tk4.2 User Commands - button
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:-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 accept-
able 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 activeBack-
ground 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 accept-
able 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 path-
Name argument) and makes it into a button widget. Addi-
tional 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 wra-
pLength 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 opera-
tions on the widget. It has the following general form:
pathName option ?arg arg ...?
Option and the args determine the exact behavior of the com-
mand. The following commands are possible for button widg-
ets:
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 correspond-
ing 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
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 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. How-
ever, 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 bind-
ings for individual widgets or by redefining the class bind-
ings.
KEYWORDS
button, widget