NAME

       Tk::Checkbutton - Create and manipulate Checkbutton widgets

SYNOPSIS

       $checkbutton = $parent->Checkbutton(?options?);

STANDARD OPTIONS

       -activebackground -activeforeground -anchor -background -bitmap -borderwidth -compound
       -cursor -disabledforeground -font -foreground -highlightbackground -highlightcolor
       -highlightthickness -image -justify -padx -pady -relief -takefocus -text -textvariable
       -underline -wraplength

       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 -overrelief 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 Underline 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 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''.

       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 button.  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 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.  Disabled 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 "\$widget->{'Value'}" member of the widget's hash. In general
           perl variables are "undef" unless specifically initialized which will not match either
           default -onvalue 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 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 newlines or if wrapping occurs because
       of the wrapLength option) and one of the characters may optionally be underlined using the
       underline option.  A checkbutton has all of the behavior 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 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 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 configured to select and
       deselect itself on alternate button clicks.  In addition, each checkbutton monitors its
       associated variable and automatically 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 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 variable to its ``on'' value.

       $checkbutton->toggle
           Toggles the selection state of the button, redisplaying 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 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 bindings for individual
           widgets or by redefining the class bindings.

KEYWORDS

       checkbutton, widget