Menu(3) User Contributed Perl Documentation Menu(3)NAMETk::Menu - Create and manipulate Menu widgets
SYNOPSIS
$menu = $parent->Menu(?options?);
STANDARD OPTIONS-activebackground-background-disabledforeground -relief
-activeborderwidth-borderwidth-font-takefocus
-activeforeground-cursor-foreground
See Tk::options for details of the standard options.
WIDGET-SPECIFIC OPTIONS
Name: postCommand
Class: Command
Switch: -postcommand
If this option is specified then it provides a callback to execute
each time the menu is posted. The callback is invoked by the post
method before posting the menu. Note that in 8.0 on Macintosh and
Windows, all commands in a menu systems are executed before any are
posted. This is due to the limitations in the individual platforms'
menu managers.
Name: selectColor
Class: Background
Switch: -selectcolor
For menu entries that are check buttons or radio buttons, this
option specifies the color to display in the indicator when the
check button or radio button is selected.
Name: tearOff
Class: TearOff
Switch: -tearoff
This option must have a proper boolean value, which specifies
whether or not the menu should include a tear-off entry at the top.
If so, it will exist as entry 0 of the menu and the other entries
will number starting at 1. The default menu bindings arrange for
the menu to be torn off when the tear-off entry is invoked.
Name: tearOffCommand
Class: TearOffCommand
Switch: -tearoffcommand
If this option has a non-empty value, then it specifies a perl/Tk
callback to invoke whenever the menu is torn off. The actual
command will consist of the value of this option, followed by a
space, followed by the name of the menu window, followed by a
space, followed by the name of the name of the torn off menu
window. For example, if the option's is ``a b'' and menu .x.y is
torn off to create a new menu .x.tearoff1, then the command ``a b
.x.y .x.tearoff1'' will be invoked.
Name: title
Class: Title
Switch: -title
The string will be used to title the window created when this menu
is torn off. If the title is NULL, then the window will have the
title of the menubutton or the text of the cascade item from which
this menu was invoked.
Name: type
Class: Type
Switch: -type
This option can be one of menubar, tearoff, or normal, and is set
when the menu is created. While the string returned by the
configuration database will change if this option is changed, this
does not affect the menu widget's behavior. This is used by the
cloning mechanism and is not normally set outside of the Tk
library.
DESCRIPTION
The Menu method creates a new top-level window (given by the $widget
argument) and makes it into a menu widget. Additional options,
described above, may be specified on the command line or in the option
database to configure aspects of the menu such as its colors and font.
The menu command returns its $widget argument. At the time this
command is invoked, there must not exist a window named $widget, but
$widget's parent must exist.
A menu is a widget that displays a collection of one-line entries
arranged in one or more columns. There exist several different types
of entries, each with different properties. Entries of different types
may be combined in a single menu. Menu entries are not the same as
entry widgets. In fact, menu entries are not even distinct widgets;
the entire menu is one widget.
Menu entries are displayed with up to three separate fields. The main
field is a label in the form of a text string, a bitmap, or an image,
controlled by the -label, -bitmap, and -image options for the entry.
If the -accelerator option is specified for an entry then a second
textual field is displayed to the right of the label. The accelerator
typically describes a keystroke sequence that may be typed in the
application to cause the same result as invoking the menu entry. The
third field is an indicator. The indicator is present only for
checkbutton or radiobutton entries. It indicates whether the entry is
selected or not, and is displayed to the left of the entry's string.
In normal use, an entry becomes active (displays itself differently)
whenever the mouse pointer is over the entry. If a mouse button is
released over the entry then the entry is invoked. The effect of
invocation is different for each type of entry; these effects are
described below in the sections on individual entries.
Entries may be disabled, which causes their labels and accelerators to
be displayed with dimmer colors. The default menu bindings will not
allow a disabled entry to be activated or invoked. Disabled entries
may be re-enabled, at which point it becomes possible to activate and
invoke them again.
Whenever a menu's active entry is changed, a <<MenuSelect>> virtual
event is sent to the menu. The active item can then be queried from the
menu, and an action can be taken, such as setting context-sensitive
help text for the entry.
