Overstrike.

11.3 Creating Menus

The header file for the MENU package is <xview/openmenu.h>, but the file is already included

by <xview/xview.h>. Another name for the MENU package is MENU_COMMAND_MENU. The

basic menu is created using xv_create():

Menu menu;

menu = (Menu)xv_create(server, MENU, NULL);

Menus (and sometimes menu items) are discrete objects that may have delayed binding. That

is, they may be created independently from any XView object and attached later using

Menus

Menus 277