checkbutton(3)
NAME
Tk::Checkbutton - Create and manipulate Checkbutton wid
gets
SYNOPSIS
$checkbutton = $parent->Checkbutton(?options?);
STANDARD OPTIONS
-activebackground -cursor -highlightthickness -takefo
cus -activeforeground -disabledfore
ground -image -text -anchor -font -jus
tify -textvariable -background -fore
ground -padx -underline -bitmap -highlightback
ground -pady -wraplength -borderwidth -high
lightcolor -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 but
ton'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. - Name: offValue
Class: Value
Switch: -offvalue - Specifies value to store in the button's associated
variable whenever this button is deselected. Defaults
to ``0''. - Name: onValue
Class: Value
Switch: -onvalue - Specifies value to store in the button's associated
variable whenever this button is selected. Defaults
to ``1''. - 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 indicator 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 typically used when the pointer is over the checkbutton. In
active state the checkbutton is displayed using the
activeForeground and activeBackground options. Dis abled state means that the checkbutton 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
"idget->{'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 charac ters. 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 argument) 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 new
lines 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 behavior of a simple button, including the follow
ing: 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 checkbut
ton is selected then the indicator is normally drawn with
a selected appearance, 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 associated variable is set to a dif
ferent 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. Configura
tion options may also be used to modify the way the indi
cator is displayed (or whether it is displayed at all).
By default a checkbutton is configured to select and dese
lect itself on alternate button clicks. In addition, each
checkbutton monitors its associated variable and automati
cally 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 check
button 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, alternat
ing between active and normal colors. At the end of
the flash the checkbutton is left in the same nor
mal/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 checkbutton 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
associated with the checkbutton. This command is
ignored if the checkbutton's state is disabled. - $checkbutton->select
- Selects the checkbutton and sets the associated vari
able to its ``on'' value. - $checkbutton->toggle
- Toggles the selection state of the button, redisplay
ing it and modifying 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 sys
tems, when mouse button 1 is pressed over a checkbut
ton, 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 com
mand 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 com
pletely non-responsive. - The behavior of checkbuttons can be changed by defin
ing new bindings for individual widgets or by redefin
ing the class bindings.
KEYWORDS
- checkbutton, widget