COMMAND ENTRIES
The most common kind of menu entry is a command entry, which behaves
much like a button widget. When a command entry is invoked, a callback
is executed. The callback is specified with the -command option.
SEPARATOR ENTRIES
A separator is an entry that is displayed as a horizontal dividing
line. A separator may not be activated or invoked, and it has no
behavior other than its display appearance.
CHECKBUTTON ENTRIES
A checkbutton menu entry behaves much like a checkbutton widget. When
it is invoked it toggles back and forth between the selected and
deselected states. When the entry is selected, a particular value is
stored in a particular global variable (as determined by the -onvalue
and -variable options for the entry); when the entry is deselected
another value (determined by the -offvalue option) is stored in the
global variable. An indicator box is displayed to the left of the
label in a checkbutton entry. If the entry is selected then the
indicator's center is displayed in the color given by the -selectcolor
option for the entry; otherwise the indicator's center is displayed in
the background color for the menu. If a -command option is specified
for a checkbutton entry, then its value is evaluated each time the
entry is invoked; this happens after toggling the entry's selected
state.
RADIOBUTTON ENTRIES
A radiobutton menu entry behaves much like a radiobutton widget.
Radiobutton entries are organized in groups of which only one entry may
be selected at a time. Whenever a particular entry becomes selected it
stores a particular value into a particular global variable (as
determined by the -value and -variable options for the entry). This
action causes any previously-selected entry in the same group to
deselect itself. Once an entry has become selected, any change to the
entry's associated variable will cause the entry to deselect itself.
Grouping of radiobutton entries is determined by their associated
variables: if two entries have the same associated variable then they
are in the same group. An indicator diamond is displayed to the left
of the label in each radiobutton entry. If the entry is selected then
the indicator's center is displayed in the color given by the
-selectcolor option for the entry; otherwise the indicator's center is
displayed in the background color for the menu. If a -command option
is specified for a radiobutton entry, then its value is evaluated each
time the entry is invoked; this happens after selecting the entry.
CASCADE ENTRIES
A cascade entry is one with an associated menu (determined by the -menu
option). Cascade entries allow the construction of cascading menus.
The postcascade method can be used to post and unpost the associated
menu just next to of the cascade entry. The associated menu must be a
child of the menu containing the cascade entry (this is needed in order
for menu traversal to work correctly).
A cascade entry posts its associated menu by invoking
$menu->post(x,y)
where menu is the path name of the associated menu, and x and y are the
root-window coordinates of the upper-right corner of the cascade entry.
On Unix, the lower-level menu is unposted by executing
$menu->unpost
where menu is the name of the associated menu. On other platforms, the
platform's native code takes care of unposting the menu.
If a -command option is specified for a cascade entry then it is
evaluated whenever the entry is invoked. This is not supported on
Windows.
TEAR-OFF ENTRIES
A tear-off entry appears at the top of the menu if enabled with the
tearOff option. It is not like other menu entries in that it cannot be
created with the add method and cannot be deleted with the delete
method. When a tear-off entry is created it appears as a dashed line
at the top of the menu. Under the default bindings, invoking the tear-
off entry causes a torn-off copy to be made of the menu and all of its
submenus.
MENUBARS
Any menu can be set as a menubar for a toplevel window (see the
Toplevel constructor for syntax). On the Macintosh, whenever the
toplevel is in front, this menu's cascade items will appear in the
menubar across the top of the main monitor. On Windows and Unix, this
menu's items will be displayed in a menubar accross the top of the
window. These menus will behave according to the interface guidelines
of their platforms. For every menu set as a menubar, a clone menu is
made. See "CLONES" for more information.
As noted, menubars may behave differently on different platforms. One
example of this concerns the handling of checkbuttons and radiobuttons
within the menu. While it is permitted to put these menu elements on
menubars, they may not be drawn with indicators on some platforms, due
to system restrictions.
SPECIAL MENUS IN MENUBARS
Certain menus in a menubar will be treated specially. On the
Macintosh, access to the special Apple and Help menus is provided. On
Windows, access to the Windows System menu in each window is provided.
