button(3tk) Tk Built-In Commands button(3tk)
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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 com-
mand 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, ac-
tive, or disabled. In active state, the button is drawn with
the platform specific appearance for a default button. In nor-
mal state, the button is drawn with the platform specific ap-
pearance 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 bit-
map 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 im-
age 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 typi-
cally used when the pointer is over the button. In active state
the button is displayed using the -activeforeground and -active-
background 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.
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DESCRIPTION
The button command creates a new window (given by the pathName argu-
ment) 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 oc-
cupy multiple lines on the screen (if it contains newlines or if wrap-
ping 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 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 but-
ton 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 avail-
able 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 but-
ton several times, alternating between the configured active-
background and background colors. At the end of the flash the
button is left in the same normal/active state as when the com-
mand 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 dis-
abled.
DEFAULT BINDINGS
Tk automatically creates class bindings for buttons that give them de-
fault behavior:
[1] A button activates whenever the mouse passes over it and deacti-
vates 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 invo-
cation occurs.
[4] When a button has the input focus, the space key causes the but-
ton 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 in-
dividual widgets or by redefining the class bindings.
PLATFORM NOTES
On Aqua/Mac OS X, some configuration options are ignored for the pur-
pose 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 -re-
lief.
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)
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