Radiobutton(3)

NAME
Tk::Radiobutton - Create and manipulate Radiobutton widgets

SYNOPSIS
$radiobutton = $parent->Radiobutton(?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 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.

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 radiobutton 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 radiobutton: normal, active, or disabled. In normal state the radiobutton is displayed using the foreground and background options. The active state is typically used when the pointer is over the radiobutton. In active state the radiobutton is displayed using the activeForeground and activeBackground options. Disabled state means that the radiobutton 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 radiobutton is displayed.

Name:	value
Class:	Value
Switch:	-value
    Specifies value to store in the button's associated variable whenever this button is selected.

Name:	variable
Class:	Variable
Switch:	-variable
    Specifies reference to a variable to set whenever this button is selected. Changes in this variable also cause the button to select or deselect itself. Defaults to the value "\$Tk::selectedButton".

Name:	width
Class:	Width
Switch:	-width
    Specifies a desired width for the button. If an image or bitmap is being displayed in the button, 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 Radiobutton method creates a new window (given by the $widget argument) and makes it into a radiobutton widget. Additional options, described above, may be specified on the command line or in the option database to configure aspects of the radiobutton such as its colors, font, text, and initial relief. The radiobutton 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 radiobutton is a widget that displays a textual string, bitmap or image and a diamond or circle 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 radiobutton has all of the behavior of a simple button: 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 check button.

In addition, radiobuttons can be selected. If a radiobutton is selected, the indicator is normally drawn with a selected appearance, and a Tcl variable associated with the radiobutton 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 round mark inside. If the radiobutton 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 round mark inside. Typically, several radiobuttons share a single variable and the value of the variable indicates which radiobutton is to be selected. When a radiobutton is selected it sets the value of the variable to indicate that fact; each radiobutton also monitors the value of the variable and automatically selects and deselects itself when the variable's value changes. By default the variable selectedButton is used; its contents give the name of the button that is selected, or the empty string if no button associated with that variable is selected. The name of the variable for a radiobutton, plus the variable to be stored into 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 radiobutton is configured to select itself on button clicks.

WIDGET METHODS
The Radiobutton 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 radiobutton widgets:

$radiobutton->deselect
    Deselects the radiobutton and sets the associated variable to an empty string. If this radiobutton was not currently selected, the command has no effect.

$radiobutton->flash
    Flashes the radiobutton. This is accomplished by redisplaying the radiobutton several times, alternating between active and normal colors. At the end of the flash the radiobutton is left in the same normal/active state as when the command was invoked. This command is ignored if the radiobutton's state is disabled.

$radiobutton->invoke
    Does just what would have happened if the user invoked the radiobutton with the mouse: selects the button and invokes its associated Tcl command, if there is one. The return value is the return value from the Tcl command, or an empty string if there is no command associated with the radiobutton. This command is ignored if the radiobutton's state is disabled.

$radiobutton->select
    Selects the radiobutton and sets the associated variable to the value corresponding to this widget.

BINDINGS
Tk automatically creates class bindings for radiobuttons that give them the following default behavior:

[1] On Unix systems, a radiobutton activates whenever the mouse passes over it and deactivates whenever the mouse leaves the radiobutton. On Mac and Windows systems, when mouse button 1 is pressed over a radiobutton, 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 radiobutton it is invoked (it becomes selected and the command associated with the button is invoked, if there is one).

[3] When a radiobutton has the input focus, the space key causes the radiobutton to be invoked.

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

    The behavior of radiobuttons can be changed by defining new bindings for individual widgets or by redefining the class bindings.

KEYWORDS
radiobutton, widget