## radiobutton

Create and manipulate radiobutton widgets

### SYNOPSIS

(radiobutton widget-name ?options?-

### STANDARD OPTIONS

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

### WIDGET-SPECIFIC OPTIONS

Name: command
Class: Command
Option keyword: :command
STklos slot name: command
  Specifies a STk procedure to associate with the button. This procedure 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 procedure is invoked.

Name: height
Class: Height
Option keyword: :height
STklos slot name: 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
Option keyword: :indicatoron
STklos slot name: indicator-on
  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: selectColor
Class: Background
Option keyword: :selectcolor
STklos slot name: select-color
  Specifies a background color to use when the button is selected. If indicatorOn is true, the color applicies to the indicator. 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, no special color is used for displaying when the widget is selected.

Name: selectImage
Class: SelectImage
Option keyword: :selectimage
STklos slot name: select-image
  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
Option keyword: :state
STklos slot name: 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: stringvalue
Class: StringValue
Option keyword: :stringvalue
STklos slot name: string-value
  Specifies if the value set to variable by :value must be stringified. Default value for this option is #t. See checkbutton for a similar example.

Name: value
Class: Value
Option keyword: :value
STklos slot name: value
  Specifies value to store in the button's associated variable whenever this button is selected.

Name: variable
Class: Variable
Option keyword: :variable
STklos slot name: variable
  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. Defaults to the value *selected-button*.

Name: width
Class: Width
Option keyword: :width
STklos slot name: 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 procedure creates a new window (given by the widget-name argument) and makes it into a radiobutton widget. Additional options, described above, may be specified on the procedure line or in the option database to configure aspects of the radiobutton such as its colors, font, text, and initial relief. The radiobutton procedure returns its widget-name argument. At the time this procedure is invoked, there must not exist a window named widget-name, but widget-name's parent must exist.

A radiobutton is a widget that displays a textual string, bitmap or image and a diamond 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 STk procedure 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 sunken relief and a special color, and a STk variable associated with the radiobutton is set to a particular value. If the radiobutton is not selected, the indicator is drawn with a raised relief and no special color. 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 *selected-button* 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 procedure 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 radio button is configured to select itself on button clicks.

### WIDGET PROCEDURE

The radiobutton procedure creates a new STk procedure whose name is widget-name. This procedure may be used to invoke various operations on the widget. It has the following general form:

    (widget-name option ?arg arg ...?)

Option and the args determine the exact behavior of the procedure. The following procedures are possible for radiobutton widgets:

(widget-name 'cget option)
  Returns the current value of the configuration option given by option. Option may have any of the values accepted by the radiobutton procedure.

(widget-name 'configure ?option? ?value option value ...?)
  Query or modify the configuration options of the widget. If no option is specified, returns a list describing all of the available options for widget-name (see Tk_ConfigureInfo for information on the format of this list). If option is specified with no value, the procedure returns a list describing the one named option (this list will be identical to the corresponding sublist of the value returned if no option is specified). If one or more option-value pairs are specified, the procedure modifies the given widget option(s) to have the given value(s); in this case the procedure returns an empty string. Option may have any of the values accepted by the radiobutton procedure.

(widget-name 'deselect)
  Deselects the radiobutton and sets the associated variable to an empty string. If this radiobutton was not currently selected, the procedure has no effect.

(widget-name '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 procedure was invoked. This procedure is ignored if the radiobutton's state is disabled.

(widget-name 'invoke)
  Does just what would have happened if the user invoked the radiobutton with the mouse: selects the button and invokes its associated STk procedure, if there is one (return value is undifined).. This procedure is ignored if the radiobutton's state is disabled.

(widget-name '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. The radiobutton activates whenever the mouse passes over it and deactivates whenever the mouse leaves the radiobutton.
2. When mouse button 1 is pressed over a radiobutton it is invoked (it becomes selected and the procedure 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.

### SEE ALSO

button, checkbutton

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