NAME¶
Tk::Radiobutton - Create and manipulate Radiobutton widgets
SYNOPSIS¶
$radiobutton =
$parent->
Radiobutton(?
options?);
STANDARD 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.
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.
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