On X Windows, a special right-justified help menu is provided. In all
cases, these menus must be created with the command name of the menubar
menu concatenated with the special name. So for a menubar named
.menubar, on the Macintosh, the special menus would be .menubar.apple
and .menubar.help; on Windows, the special menu would be
.menubar.system; on X Windows, the help menu would be .menubar.help.
When Tk sees an Apple menu on the Macintosh, that menu's contents make
up the first items of the Apple menu on the screen whenever the window
containing the menubar is in front. The menu is the first one that the
user sees and has a title which is an Apple logo. After all of the Tk-
defined items, the menu will have a separator, followed by all of the
items in the user's Apple Menu Items folder. Since the System uses a
different menu definition procedure for the Apple menu than Tk uses for
its menus, and the system APIs do not fully support everything Tk tries
to do, the menu item will only have its text displayed. No font
attributes, images, bitmaps, or colors will be displayed. In addition,
a menu with a tearoff item will have the tearoff item displayed as
"(TearOff)".
When Tk see a Help menu on the Macintosh, the menu's contents are
appended to the standard help menu on the right of the user's menubar
whenever the user's menubar is in front. The first items in the menu
are provided by Apple. Similar to the Apple Menu, cusomization in this
menu is limited to what the system provides.
When Tk sees a System menu on Windows, its items are appended to the
system menu that the menubar is attached to. This menu has an icon
representing a spacebar, and can be invoked with the mouse or by typing
Alt+Spacebar. Due to limitations in the Windows API, any font changes,
colors, images, bitmaps, or tearoff images will not appear in the
system menu.
When Tk see a Help menu on X Windows, the menu is moved to be last in
the menubar and is right justified.
CLONES
When a menu is set as a menubar for a toplevel window, or when a menu
is torn off, a clone of the menu is made. This clone is a menu widget
in its own right, but it is a child of the original. Changes in the
configuration of the original are reflected in the clone. Additionally,
any cascades that are pointed to are also cloned so that menu traversal
will work right. Clones are destroyed when either the tearoff or
menubar goes away, or when the original menu is destroyed.
WIDGET METHODS
The Menu method creates a widget object. This object supports the
configure and cget methods described in Tk::options which can be used
to enquire and modify the options described above. The widget also
inherits all the methods provided by the generic Tk::Widget class, and
the Tk::Wm class.
Many of the methods for a menu take as one argument an indicator of
which entry of the menu to operate on. These indicators are called
indexes and may be specified in any of the following forms:
number
Specifies the entry numerically, where 0 corresponds to the top-
most entry of the menu, 1 to the entry below it, and so on.
active
Indicates the entry that is currently active. If no entry is
active then this form is equivalent to none. This form may not be
abbreviated.
end Indicates the bottommost entry in the menu. If there are no
entries in the menu then this form is equivalent to none. This
form may not be abbreviated.
last
Same as end.
none
Indicates ``no entry at all''; this is used most commonly with the
activate option to deactivate all the entries in the menu. In most
cases the specification of none causes nothing to happen in the
method. This form may not be abbreviated.
@number
In this form, number is treated as a y-coordinate in the menu's
window; the entry closest to that y-coordinate is used. For
example, ``@0'' indicates the top-most entry in the window.
pattern
If the index doesn't satisfy one of the above forms then this form
is used. Pattern is pattern-matched against the label of each
entry in the menu, in order from the top down, until a matching
entry is found. (In perl/Tk the matching is under review, but
exact match should work.)
The following methods are possible for menu widgets:
$menu->activate(index)
Change the state of the entry indicated by index to active and
redisplay it using its active colors. Any previously-active entry
is deactivated. If index is specified as none, or if the specified
entry is disabled, then the menu ends up with no active entry.
Returns an empty string.
$menu->add(type, ?option, value, option, value, ...?)
Add a new entry to the bottom of the menu. The new entry's type is
given by type and must be one of cascade, checkbutton, command,
radiobutton, or separator, or a unique abbreviation of one of the
above. If additional arguments are present, they specify any of
the following options:
-activebackground => value
Specifies a background color to use for displaying this
entry when it is active. If this option is specified as an
empty string (the default), then the activeBackground
option for the overall menu is used. If the
$Tk::strictMotif variable has been set to request strict
Motif compliance, then this option is ignored and the
-background option is used in its place. This option is
not available for separator or tear-off entries.
