xref: /inferno-os/man/9/button (revision 46439007cf417cbd9ac8049bb4122c890097a0fa)
BUTTON 9
NAME
button - Create and manipulate button widgets
SYNOPSIS
\f5button pathName ?options?
STANDARD OPTIONS
.EX -activebackground -disabledcolor -justify -activeforeground -font -relief -anchor -foreground -takefocus -background -highlightcolor -text -bitmap -highlightthickness -underline -borderwidth -image
"WIDGET-SPECIFIC OPTIONS"

-command tkcmd Specifies a Tk command to associate with the button. This command is typically invoked when mouse button 1 is released over the button window.

-height dist Specifies a desired height for the button. 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.

-state state Specifies one of three states for the button: \f5normal, \f5active, or \f5disabled. In normal state the button is displayed using the \f5foreground and \f5background options. The active state is typically used when the pointer is over the button. In active state the button is displayed using the \f5activeForeground and \f5activeBackground 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 \f5background option determines how the button is displayed.

-width dist Specifies a desired width for the button. 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 \f5button 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. to configure aspects of the button such as its colours, font, text, and initial relief. The \f5button command returns its pathName argument. At the time this command is invoked, there must not exist a window named pathName.

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) and one of the characters may optionally be underlined using the \f5underline option. It can display itself in either of three different ways, according to the \f5state option; it can be made to appear raised, sunken, or flat. When a user invokes the button (by pressing mouse button 1 with the cursor over the button), then the Tk command specified in the \f5-command option is invoked.

"WIDGET COMMAND"
The \f5button command creates a new Tk command whose name is pathName. This command may be used to invoke various operations on the widget. It has the following general form:

.EX pathName option ?arg arg ...?

Option and the args determine the exact behaviour of the command. The following commands are possible for button widgets:

pathName \f5cget option Returns the current value of the configuration option given by option. Option may have any of the values accepted by the \f5button command.

pathName \f5configure ?option? ?value option value ...? Query or modify the configuration options of the widget. If no option is specified, returns a list of all of the available options for pathName. 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 \f5button command.

pathName \f5invoke Invoke the Tk command associated with the button, if there is one. The return value is the return value from the Tk command, or an empty string if there is no command associated with the button. This command is ignored if the button's state is \f5disabled.

"DEFAULT BINDINGS"
Tk automatically creates bindings for buttons that give them the following default behaviour:
[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. However, if the mouse is not over the button when button 1 is released, then no invocation occurs.
[4]
If the Enter or Space key is pressed when the button has keyboard focus, the button is invoked.

If the button's state is \f5disabled then none of the above actions occur: the button is completely non-responsive.

The behaviour of buttons can be changed by defining new bindings for individual widgets.

SEE ALSO
checkbutton (9), choicebutton (9), options (9), radiobutton (9), types (9)