VkMenuItem(3x)VkMenuItem(3x)NAMEVkMenuItem - Abstract base class for all ViewKit menu classes
INHERITS FROM
VkComponent : VkCallbackObject
HEADER FILE
#include <Vk/VkMenuItem.h>
PUBLIC PROTOCOL SUMMARY
Manipulating Menu Items
void activate();
void deactivate();
int remove();
void show();
void hide();
virtual void setLabel(const char * str);
void setPosition(int pos);
Access Functions
virtual const char* className();
virtual Boolean isContainer();
SUBCLASS PROTOCOL SUMMARY
Constructor/Destructor
VkMenuItem( );
VkMenuItem(const char * itemName);
Managing entries
static void manageAll();
CLASS DESCRIPTIONVkMenuItem is an abstract class that defines the basic behavior of all
menu objects supported by the ViewKit. There are two types of classes
derived from VkMenuItem. The first serve as containers. These correspond
to the menu types supported by Motif: popup menus, pulldown menu panes,
menubars, and option menus. The second type of derived classes can be
used as individually selectable items in a menu. These include actions,
toggles, labels, separators, and so on.
For the most part, the classes derived from VkMenuItem have a direct
correspondence to a Motif widget. An action (a VkMenuAction object)
represents an XmPushButton gadget along with an associated callback.
However, the ViewKit menus offer several advantages over directly using
Motif widgets. First, all menu items can be manipulated more easily than
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VkMenuItem(3x)VkMenuItem(3x)
widgets. All items can be displayed, activated, or deactivated with a
single function call. Items can also be moved, or replaced by other
items easily. For example an action item in a menu pane can be replaced
by a cascading pulldown menu with a single function call.
The various VkMenuItem classes also hide the somewhat confusing
organization of Motif cascade and option menus. For example, a menu pane
is just a type of menu item that can contain other items. The items in a
menu pane might include actions, toggles, labels, or other menu panes.
There are not confusing submenu id's to work with.
Menus are also constructed in the most efficient manner possible. Widgets
within a menu hierarchy are managed in groups in a completely transparent
way.
VkMenuItem is derived from VkComponent, and follows most of the
conventions associated with component. However, unlike most components,
all menu items defer the creation of widgets. When constructing menus,
objects are instantiated and organized into a hierarchy, but no widgets
are created. When the menu is to be displayed, applications must call
the build() member function for the top of the menu hierarchy. This
creates and manages all widgets at once.
Deriving Subclasses
Most common types of menu items are already defined within the ViewKit,
and it is not recommended that new classes be derived directly from
VkMenuItem. Various classes derived from VkMenuItem may be candidates
for further derivation. See the individual derived classes for more
information.
FUNCTION DESCRIPTIONS
show
void show(Widget parent);
void show();
Like most components, all menu items are displayed by calling show()
at the desired time. For VkMenuItems, show() works slightly
differently. Because the construction of the widgets associated with
menu items is delayed, show may take an argument that specifies the
parent of the menu hierarchy to be built. It is only necessary to
call show() for the top-most object in a menu hierarchy. All other
objects will be constructed automatically. The parent argument to
show() is only effective the first time it is called. Menus cannot
be reparented after they are constructed.
When called after the menu has been created or with no arguments,
show() simply sets the state of an item such that it is, or will be
visible. By default, all items will be visible when they are first
constructed. See hide() for more information.
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VkMenuItem(3x)VkMenuItem(3x)
activate
void activate();
Makes an item active so that it accepts input.
deactivate
void deactivate();
Make an item inactive so that it cannot be selected. Any item can be
active or inactive.
remove
int remove();
Removes the item from the menu hierarchy that contains it. The item
is not destroyed.
hide
void hide();
Marks an item as not visible Calling hide() on a currently visible
item unmanages the widget associated with the item. Calling hide()
for an item before the menu has been constructed marks the item so
that it will not appear when build() is called. Calling show()
reverses the effects of hide().
setLabel
virtual void setLabel(const char *str);
It is sometimes necessary to programmatically set the label of an
item. (Generally labels are retrieved from the item's
XmNlabelString resource in the resource database.) This function
allows labels to be set programmatically, without losing the ability
to set labels in the resource file. The given string is treated as
the name of a resource to be retrieved from the resource database.
If no such resource is found, the string is treated as the actual
label to be displayed.
setPosition
void setPosition(int pos);
Specify a specific position within a menu pane or menubar at which this
item should appear.
className
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VkMenuItem(3x)VkMenuItem(3x)
virtual const char* className();
The class name of this class is "VkMenuItem".
isContainer
virtual Boolean isContainer();
This function returns TRUE if an object is one of the container
types of menu items.
VkMenuItemVkMenuItem();
VkMenuItem(const char* itemName);
Initialize the data members of a VkMenuItem object.
~VkMenuItem
~VkMenuItem();
Frees all memory associated with a VkMenuItem object. If the object
is a member of a menu, the object is removed from that menu.
manageAll
static void manageAll();
INHERITED MEMBER FUNCTIONS
Inherited from VkComponent
installDestroyHandler(), removeDestroyHandler(), widgetDestroyed(),
setDefaultResources(), getResources(), manage(), unmanage(),
baseWidget(), okToQuit(), _name, _baseWidget, _w, deleteCallback
Inherited from VkCallbackObject
callCallbacks(), addCallback(), removeCallback(),
removeAllCallbacks()KNOWN DERIVED CLASSES
VkMenuAction, VkMenuConfirmFirstAction, VkMenuActionObject,
VkMenuActionWidget, VkMenuToggle, VkMenuUndoManager, VkMenuLabel,
VkMenuSeparator, VkMenu, VkOptionMenu, VkSubMenu, VkHelpPane,
VkRadioSubMenu, VkMenuBar VkPopupMenu,
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VkMenuItem(3x)VkMenuItem(3x)CLASSES USED BY THIS CLASS
VkMenu
KNOWN CLASSES THAT USE THIS CLASS
VkGraph, VkMenu, VkMenuBar, VkMenuItem, VkMenuUndoManager, VkOptionMenu,
VkPopupMenu, VkSubMenu, VkWindow
SEE ALSO
VkComponent, VkGraph, VkMenu, VkMenuBar, VkMenuUndoManager, VkOptionMenu,
VkPopupMenu, VkSubMenu, VkWindow
ViewKit Programmer's Guide
The X Window System, DEC Press, Bob Sheifler and Jim Gettys
The X Window System Toolkit, DEC Press, Paul Asente and Ralph Swick
The OSF/Motif Programmers Reference, Prentice Hall, OSF
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