button - Create and manipulate 'button' action widgets
button pathName ?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.
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.
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.
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.
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.
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.
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