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



NAME
       scrollbar - Create and manipulate scrollbar widgets

SYNOPSIS
       (scrollbar widget-name ?options?)
       :activebackground   :highlightbackground     :orient   :takefocus
       :background    :highlightcolor     :relief   :troughcolor
       :borderwidth   :highlightthickness :repeatdelay
       :cursor   :jump     :repeatinterval

WIDGET-SPECIFIC OPTIONS
       [:activerelief activeRelief] Specifies the relief to use when
       displaying the element that is active, if any.  Elements other than the
       active element are always displayed with a raised relief.
       [:command command] Specifies a STk procedure to invoke to change the
       view in the widget associated with the scrollbar.  When a user requests
       a view change by manipulating the scrollbar, the procedure is invoked.
       The parameters given to this procedure are described later.
       [:elementborderwidth elementBorderWidth] Specifies the width of borders
       drawn around the internal elements of the scrollbar (the two arrows and
       the slider).  The value may have any of the forms acceptable to
       Tk_GetPixels.  If this value is less than zero, the value of the
       borderWidth option is used in its place.  [:width width] Specifies the
       desired narrow dimension of the scrollbar window, not including 3-D
       border, if any.  For vertical scrollbars this will be the width and for
       horizontal scrollbars this will be the height.  The value may have any
       of the forms acceptable to Tk_GetPixels.


DESCRIPTION
       The scrollbar procedure creates a new window (given by the widget-name
       argument) and makes it into a scrollbar widget.  Additional options,
       described above, may be specified on the procedure line or in the
       option database to configure aspects of the scrollbar such as its
       colors, orientation, and relief.  The scrollbar 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 scrollbar is a widget that displays two arrows, one at each end of
       the scrollbar, and a slider in the middle portion of the scrollbar.  It
       provides information about what is visible in an associated window that
       displays an document of some sort (such as a file being edited or a
       drawing).  The position and size of the slider indicate which portion
       of the document is visible in the associated window.  For example, if
       the slider in a vertical scrollbar covers the top third of the area
       between the two arrows, it means that the associated window displays
       the top third of its document.

       Scrollbars can be used to adjust the view in the associated window by
       clicking or dragging with the mouse.  See the BINDINGS section below
       for details.


ELEMENTS
       A scrollbar displays five elements, which are referred to in the widget
       procedures for the scrollbar:

       arrow1    The top or left arrow in the scrollbar.

       trough1   The region between the slider and arrow1.

       slider    The rectangle that indicates what is visible in the
                 associated widget.

       trough2   The region between the slider and arrow2.

       arrow2    The bottom or right arrow in the scrollbar.


WIDGET PROCEDURE
       The scrollbar 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 scrollbar
       widgets:

       (widget-name 'activate )

       (widget-name 'activate element)
              Marks the element indicated by element as active, which causes
              it to be displayed as specified by the activeBackground and
              activeRelief options.  The only element values understood by
              this procedure are arrow1, slider, or arrow2.  If any other
              value is specified then no element of the scrollbar will be
              active.  If element is not specified, the procedure returns the
              name of the element that is currently active, or an empty list
              if no element is active.

       (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
              scrollbar 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
              scrollbar procedure.

       (widget-name 'delta deltaX deltaY)
              Returns a real number indicating the fractional change in the
              scrollbar setting that corresponds to a given change in slider
              position.  For example, if the scrollbar is horizontal, the
              result indicates how much the scrollbar setting must change to
              move the slider deltaX pixels to the right (deltaY is ignored in
              this case).  If the scrollbar is vertical, the result indicates
              how much the scrollbar setting must change to move the slider
              deltaY pixels down.  The arguments and the result may be zero or
              negative.

       (widget-name 'fraction x y)
              Returns a real number between 0 and 1 indicating where the point
              given by x and y lies in the trough area of the scrollbar.  The
              value 0 corresponds to the top or left of the trough, the value
              1 corresponds to the bottom or right, 0.5 corresponds to the
              middle, and so on.  X and y must be pixel coordinates relative
              to the scrollbar widget.  If x and y refer to a point outside
              the trough, the closest point in the trough is used.

       (widget-name 'get)
              Returns the scrollbar settings in the form of a list whose
              elements are the arguments to the most recent set widget
              procedure.

       (widget-name 'identify x y)
              Returns the name of the element under the point given by x and y
              (such as "arrow1"), or  #fif the point does not lie in any
              element of the scrollbar.  X and y must be pixel coordinates
              relative to the scrollbar widget.

       (widget-name 'set first last)
              This procedure is invoked by the scrollbar's associated widget
              to tell the scrollbar about the current view in the widget.  The
              procedure takes two arguments, each of which is a real fraction
              between 0 and 1.  The fractions describe the range of the
              document that is visible in the associated widget.  For example,
              if first is 0.2 and last is 0.4, it means that the first part of
              the document visible in the window is 20% of the way through the
              document, and the last visible part is 40% of the way through.


SCROLLING PROCEDURES
       When the user interacts with the scrollbar, for example by dragging the
       slider, the scrollbar notifies the associated widget that it must
       change its view.  The scrollbar makes the notification by calling the
       STk procedure given to the scrollbar's command option. The parameters
       passed to the procedure may take any of the following forms:

       Fraction is a real number between 0 and 1.
              The widget should adjust its view so that the point given by
              fraction appears at the beginning of the widget.  If fraction is
              0 it refers to the beginning of the document.  1.0 refers to the
              end of the document, 0.333 refers to a point one-third of the
              way through the document, and so on.

