button(n) - phpMan

button(n) Tk Built-In Commands button(n)

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NAME
button - Create and manipulate button 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 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.
[-default 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 appear-
ance 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. [-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 Tk_GetPixels); for text it is in lines of text. If this option is not spec-
ified, the button's desired height is computed from the size of the image or bitmap or
text being displayed in it. [-overrelief 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. [-state 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. [-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 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 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 dis-
played, 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 but-
ton (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 speci-
fied, 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 speci-
fied 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 com-
mand 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 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.

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