Tk::Radiobutton - Create and manipulate Radiobutton widgets
$radiobutton =
$parent->Radiobutton(?options?);
-activebackground -activeforeground -anchor
-background -bitmap -borderwidth -compound
-cursor -disabledforeground -font -foreground
-highlightbackground -highlightcolor
-highlightthickness -image -justify -padx
-pady -relief -takefocus -text
-textvariable -underline -wraplength
See Tk::options for details of the standard 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.
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.
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.
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.