Checkbutton(3) User Contributed Perl Documentation Checkbutton(3)NAMETk::Checkbutton - Create and manipulate Checkbutton widgets
SYNOPSIS
$checkbutton = $parent->Checkbutton(?options?);
STANDARD OPTIONS-activebackground-cursor-highlightthickness -takefocus -active‐
foreground -disabledforeground -image -text
-anchor-font-justify-textvariable -background -fore‐
ground -padx-underline -bitmap -highlightback‐
ground -pady-wraplength -borderwidth -highlight‐
color -relief
See Tk::options for details of the standard options.
WIDGET-SPECIFIC OPTIONS
Name: command
Class: Command
Switch: -command
Specifies a perl/Tk callback to associate with the button. This
command is typically invoked when mouse button 1 is released over
the button window. The button's global variable (-variable option)
will be updated before the command is invoked.
Name: height
Class: Height
Switch: -height
Specifies a desired height for the button. If an image or bitmap
is being displayed in the button then the value is in screen units
(i.e. any of the forms acceptable to Tk_GetPixels); for text it is
in lines of text. If this option isn't specified, the button's
desired height is computed from the size of the image or bitmap or
text being displayed in it.
Name: indicatorOn
Class: IndicatorOn
Switch: -indicatoron
Specifies whether or not the indicator should be drawn. Must be a
proper boolean value. If false, the relief option is ignored and
the widget's relief is always sunken if the widget is selected and
raised otherwise.
Command-Line Name: -offrelief
Database Name: offRelief
Database Class: OffRelief
Specifies the relief for the checkbutton when the indicator is not
drawn and the checkbutton is off. The default value is raised. By
setting this option to flat and setting -indicatoron false -overre‐
lief raised, the effect is achieved of having a flat button that
raises on mouse-over and which is depressed when activated. This
is the behavior typically exhibited by the Bold, Italic, and Under‐
line checkbuttons on the toolbar of a word-processor, for example.
Name: offValue
Class: Value
Switch: -offvalue
Specifies value to store in the button's associated variable when‐
ever this button is deselected. Defaults to ``0''.
Name: onValue
Class: Value
Switch: -onvalue
Specifies value to store in the button's associated variable when‐
ever this button is selected. Defaults to ``1''.
Command-Line Name: -overrelief
Database Name: overRelief
Database Class: OverRelief
Specifies an alternative relief for the button, to be used when
the mouse cursor is over the widget. This option can be used to
make toolbar buttons, by configuring -relief flat -overrelief
raised. If the value of this option is the empty string, then no
alternative relief is used when the mouse cursor is over the but‐
ton. The empty string is the default value.
Name: selectColor
Class: Background
Switch: -selectcolor
Specifies a background color to use when the button is selected.
If indicatorOn is true then the color applies to the indicator.
Under Windows, this color is used as the background for the indica‐
tor regardless of the select state. If indicatorOn is false, this
color is used as the background for the entire widget, in place of
background or activeBackground, whenever the widget is selected.
If specified as an empty string then no special color is used for
displaying when the widget is selected.
Name: selectImage
Class: SelectImage
Switch: -selectimage
Specifies an image to display (in place of the image option) when
the checkbutton is selected. This option is ignored unless the
image option has been specified.
Name: state
Class: State
Switch: -state
Specifies one of three states for the checkbutton: normal, active,
or disabled. In normal state the checkbutton is displayed using
the foreground and background options. The active state is typi‐
cally used when the pointer is over the checkbutton. In active
state the checkbutton is displayed using the activeForeground and
activeBackground options. Disabled state means that the checkbut‐
ton should be insensitive: the default bindings will refuse to
activate the widget and will ignore mouse button presses. In this
state the disabledForeground and background options determine how
the checkbutton is displayed.
Name: variable
Class: Variable
Switch: -variable
Specifies reference to a variable to set to indicate whether or not
this button is selected. Defaults to "\$widget->{'Value'}" member
of the widget's hash. In general perl variables are "undef" unless
specifically initialized which will not match either default -onva‐
lue or default -offvalue.
Name: width
Class: Width
Switch: -width
Specifies a desired width for the button. If an image or bitmap is
being displayed in the button then the value is in screen units
(i.e. any of the forms acceptable to Tk_GetPixels); for text it is
in characters. If this option isn't specified, the button's
desired width is computed from the size of the image or bitmap or
text being displayed in it.
