button(n) Tk (4.4) button(n)
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NAME
button - Create and manipulate button widgets
SYNOPSIS
button 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 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. ring.
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
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button(n) Tk (4.4) button(n)
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: 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 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.
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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
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button(n) Tk (4.4) button(n)
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 active
and normal 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
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button(n) Tk (4.4) button(n)
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.
KEYWORDS
button, widget
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