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button(n) Tk Built-In Commands button(n)
NAME
button - Create and manipulate button widgets
SYNOPSIS
button pathName ?options? -activebackground -font -relief
-activeforeground -foreground -repeatdelay -anchor -highlight-
background -repeatinterval -background -highlight-
color -takefocus -bitmap -highlightthickness -text -border-
width -image -textvariable -compound -justify -underline -cur-
sor -padx -wraplength -disabledforeground -pady
WIDGET-SPECIFIC OPTIONS
Specifies a Tcl command to associate with the button. This command is
typically invoked when mouse button 1 is released over the button win-
dow. 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 appear-
ance. The normal and active states will result in buttons of the same
size. In disabled state, the button is drawn with the non-default but-
ton appearance without leaving space for the default appearance. The
disabled state may result in a smaller button than the active state.
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 isn't specified, the button's desired height
is computed from the size of the image or bitmap or text being dis-
played in it. 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. Specifies one of three states
for the button: normal, active, or disabled. In normal state the but-
ton 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 wid-
get and will ignore mouse button presses. In this state the disabled-
Foreground and background options determine how the button is dis-
played. Specifies a desired width 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
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 dis-
played in it.
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
occupy multiple lines on the screen (if it contains newlines or if
wrapping occurs because of the wrapLength option) and one of the char-
acters 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 active and normal colors.
At the end of the flash the button is left in the same nor-
mal/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 dis-
abled.
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 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
individual widgets or by redefining the class bindings.
KEYWORDS
button, widget
Tk 4.4 button(n)
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