-activeforeground => value
Specifies a foreground color to use for displaying this
entry when it is active. If this option is specified as an
empty string (the default), then the activeForeground
option for the overall menu is used. This option is not
available for separator or tear-off entries.
-accelerator => value
Specifies a string to display at the right side of the menu
entry. Normally describes an accelerator keystroke
sequence that may be typed to invoke the same function as
the menu entry. This option is not available for separator
or tear-off entries.
-background => value
Specifies a background color to use for displaying this
entry when it is in the normal state (neither active nor
disabled). If this option is specified as an empty string
(the default), then the background option for the overall
menu is used. This option is not available for separator
or tear-off entries.
-bitmap => value
Specifies a bitmap to display in the menu instead of a
textual label, in any of the forms accepted by
Tk_GetBitmap. This option overrides the -label option but
may be reset to an empty string to enable a textual label
to be displayed. If a -image option has been specified, it
overrides -bitmap. This option is not available for
separator or tear-off entries.
-columnbreak => value
When this option is zero, the appears below the previous
entry. When this option is one, the menu appears at the top
of a new column in the menu.
-compound => value
Specifies whether the button should display both an image
and text, and if so, where the image should be placed
relative to the text. Valid values for this option are
bottom, center, left, none, right and top. The default
value is none, meaning that the button will display either
an image or text, depending on the values of the -image and
-bitmap options.
-command => value
For command, checkbutton, and radiobutton entries,
specifies a callback to execute when the menu entry is
invoked. For cascade entries, specifies a callback to
execute when the entry is activated (i.e. just before its
submenu is posted). Not available for separator or tear-
off entries.
-font => value
Specifies the font to use when drawing the label or
accelerator string in this entry. If this option is
specified as an empty string (the default) then the font
option for the overall menu is used. This option is not
available for separator or tear-off entries.
-foreground => value
Specifies a foreground color to use for displaying this
entry when it is in the normal state (neither active nor
disabled). If this option is specified as an empty string
(the default), then the foreground option for the overall
menu is used. This option is not available for separator
or tear-off entries.
-hidemargin => value
Specifies whether the standard margins should be drawn for
this menu entry. This is useful when creating palette with
images in them, i.e., color palettes, pattern palettes,
etc. 1 indicates that the margin for the entry is hidden; 0
means that the margin is used.
-image => value
Specifies an image to display in the menu instead of a text
string or bitmap The image must have been created by some
previous invocation of image create. This option overrides
the -label and -bitmap options but may be reset to an empty
string to enable a textual or bitmap label to be displayed.
This option is not available for separator or tear-off
entries.
-indicatoron => value
Available only for checkbutton and radiobutton entries.
Value is a boolean that determines whether or not the
indicator should be displayed.
-label => value
Specifies a string to display as an identifying label in
the menu entry. Not available for separator or tear-off
entries.
-menu => value
Available only for cascade entries. Specifies the path
name of the submenu associated with this entry. The
submenu must be a child of the menu.
-offvalue => value
Available only for checkbutton entries. Specifies the
value to store in the entry's associated variable when the
entry is deselected.
-onvalue => value
Available only for checkbutton entries. Specifies the
value to store in the entry's associated variable when the
entry is selected.
-selectcolor => value
Available only for checkbutton and radiobutton entries.
Specifies the color to display in the indicator when the
entry is selected. If the value is an empty string (the
default) then the selectColor option for the menu
determines the indicator color.
-selectimage => value
Available only for checkbutton and radiobutton entries.
Specifies an image to display in the entry (in place of the
-image option) when it is selected. Value is the name of
an image, which must have been created by some previous
invocation of image create. This option is ignored unless
the -image option has been specified.
-state => value
Specifies one of three states for the entry: normal,
active, or disabled. In normal state the entry is
displayed using the foreground option for the menu and the
background option from the entry or the menu. The active
state is typically used when the pointer is over the entry.
