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.so man.macros

.TH button n 4.4 Tk "Tk Built-In Commands"

.BS

'\" Note:  do not modify the .SH NAME line immediately below!

.SH NAME

button \- Create and manipulate button widgets

.SH SYNOPSIS

\fBbutton\fR \fIpathName \fR?\fIoptions\fR?

.SO

\-activebackground      \-cursor        \-highlightthickness    \-takefocus

\-activeforeground      \-disabledforeground    \-image \-text

\-anchor        \-font  \-justify       \-textvariable

\-background    \-foreground    \-padx  \-underline

\-bitmap        \-highlightbackground   \-pady  \-wraplength

\-borderwidth   \-highlightcolor        \-relief

.SE

.SH "WIDGET-SPECIFIC OPTIONS"

.OP \-command command 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.

.OP \-default default Default

.VS

Specifies one of three states for the default ring: \fBnormal\fR,

\fBactive\fR, or \fBdisabled\fR.  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.

.VE

.OP \-height height 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 \fBTk_GetPixels\fR);

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.

.OP \-state state State

Specifies one of three states for the button:  \fBnormal\fR, \fBactive\fR,

or \fBdisabled\fR.  In normal state the button is displayed using the

\fBforeground\fR and \fBbackground\fR options.  The active state is

typically used when the pointer is over the button.  In active state

the button is displayed using the \fBactiveForeground\fR and

\fBactiveBackground\fR 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 \fBdisabledForeground\fR and

\fBbackground\fR options determine how the button is displayed.

.OP \-width width 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 \fBTk_GetPixels\fR);

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.

.BE

.SH DESCRIPTION

.PP

The \fBbutton\fR command creates a new window (given by the

\fIpathName\fR 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 \fBbutton\fR command returns its

\fIpathName\fR argument.  At the time this command is invoked,

there must not exist a window named \fIpathName\fR, but

\fIpathName\fR's parent must exist.

.PP

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 \fBwrapLength\fR option) and

one of the characters may optionally be underlined using the

\fBunderline\fR option.

It can display itself in either of three different ways, according

to

the \fBstate\fR 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 \fB\-command\fR

option is invoked.

.SH "WIDGET COMMAND"

.PP

The \fBbutton\fR command creates a new Tcl command whose

name is \fIpathName\fR.  This

command may be used to invoke various

operations on the widget.  It has the following general form:

.CS

\fIpathName option \fR?\fIarg arg ...\fR?

.CE

\fIOption\fR and the \fIarg\fRs

determine the exact behavior of the command.  The following

commands are possible for button widgets:

.TP

\fIpathName \fBcget\fR \fIoption\fR

Returns the current value of the configuration option given

by \fIoption\fR.

\fIOption\fR may have any of the values accepted by the \fBbutton\fR

command.

.TP

\fIpathName \fBconfigure\fR ?\fIoption\fR? ?\fIvalue option value ...\fR?

Query or modify the configuration options of the widget.

If no \fIoption\fR is specified, returns a list describing all of

the available options for \fIpathName\fR (see \fBTk_ConfigureInfo\fR for

information on the format of this list).  If \fIoption\fR is specified

with no \fIvalue\fR, 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 \fIoption\fR is specified).  If

one or more \fIoption\-value\fR 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.

\fIOption\fR may have any of the values accepted by the \fBbutton\fR

command.

.TP

\fIpathName \fBflash\fR

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 \fBdisabled\fR.

.TP

\fIpathName \fBinvoke\fR

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 \fBdisabled\fR.

.SH "DEFAULT BINDINGS"

.PP

Tk automatically creates class bindings for buttons that give them

default behavior:

.IP [1]

A button activates whenever the mouse passes over it and deactivates

whenever the mouse leaves the button.

.VS

Under Windows, this binding is only active when mouse button 1 has

been pressed over the button.

.VE

.IP [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.

.IP [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.

.IP [4]

When a button has the input focus, the space key causes the button

to be invoked.

.PP

If the button's state is \fBdisabled\fR then none of the above

actions occur:  the button is completely non-responsive.

.PP

The behavior of buttons can be changed by defining new bindings for

individual widgets or by redefining the class bindings.

.SH KEYWORDS

button, widget