MAN page from RedHat Other PerlTk-8.11-1.i386.rpm

CHECKBUTTON

Section: User Contributed Perl Documentation (1)
Updated: perl 5.004, patch 04
Index

NAME

Tk::Checkbutton - Create and manipulate Checkbutton widgets

SYNOPSIS

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

STANDARD OPTIONS

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

See the Tk::options manpage for details of the standard options.

WIDGET-SPECIFIC OPTIONS

Name: command
Class: Command
Switch: -command: Specifies a the section on Tk callback|Tk::callbacks in the perl manpage to associate with the button. This commandis typically invoked when mouse button 1 is released over the buttonwindow. The button's global variable (-variable option) willbe 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 inscreen 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 computedfrom 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 aproper boolean value. If false, the relief option isignored and the widget's relief is always sunken if the widget isselected and raised otherwise.
Name: offValue
Class: Value
Switch: -offvalue: Specifies value to store in the button's associated variable wheneverthis button is deselected. Defaults to ``0''.
Name: onValue
Class: Value
Switch: -onvalue: Specifies value to store in the button's associated variable wheneverthis 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 indicatorregardless of the select state.If indicatorOn is false, this color is used as the backgroundfor 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 fordisplaying 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 beenspecified.
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 theforeground and background options. The active state istypically used when the pointer is over the checkbutton. In active statethe checkbutton is displayed using the activeForeground andactiveBackground options. Disabled state means that the checkbuttonshould be insensitive: the default bindings will refuse to activatethe widget and will ignore mouse button presses.In this state the disabledForeground andbackground options determine how the checkbutton is displayed.
Name: variable
Class: Variable
Switch: -variable: Specifies name of global variable to set to indicate whetheror not this button is selected. Defaults to the name of thebutton within its parent (i.e. the last element of the buttonwindow's path name).
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 inscreen 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 computedfrom the size of the image or bitmap or text being displayed in it.

DESCRIPTION

The Checkbutton method creates a new window (given by the$widget argument) and makes it into a checkbutton widget.Additionaloptions, described above, may be specified on the command lineor in the option databaseto configure aspects of the checkbutton such as its colors, font,text, and initial relief. The checkbutton command returns its$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 widgetthat displays a textual string, bitmap or imageand a square called an indicator.If text is displayed, it must all be in a single font, but itcan occupy multiple lines on the screen (if it contains newlinesor if wrapping occurs because of the wrapLength option) andone of the characters may optionally be underlined using theunderline option.A checkbutton hasall of the behavior of a simple button, including thefollowing: it can display itself in either of three differentways, according to the state option;it can be made to appearraised, sunken, or flat; it can be made to flash; and it invokesa the section on Tk callback|Tk::callbacks in the perl manpage whenever mouse button 1 is clicked over thecheckbutton.

In addition, checkbuttons can be selected.If a checkbutton is selected then the indicator is normallydrawn with a selected appearance, anda Tcl variable associated with the checkbutton is set to a particularvalue (normally 1).Under Unix, the indicator is drawn with a sunken relief and a specialcolor. Under Windows, the indicator is drawn with a check mark inside.If the checkbutton is not selected, then the indicator is drawn with adeselected appearance, and the associated variable isset to a different value (typically 0).Under Unix, the indicator is drawn with a raised relief and no specialcolor. Under Windows, the indicator is drawn without a check mark inside.By default, the name of the variable associated with a checkbutton is thesame 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 optiondatabase.Configuration options may also be used to modify the way theindicator is displayed (or whether it is displayed at all).By default a checkbutton is configured to select and deselectitself on alternate button clicks.In addition, each checkbutton monitors its associated variable andautomatically selects and deselects itself when the variables valuechanges to and from the button's ``on'' value.

WIDGET METHODS

The Checkbutton method creates a widget object.This object supports the configure and cget methodsdescribed in the Tk::options manpage which can be used to enquire andmodify the options described above.The widget also inherits all the methods provided by the genericthe Tk::Widget|Tk::Widget manpage 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 checkbuttonseveral times, alternating between active and normal colors. Atthe end of the flash the checkbutton is left in the same normal/activestate 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 checkbuttonwith the mouse: toggle the selection state of the button and invokethe the section on Tk callback|Tk::callbacks in the perl manpage associated with the checkbutton, if there is one.The return value is the return value from the the section on Tk callback|Tk::callbacks in the perl manpage, or anempty 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 andmodifying its associated variable to reflect the new state.

BINDINGS

Tk automatically creates class bindings for checkbuttons that give themthe following default behavior:

[1]

On Unix systems, a checkbutton activates whenever the mouse passesover it and deactivates whenever the mouse leaves the checkbutton. OnMac and Windows systems, when mouse button 1 is pressed over acheckbutton, the button activates whenever the mouse pointer is insidethe button, and deactivates whenever the mouse pointer leaves thebutton.

[2]

When mouse button 1 is pressed over a checkbutton, it is invoked (itsselection state toggles and the command associated with the button isinvoked, if there is one).

[3]

When a checkbutton has the input focus, the space key causes the checkbuttonto 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 aboveactions occur: the checkbutton is completely non-responsive.

The behavior of checkbuttons can be changed by defining new bindings forindividual widgets or by redefining the class bindings.

KEYWORDS

checkbutton, widget

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