Provided by: tk8.6-doc_8.6.14-1build1_all 
NAME
button - Create and manipulate 'button' action widgets
SYNOPSIS
button pathName ?options?
STANDARD OPTIONS
-activebackground -font -relief
-activeforeground -foreground -repeatdelay
-anchor -highlightbackground -repeatinterval
-background -highlightcolor -takefocus
-bitmap -highlightthickness -text
-borderwidth -image -textvariable
-compound -justify -underline
-cursor -padx -wraplength
-disabledforeground -pady
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 button. This command is typically invoked when
mouse button 1 is released over the button window.
Command-Line Name:-default
Database Name: default
Database Class: Default
Specifies one of three states for the default ring: normal, active, or disabled. In active state,
the button is drawn with the platform specific appearance for a default button. In normal state,
the button is drawn with the platform specific appearance for a non-default button, leaving enough
space to draw the default button appearance. The normal and active states will result in buttons
of the same size. In disabled state, the button is drawn with the non-default button appearance
without leaving space for the default appearance. The disabled state may result in a smaller
button than the active state.
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 is not 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:-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.
Command-Line Name:-state
Database Name: state
Database Class: State
Specifies one of three states for the button: normal, active, or disabled. In normal state the
button is displayed using the -foreground and -background options. The active state is typically
used when the pointer is over the button. In active state the button is displayed using the
-activeforeground and -activebackground options. Disabled state means that the button 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 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 a text
button (no image or with -compound none) then the width specifies how much space in characters to
allocate for the text label. If the width is negative then this specifies a minimum width. If
this option is not 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 characters may optionally be underlined
using the -underline option. 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; 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:
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 pathName (see Tk_ConfigureInfo for information on
the format of this list). If option is specified with no value, then the command 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, 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 redisplaying the button several times, alternating
between the configured activebackground and background colors. At the end of the flash the button
is left in the same normal/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 default behavior:
[1] A button activates whenever the mouse passes over it and deactivates whenever the mouse leaves the
button. Under Windows, this binding is only active when mouse button 1 has been pressed over 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 button 1 is later released.
[3] If mouse button 1 is pressed over a button and later released over the button, the button is
invoked. However, if the mouse is not over the button when button 1 is released, then no
invocation 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.
PLATFORM NOTES
On Aqua/Mac OS X, some configuration options are ignored for the purpose of drawing of the widget because
they would otherwise conflict with platform guidelines. The configure and cget subcommands can still
manipulate the values, but do not cause any variation to the look of the widget. The options affected
notably include -background and -relief.
EXAMPLES
This is the classic Tk “Hello, World!” demonstration:
button .b -text "Hello, World!" -command exit
pack .b
This example demonstrates how to handle button accelerators:
button .b1 -text Hello -underline 0
button .b2 -text World -underline 0
bind . <Key-h> {.b1 flash; .b1 invoke}
bind . <Key-w> {.b2 flash; .b2 invoke}
pack .b1 .b2
SEE ALSO
ttk::button(3tk)
KEYWORDS
button, widget
Tk 4.4 button(3tk)