button(n) Tk Built-In Commands button(n)_________________________________________________________________NAMEbutton - Create and manipulate button widgets
SYNOPSISbutton pathName ?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 the options manual entry for details on the standard
options.
WIDGET-SPECIFIC OPTIONS
Command-Line Name:-command
Database Name: command
Database Class: Command
Specifies a Tcl command to associate with the but-
ton. This command is typically invoked when mouse
button 1 is released over the button window.
Command-Line Name:-height
Database Name: height
Database Class: 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.
Command-Line Name:-state
Database Name: state
Database Class: State
Specifies one of three states for the button: nor-
mal, active, or disabled. In normal state the but-
ton is displayed using the foreground and back-
ground options. The active state is typically used
when the pointer is over the button. In active
state the button is displayed using the activeFore-
ground and activeBackground options. Disabled
state means that the button should be insensitive:
the default bindings will refuse to activate the
Tk 4.0 1
button(n) Tk Built-In Commands button(n)
widget and will ignore mouse button presses. In
this state the disabledForeground and background
options determine how the button is displayed.
Command-Line Name:-width
Database Name: width
Database Class: Width
Specifies a desired width 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 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 button command creates a new window (given by the
pathName argument) and makes it into a button widget.
Additional options, described above, may be specified on
the command line or in the option database to configure
aspects of the button such as its colors, font, text, and
initial relief. The button command returns its pathName
argument. At the time this command is invoked, there must
not exist a window named pathName, but pathName's parent
must exist.
A button is a widget that displays a textual string,
bitmap or image. 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 charac-
ters may optionally be underlined using the underline
option. It can display itself in either of three differ-
ent ways, according to the state option; it can be made to
appear raised, sunken, or flat; and it can be made to
flash. When a user invokes the button (by pressing mouse
button 1 with the cursor over the button), then the Tcl
command specified in the -command option is invoked.
WIDGET COMMAND
The button command creates a new Tcl command whose name is
pathName. This command may be used to invoke various
operations on the widget. It has the following general
form:
pathName option ?arg arg ...?
Option and the args determine the exact behavior of the
command. The following commands are possible for button
widgets:
Tk 4.0 2
button(n) Tk Built-In Commands button(n)
pathName cget option
Returns the current value of the configuration
option given by option. Option may have any of the
values accepted by the button command.
pathName 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 path-
Name (see Tk_ConfigureInfo for information on the
format of this list). If option is specified with
no value, then the command returns a list describ-
ing the one named option (this list will be identi-
cal to the corresponding sublist of the value
returned if no option is specified). If one or
more option-value pairs are specified, then the
command modifies the given widget option(s) to have
the given value(s); in this case the command
returns an empty string. Option may have any of
the values accepted by the button command.
pathName flash
Flash the button. This is accomplished by redis-
playing the button several times, alternating
between active and normal colors. At the end of
the flash the button is left in the same nor-
mal/active state as when the command was invoked.
This command is ignored if the button's state is
disabled.
pathName invoke
Invoke the Tcl command associated with the button,
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 button.
This command is ignored if the button's state is
disabled.
DEFAULT BINDINGS
Tk automatically creates class bindings for buttons that
give them the following default behavior:
[1] A button activates whenever the mouse passes over
it and deactivates whenever the mouse leaves the
button.
[2] A button's relief is changed to sunken whenever
mouse button 1 is pressed over the button, and the
relief is restored to its original value when but-
ton 1 is later released.
[3] If mouse button 1 is pressed over a button and
later released over the button, the button is
Tk 4.0 3
button(n) Tk Built-In Commands button(n)
invoked. However, if the mouse is not over the
button when button 1 is released, then no invoca-
tion occurs.
[4] When a button has the input focus, the space key
causes the button to be invoked.
If the button's state is disabled then none of the above
actions occur: the button is completely non-responsive.
The behavior of buttons can be changed by defining new
bindings for individual widgets or by redefining the class
bindings.
KEYWORDS
button, widget
Tk 4.0 4
