radiobutton(3)
NAME
Tk::Radiobutton - Create and manipulate Radiobutton wid
gets
SYNOPSIS
$radiobutton = $parent->Radiobutton(?options?);
STANDARD OPTIONS
-activebackground -cursor -highlightthickness -takefo
cus -activeforeground -disabledfore
ground -image -text -anchor -font -jus
tify -textvariable -background -fore
ground -padx -underline -bitmap -highlightback
ground -pady -wraplength -borderwidth -high
lightcolor -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 but
ton'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. - 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. Dis abled 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 "k::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 indica_
tor. 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 radiobut
ton 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 dif
ferent 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 vari
able 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, alternat
ing between active and normal colors. At the end of
the flash the radiobutton is left in the same nor
mal/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 com
mand, or an empty string if there is no command asso
ciated with the radiobutton. This command is ignored
if the radiobutton's state is disabled. - $radiobutton->select
- Selects the radiobutton and sets the associated vari
able 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 sys
tems, when mouse button 1 is pressed over a radiobut
ton, 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 asso
ciated 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 com
pletely non-responsive. - The behavior of radiobuttons can be changed by defin
ing new bindings for individual widgets or by redefin
ing the class bindings.
KEYWORDS
- radiobutton, widget