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



NAME
       button - Create and manipulate button widgets

SYNOPSIS
       (button widget-name ?options?)
       :activebackground   :cursor   :highlightthickness :takefocus
       :activeforeground   :disabledforeground :image    :text
       :anchor   :font     :justify  :textvariable
       :background    :foreground    :padx     :underline
       :bitmap   :highlightbackground     :pady     :wraplength
       :borderwidth   :highlightcolor     :relief

WIDGET-SPECIFIC OPTIONS
       [:command command] Specifies a STk procedure to associate with the
       button.  This procedure is typically invoked when mouse button 1 is
       released over the button window.  OP :default default 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 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.  [:environment environment] Specifies the environment in which
       the :textvariable must be taken.  By default, the value of this option
       is the STk global environment.  [: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 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:  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 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 procedure creates a new window (given by the widget-name
       argument) and makes it into a button widget.  Additional options,
       described above, may be specified on the procedure line or in the
       option database to configure aspects of the button such as its colors,
       font, text, and initial relief.  The button procedure returns its
       widget-name argument.  At the time this procedure is invoked, there
       must not exist a window named widget-name, but widget-name'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
       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 STk procedure
       specified in the :command option is invoked.


WIDGET PROCEDURE
       The button procedure creates a new STk procedure whose name is
       widget-name.  This procedure may be used to invoke various operations
       on the widget.  It has the following general form: (widget-name option
       ?arg arg ...?)  Option and the args determine the exact behavior of the
       procedure.  The following procedures are possible for button widgets:

       (widget-name 'cget option)
              Returns the current value of the configuration option given by
              option.  Option may have any of the values accepted by the
              button procedure.

       (widget-name '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 widget-name (see Tk_ConfigureInfo for
              information on the format of this list).  If option is specified
              with no value, then the procedure 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 procedure modifies the given widget option(s) to have
              the given value(s);  in this case the procedure returns an empty
              string.  Option may have any of the values accepted by the
              button procedure.

       (widget-name '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 procedure was invoked.  This
              procedure is ignored if the button's state is disabled.

       (widget-name 'invoke)
              Invoke the STk procedure associated with the button, if there is
              one (return value is undefined).  This procedure 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.


SEE ALSO
       checkbutton, radiobutton



STk                                   4.0                            button(n)