In active state the entry is displayed using the
activeForeground option for the menu along with the
activebackground option from the entry. Disabled state
means that the entry should be insensitive: the default
bindings will refuse to activate or invoke the entry. In
this state the entry is displayed according to the
disabledForeground option for the menu and the background
option from the entry. This option is not available for
separator entries.
-underline => value
Specifies the integer index of a character to underline in
the entry. This option is also queried by the default
bindings and used to implement keyboard traversal. 0
corresponds to the first character of the text displayed in
the entry, 1 to the next character, and so on. If a bitmap
or image is displayed in the entry then this option is
ignored. This option is not available for separator or
tear-off entries.
-value => value
Available only for radiobutton entries. Specifies the
value to store in the entry's associated variable when the
entry is selected. If an empty string is specified, then
the -label option for the entry as the value to store in
the variable.
-variable => value
Available only for checkbutton and radiobutton entries.
Specifies the name of a global value to set when the entry
is selected. For checkbutton entries the variable is also
set when the entry is deselected. For radiobutton entries,
changing the variable causes the currently-selected entry
to deselect itself.
The add method returns an empty string.
$menu->clone($parent ?, cloneType?)
Makes a clone of the current menu as a child of $parent. This clone
is a menu in its own right, but any changes to the clone are
propogated to the original menu and vice versa. cloneType can be
normal, menubar, or tearoff. Should not normally be called outside
of the Tk library. See "CLONES" for more information.
$menu->delete(index1?, index2?)
Delete all of the menu entries between index1 and index2 inclusive.
If index2 is omitted then it defaults to index1. Attempts to
delete a tear-off menu entry are ignored (instead, you should
change the tearOff option to remove the tear-off entry).
$menu->entrycget(index, option)
Returns the current value of a configuration option for the entry
given by index. Option may have any of the values accepted by the
add method.
$menu->entryconfigure(index ?,options?)
This method is similar to the configure method, except that it
applies to the options for an individual entry, whereas configure
applies to the options for the menu as a whole. Options may have
any of the values accepted by the add method. If options are
specified, options are modified as indicated in the method call and
the method returns an empty string. If no options are specified,
returns a list describing the current options for entry index (see
Tk::options for information on the format of this list).
$menu->index(index)
Returns the numerical index corresponding to index, or none if
index was specified as none.
$menu->insert(index, type?, -option=>value, ...?)
Same as the add method except that it inserts the new entry just
before the entry given by index, instead of appending to the end of
the menu. The type, -option, and value arguments have the same
interpretation as for the add widget method. It is not possible to
insert new menu entries before the tear-off entry, if the menu has
one.
$menu->invoke(index)
Invoke the action of the menu entry. See the sections on the
individual entries above for details on what happens. If the menu
entry is disabled then nothing happens. If the entry has a
callback associated with it then the result of that callback is
returned as the result of the invoke widget method. Otherwise the
result is an empty string. Note: invoking a menu entry does not
automatically unpost the menu; the default bindings normally take
care of this before invoking the invoke method.
$menu->post(x, y)
Arrange for the menu to be displayed on the screen at the root-
window coordinates given by x and y. These coordinates are
adjusted if necessary to guarantee that the entire menu is visible
on the screen. This method normally returns an empty string. If
the postCommand option has been specified, then its value is
executed before posting the menu and the result of that callback is
returned as the result of the post widget method. If an error
returns while executing the method, then the error is returned
without posting the menu.
$menu->postcascade(index)
Posts the submenu associated with the cascade entry given by index,
and unposts any previously posted submenu. If index doesn't
correspond to a cascade entry, or if $menu isn't posted, the method
has no effect except to unpost any currently posted submenu.
$menu->type(index)
Returns the type of the menu entry given by index. This is the
type argument passed to the add widget method when the entry was
created, such as command or separator, or tearoff for a tear-off
entry.
$menu->unpost
Unmap the window so that it is no longer displayed. If a lower-
level cascaded menu is posted, unpost that menu. Returns an empty
string. This method does not work on Windows and the Macintosh, as
those platforms have their own way of unposting menus.
$menu->yposition(index)
Returns a decimal string giving the y-coordinate within the menu
window of the topmost pixel in the entry specified by index.