       The widget should adjust its view by number units.
              The units are defined in whatever way makes sense for the
              widget, such as characters or lines in a text widget.  Number is
              either 1, which means one unit should scroll off the top or left
              of the window, or -1, which means that one unit should scroll
              off the bottom or right of the window.

       The widget should adjust its view by number pages.
              It is up to the widget to define the meaning of a page;
              typically it is slightly less than what fits in the window, so
              that there is a slight overlap between the old and new views.
              Number is either 1, which means the next page should become
              visible, or -1, which means that the previous page should become
              visible.


OLD PROCEDURE SYNTAX
       In versions of Tk before 4.0, the set and get widget procedures used a
       different form.  This form is still supported for backward
       compatibility, but it is deprecated.  In the old procedure syntax, the
       set widget procedure has the following form:

       (widget-name 'set totalUnits windowUnits firstUnit lastUnit)
              In this form the arguments are all integers.  TotalUnits gives
              the total size of the object being displayed in the associated
              widget.  The meaning of one unit depends on the associated
              widget;  for example, in a text editor widget units might
              correspond to lines of text.  WindowUnits indicates the total
              number of units that can fit in the associated window at one
              time.  FirstUnit and lastUnit give the indices of the first and
              last units currently visible in the associated window (zero
              corresponds to the first unit of the object).

       Under the old syntax the get widget procedure returns a list of four
       integers, consisting of the totalUnits, windowUnits, firstUnit, and
       lastUnit values from the last set widget procedure.

       The procedures generated by scrollbars also have a different form when
       the old syntax is being used: a single parameter is passed to the
       procedure given to the :command option. This integer indicates what
       should appear at the top or left of the associated widget's window.  It
       has the same meaning as the firstUnit and lastUnit arguments to the set
       widget procedure.

       The most recent set widget procedure determines whether or not to use
       the old syntax.  If it is given two real arguments then the new syntax
       will be used in the future, and if it is given four integer arguments
       then the old syntax will be used.


EXAMPLE
       The following example shows a procedure which is compatible with the
       old and new syntax for procedure scrolling discussed earlier: (listbox
       '.l :height 5             :yscroll (lambda l (apply .s 'set l)))
       (scrollbar '.s :command (lambda l (apply .l 'yview l)))

       ;; Set some elements in the listbox (.l 'insert 0 'one 'two 'three
       'four 'five 'six 'seven 'eight)

       ;; Pack elements (pack .l :side "left" :expand #t  :fill "both") (pack
       .s :side "right" :expand #f :fill "y")

       Using apply and a variable length list of parameters for the scrollbar
       procedure is compatible with old and new scrollbar procedure syntax.


BINDINGS
       Tk automatically creates class bindings for scrollbars that give them
       the following default behavior.  If the behavior is different for
       vertical and horizontal scrollbars, the horizontal behavior is
       described in parentheses.


       [1]    Pressing button 1 over arrow1 causes the view in the associated
              widget to shift up (left) by one unit so that the document
              appears to move down (right) one unit.  If the button is held
              down, the action auto-repeats.

       [2]    Pressing button 1 over trough1 causes the view in the associated
              widget to shift up (left) by one screenful so that the document
              appears to move down (right) one screenful.  If the button is
              held down, the action auto-repeats.

       [3]    Pressing button 1 over the slider and dragging causes the view
              to drag with the slider.  If the jump option is true, then the
              view doesn't drag along with the slider;  it changes only when
              the mouse button is released.

       [4]    Pressing button 1 over trough2 causes the view in the associated
              widget to shift down (right) by one screenful so that the
              document appears to move up (left) one screenful.  If the button
              is held down, the action auto-repeats.

       [5]    Pressing button 1 over arrow2 causes the view in the associated
              widget to shift down (right) by one unit so that the document
              appears to move up (left) one unit.  If the button is held down,
              the action auto-repeats.

       [6]    If button 2 is pressed over the trough or the slider, it sets
              the view to correspond to the mouse position;  dragging the
              mouse with button 2 down causes the view to drag with the mouse.
              If button 2 is pressed over one of the arrows, it causes the
              same behavior as pressing button 1.

       [7]    If button 1 is pressed with the Control key down, then if the
              mouse is over arrow1 or trough1 the view changes to the very top
              (left) of the document;  if the mouse is over arrow2 or trough2
              the view changes to the very bottom (right) of the document;  if
              the mouse is anywhere else then the button press has no effect.

       [8]    In vertical scrollbars the Up and Down keys have the same
              behavior as mouse clicks over arrow1 and arrow2, respectively.
              In horizontal scrollbars these keys have no effect.

       [9]    In vertical scrollbars Control-Up and Control-Down have the same
              behavior as mouse clicks over trough1 and trough2, respectively.
              In horizontal scrollbars these keys have no effect.

       [10]   In horizontal scrollbars the Up and Down keys have the same
              behavior as mouse clicks over arrow1 and arrow2, respectively.
              In vertical scrollbars these keys have no effect.

       [11]   In horizontal scrollbars Control-Up and Control-Down have the
              same behavior as mouse clicks over trough1 and trough2,
              respectively.  In vertical scrollbars these keys have no effect.

       [12]   The Prior and Next keys have the same behavior as mouse clicks
              over trough1 and trough2, respectively.

       [13]   The Home key adjusts the view to the top (left edge) of the
              document.

       [14]   The End key adjusts the view to the bottom (right edge) of the
              document.




STk                                   3.1                         scrollbar(n)
