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



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NAME
       scrollbar - Create and manipulate scrollbar widgets

SYNOPSIS
       scrollbar pathName ?options?

STANDARD OPTIONS
       activeAttributes		      activeForegroundbackgroundorient
       activeBackground		      attributes      foregroundtakeFocus

       See the ``options'' manual entry for details on the standard options.

WIDGET-SPECIFIC OPTIONS
       Name:	       command
       Class:	       Command
       Command-Line Switch:-command

	      Specifies	 the  prefix  of a Tcl command to invoke to change the
	      view in the widget associated with the scrollbar.	 When  a  user
	      requests a view change by manipulating the scrollbar, a Tcl com-
	      mand is invoked.	The actual command  consists  of  this	option
	      followed by additional information as described later.
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DESCRIPTION
       The scrollbar command creates a new window (given by the pathName argu-
       ment) and makes it into a scrollbar widget.   Additional	 options,  de-
       scribed	above,	may  be specified on the command line or in the option
       database to configure aspects of the scrollbar such as its colors, ori-
       entation, and relief.  The scrollbar command returns its pathName argu-
       ment.  At the time this command is invoked, there must not exist a win-
       dow named pathName, but pathName'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).   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 ar-
       rows, 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
       commands 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  associ-
		 ated widget.

       trough2	 The region between the slider and arrow2.

       arrow2	 The bottom or right arrow in the scrollbar.


WIDGET COMMAND
       The scrollbar 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 ...?  Op-
       tion and the args determine the exact behavior  of  the	command.   The
       following commands are possible for scrollbar widgets:

       pathName activate
	      Marks  the  scrollbar as active, which causes it to be displayed
	      as specified by the activeAttributes, activeBackground  and  ac-
	      tiveForeground options.

       pathName cget option
	      Returns  the  current value of the configuration option given by
	      option.  Option may have any  of	the  values  accepted  by  the
	      scrollbar 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. 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  op-
	      tion-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 scrollbar command.

       pathName deactivate
	      Marks the scrollbar as normal, which causes it to	 be  displayed
	      as  specified  by	 the attributes, background and foreground op-
	      tions.

       pathName 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 screen 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.

       pathName get
	      Returns the scrollbar settings in the form of a list whose  ele-
	      ments are the arguments to the most recent set widget command.

       pathName identify x y
	      Returns the name of the element under the point given by x and y
	      (such as arrow1), or an empty string if the point does  not  lie
	      in any element of the scrollbar.	X and y must be screen coordi-
	      nates relative to the scrollbar widget.

       pathName set first last
	      This command is invoked by the scrollbar's associated widget  to
	      tell  the	 scrollbar  about the current view in the widget.  The
	      command takes two arguments, each of which is  a	real  fraction
	      between  0 and 1.	 The fractions describe the range of the docu-
	      ment 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 COMMANDS
       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 evaluating a
       Tcl command generated from the scrollbar's -command option.   The  com-
       mand  may take any of the following forms.  In each case, prefix is the
       contents of the -command option, which usually has a form like .t yview

       prefix moveto fraction
	      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 docu-
	      ment, 0.333 refers to a point one-third of the way  through  the
	      document, and so on.

       prefix scroll number unit
	      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.

       prefix scroll number page
	      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.


BINDINGS
       Ck  automatically  creates class bindings for scrollbars that give them
       the following default behavior.	If the behavior is different for  ver-
       tical  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 ap-
	      pears to move down (right) one unit.

       [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.

       [3]    Pressing button 1 over trough2 causes the view in the associated
	      widget  to shift down (right) by one screenful so that the docu-
	      ment appears to move up (left) one screenful.

       [4]    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.

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

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

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

       [8]    The Home key adjusts the view to the top (left edge) of the doc-
	      ument.

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

       [10]   FocusIn  and  FocusOut  events activate and deactive the scroll-
	      bars, respectively.


KEYWORDS
       scrollbar, widget



Ck				      8.0			  scrollbar(n)