DESCRIPTION
The Checkbutton method creates a new window (given by the $widget argu‐
ment) and makes it into a checkbutton widget. Additional options,
described above, may be specified on the command line or in the option
database to configure aspects of the checkbutton such as its colors,
font, text, and initial relief. The checkbutton 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 checkbutton is a widget that displays a textual string, bitmap or
image and a square called an indicator. If text is displayed, it must
all be in a single font, but it can occupy multiple lines on the screen
(if it contains newlines or if wrapping occurs because of the
wrapLength option) and one of the characters may optionally be under‐
lined using the underline option. A checkbutton has all of the behav‐
ior of a simple button, including the following: it can display itself
in either of three different ways, according to the state option; it
can be made to appear raised, sunken, or flat; it can be made to flash;
and it invokes a perl/Tk callback whenever mouse button 1 is clicked
over the checkbutton.
In addition, checkbuttons can be selected. If a checkbutton is
selected then the indicator is normally drawn with a selected appear‐
ance, and a Tcl variable associated with the checkbutton is set to a
particular value (normally 1). Under Unix, the indicator is drawn with
a sunken relief and a special color. Under Windows, the indicator is
drawn with a check mark inside. If the checkbutton is not selected,
then the indicator is drawn with a deselected appearance, and the asso‐
ciated variable is set to a different value (typically 0). Under Unix,
the indicator is drawn with a raised relief and no special color.
Under Windows, the indicator is drawn without a check mark inside. By
default, the name of the variable associated with a checkbutton is the
same as the name used to create the checkbutton. The variable name,
and the ``on'' and ``off'' values stored in it, may be modified with
options on the command line or in the option database. Configuration
options may also be used to modify the way the indicator is displayed
(or whether it is displayed at all). By default a checkbutton is con‐
figured to select and deselect itself on alternate button clicks. In
addition, each checkbutton monitors its associated variable and auto‐
matically selects and deselects itself when the variables value changes
to and from the button's ``on'' value.
WIDGET METHODS
The Checkbutton 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.
The following additional methods are available for checkbutton widgets:
$checkbutton->deselect
Deselects the checkbutton and sets the associated variable to its
``off'' value.
$checkbutton->flash
Flashes the checkbutton. This is accomplished by redisplaying the
checkbutton several times, alternating between active and normal
colors. At the end of the flash the checkbutton is left in the
same normal/active state as when the command was invoked. This
command is ignored if the checkbutton's state is disabled.
$checkbutton->invoke
Does just what would have happened if the user invoked the check‐
button with the mouse: toggle the selection state of the button and
invoke the perl/Tk callback associated with the checkbutton, if
there is one. The return value is the return value from the
perl/Tk callback, or an empty string if there is no command associ‐
ated with the checkbutton. This command is ignored if the check‐
button's state is disabled.
$checkbutton->select
Selects the checkbutton and sets the associated variable to its
``on'' value.
$checkbutton->toggle
Toggles the selection state of the button, redisplaying it and mod‐
ifying its associated variable to reflect the new state.
BINDINGS
Tk automatically creates class bindings for checkbuttons that give them
the following default behavior:
[1] On Unix systems, a checkbutton activates whenever the mouse passes
over it and deactivates whenever the mouse leaves the checkbutton.
On Mac and Windows systems, when mouse button 1 is pressed over a
checkbutton, the button activates whenever the mouse pointer is
inside the button, and deactivates whenever the mouse pointer
leaves the button.
[2] When mouse button 1 is pressed over a checkbutton, it is invoked
(its selection state toggles and the command associated with the
button is invoked, if there is one).
[3] When a checkbutton has the input focus, the space key causes the
checkbutton to be invoked. Under Windows, there are additional key
bindings; plus (+) and equal (=) select the button, and minus (-)
deselects the button.
If the checkbutton's state is disabled then none of the above
actions occur: the checkbutton is completely non-responsive.
The behavior of checkbuttons can be changed by defining new bind‐
ings for individual widgets or by redefining the class bindings.
KEYWORDS
checkbutton, widget
perl v5.8.8 2004-02-28 Checkbutton(3)
