NAME

checkbutton - Create and manipulate checkbutton widgets

SYNOPSIS

checkbutton pathname ?options?

STANDARD OPTIONS

-activebackground -disabledcolor      -justify
-activeforeground -font               -relief
-anchor           -foreground         -takefocus
-background       -highlightcolor     -text
-bitmap           -highlightthickness -underline
-borderwidth      -image

-command command: Specifies a Tk command 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.
-height dist: Specifies a desired height for the button. 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.
-indicatoron boolean: Specifies whether or not the indicator should be drawn. If false, the relief option is ignored and the widget's relief is always sunken if the widget is selected and raised otherwise.
-offvalue string: Specifies value to store in the button's associated variable whenever this button is deselected. Defaults to ``0''.
-onvalue string: Specifies value to store in the button's associated variable whenever this button is selected. Defaults to ``1''.
-selectcolor colour: Specifies a background colour to use when the button is selected. If indicatoron is true then the colour applies to the indicator. If indicatoron is false, this colour 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 colour is used for displaying when the widget is selected.
-state 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 disabledcolor and background options determine how the checkbutton is displayed.
-variable string: Specifies name of global variable to set whenever this button is selected. Changes in this variable also cause the button to select or deselect itself.
-width dist: Specifies a desired width for the button. 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 command creates a new window (given by the pathname argument) and makes it into a checkbutton widget. Additional options, described above, may be specified on the command line to configure aspects of the checkbutton such as its colours, font, text, and initial relief. The checkbutton command returns its pathname argument. At the time this command is invoked, there must not exist a window named pathname.

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) and one of the characters may optionally be underlined using the underline option. A checkbutton has all of the behaviour 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; and it invokes a Tk command 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 sunken relief and a tick (check) mark, and a Tk variable associated with the checkbutton is set to the onvalue (normally 1). If the checkbutton is not selected, then the indicator is drawn as an empty box with raised relief, and the associated variable is set to the offvalue (normally 0). The variable name may be modified with options on the command line (-variable option). 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.

WIDGET COMMAND

The checkbutton command creates a new Tk command whose name is pathname. This command may be used to invoke various operations on the widget. It has the following general form:

pathname option ?arg arg ...?

Option and the args determine the exact behaviour of the command. The following commands are possible for checkbutton widgets:

pathname cget option: Returns the current value of the configuration option given by option. Option may have any of the values accepted by the checkbutton command.
pathname configure ?option? ?value option value ...?: Query or modify the configuration options of the widget. If no option is specified, returns a list of all of the available options for pathname. If one or more option-value pairs are specified, then the command modifies the given widget option(s) to have the given value(s); in this case the command returns an empty string. Option may have any of the values accepted by the checkbutton command.
pathname deselect: Deselects the checkbutton and sets the associated variable to its ``off'' value.
pathname 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 Tk command associated with the checkbutton, if there is one. The return value is the return value from the Tk command, or an empty string if there is no command associated with the checkbutton. This command is ignored if the checkbutton's state is disabled.
pathname select: Selects the checkbutton and sets the associated variable to 1.
pathname toggle: Toggles the selection state of the button, redisplaying it and modifying its associated variable to reflect the new state.

BINDINGS

Tk automatically creates bindings for checkbuttons that give them the following default behaviour:

[1]: A checkbutton activates whenever the mouse passes over it and deactivates whenever the mouse leaves the checkbutton.
[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).

If the checkbutton's state is disabled then none of the above actions occur: the checkbutton is completely non-responsive.

The behaviour of checkbuttons can be changed by defining new bindings for individual widgets.