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Menu(3) |
User Contributed Perl Documentation |
Menu(3) |
Tk::Menu - Create and manipulate Menu widgets
$menu =
$parent ->Menu(?options?);
-activebackground -background -disabledforeground -relief
-activeborderwidth -borderwidth -font -takefocus
-activeforeground -cursor -foreground
See Tk::options for details of the standard 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
At present it isn't possible to use the option database to specify values for
the options to individual entries.
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