MENU CONFIGURATIONS
The default bindings support four different ways of using menus:
Pulldown Menus in Menubar
This is the most command case. You create a menu widget that will
become the menu bar. You then add cascade entries to this menu,
specifying the pull down menus you wish to use in your menu bar.
You then create all of the pulldowns. Once you have done this,
specify the menu using the -menu option of the toplevel's method.
See the toplevel manual entry for details.
Pulldown Menus in Menu Buttons
This is the compatable way to do menu bars. You create one
menubutton widget for each top-level menu, and typically you
arrange a series of menubuttons in a row in a menubar window. You
also create the top-level menus and any cascaded submenus, and tie
them together with -menu options in menubuttons and cascade menu
entries. The top-level menu must be a child of the menubutton, and
each submenu must be a child of the menu that refers to it. Once
you have done this, the default bindings will allow users to
traverse and invoke the tree of menus via its menubutton; see the
menubutton documentation for details.
Popup Menus
Popup menus typically post in response to a mouse button press or
keystroke. You create the popup menus and any cascaded submenus,
then you call the Post method at the appropriate time to post the
top-level menu.
$menu->Post($x,$y?,$entry?)
$x and $y are the root window coordinates at which the $menu will
be displayed. If $entry is specified then that entry is centred on
that point, otherwise the top-left corner of the $menu is placed at
that point.
Menu also inherits methods from Tk::Wm and so the method Popup can
be used to position menu relative to other windows, the mouse
cursor or the screen.
Option Menus
An option menu consists of a menubutton with an associated menu
that allows you to select one of several values. The current value
is displayed in the menubutton and is also stored in a global
variable. Use the Tk::Optionmenu class to create option
menubuttons and their menus.
Torn-off Menus
You create a torn-off menu by invoking the tear-off entry at the
top of an existing menu. The default bindings will create a new
menu that is a copy of the original menu and leave it permanently
posted as a top-level window. The torn-off menu behaves just the
same as the original menu.
DEFAULT BINDINGS
Tk automatically creates class bindings for menus that give them the
following default behavior:
[1] When the mouse enters a menu, the entry underneath the mouse cursor
activates; as the mouse moves around the menu, the active entry
changes to track the mouse.
[2] When the mouse leaves a menu all of the entries in the menu
deactivate, except in the special case where the mouse moves from a
menu to a cascaded submenu.
[3] When a button is released over a menu, the active entry (if any) is
invoked. The menu also unposts unless it is a torn-off menu.
[4] The Space and Return keys invoke the active entry and unpost the
menu.
[5] If any of the entries in a menu have letters underlined with with
-underline option, then pressing one of the underlined letters (or
its upper-case or lower-case equivalent) invokes that entry and
unposts the menu.
[6] The Escape key aborts a menu selection in progress without invoking
any entry. It also unposts the menu unless it is a torn-off menu.
[7] The Up and Down keys activate the next higher or lower entry in the
menu. When one end of the menu is reached, the active entry wraps
around to the other end.
[8] The Left key moves to the next menu to the left. If the current
menu is a cascaded submenu, then the submenu is unposted and the
current menu entry becomes the cascade entry in the parent. If the
current menu is a top-level menu posted from a menubutton, then the
current menubutton is unposted and the next menubutton to the left
is posted. Otherwise the key has no effect. The left-right order
of menubuttons is determined by their stacking order: Tk assumes
that the lowest menubutton (which by default is the first one
created) is on the left.
[9] The Right key moves to the next menu to the right. If the current
entry is a cascade entry, then the submenu is posted and the
current menu entry becomes the first entry in the submenu.
Otherwise, if the current menu was posted from a menubutton, then
the current menubutton is unposted and the next menubutton to the
right is posted.
Disabled menu entries are non-responsive: they don't activate and
they ignore mouse button presses and releases.
The behavior of menus can be changed by defining new bindings for
individual widgets or by redefining the class bindings.
BUGS
At present it isn't possible to use the option database to specify
values for the options to individual entries.
SEE ALSO
Tk::callbacks
KEYWORDS
menu, widget
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 72:
alternative text 'perl/Tk callback' contains non-escaped | or /
perl v5.18.1 2013-10-19 Menu(3)
