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scrollbar(n) - scrollbar, scrollbar - Create and manipulate scrollbar widgets - man n scrollbar

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



NAME
       scrollbar - Create and manipulate scrollbar widgets

SYNOPSIS
       scrollbar     pathName    ?options?     -activebackground   -highlight-
       color     -repeatdelay -background    -highlightthickness -repeatinter-
       val   -borderwidth   -jump     -takefocus  -cursor   -orient   -trough-
       color -highlightbackground     -relief

WIDGET-SPECIFIC OPTIONS
       Specifies the relief to use when displaying the element that is active,
       if(3,n)  any.   Elements  other than the active element are always displayed
       with a raised relief.  Specifies the prefix of a Tcl command to  invoke
       to change the view in(1,8) 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.   This  option  almost
       always has a value such as .t xview or .t yview, consisting of the name
       of a widget and either  xview  (if(3,n)  the  scrollbar  is  for  horizontal
       scrolling)  or  yview (for vertical scrolling).  All scrollable widgets
       have xview and yview commands that take exactly  the  additional  argu-
       ments  appended  by  the  scrollbar  as described in(1,8) SCROLLING COMMANDS
       below.  Specifies the width of borders drawn around the  internal  ele-
       ments  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(1,3)  than  zero,  the  value  of the borderWidth option is used in(1,8) its
       place.  Specifies the desired narrow dimension of the scrollbar window,
       not including 3-D border, if(3,n) 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 command creates a new window (given by the pathName argu-
       ment) and makes  it  into  a  scrollbar  widget.   Additional  options,
       described  above, may be specified on the command line or in(1,8) 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(1,2,n) this command is invoked, there must not exist a win-
       dow named(5,8) 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(1,8) the middle portion of the scrollbar.  It
       provides information about what is visible in(1,8) an associated window that
       displays an document of some sort(1,3) (such as a file(1,n)  being  edited  or  a
       drawing).   The  position and size of the slider indicate which portion
       of the document is visible in(1,8) the associated window.  For  example,  if(3,n)
       the  slider  in(1,8)  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(1,8) 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(1,8) the widget
       commands for the scrollbar:

       arrow1    The top or left arrow in(1,8) the scrollbar.

       trough1   The region between the slider and arrow1.

       slider    The rectangle that indicates what is visible in(1,8)  the  associ-
                 ated widget.

       trough2   The region between the slider and arrow2.

       arrow2    The bottom or right arrow in(1,8) 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 ...?
       Option and the args determine the exact behavior of the  command.   The
       following commands are possible for scrollbar widgets:

       pathName 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 command 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 command returns the name of the
              element  that is currently active, or an empty string(3,n) if(3,n) no ele-
              ment is active.

       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 (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(5,8)
              option (this list will be identical to the corresponding sublist
              of the value returned if(3,n) 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(1,8)  this
              case  the  command returns an empty string.  Option may have any
              of the values accepted by the scrollbar command.

       pathName delta deltaX deltaY
              Returns a real number indicating the fractional  change  in(1,8)  the
              scrollbar  setting  that corresponds to a given change in(1,8) slider
              position.  For example, if(3,n)  the  scrollbar  is  horizontal,  the
              result  indicates  how much the scrollbar setting must change to
              move(3x,7,3x curs_move) the slider deltaX pixels to the right (deltaY is ignored in(1,8)
              this  case).  If the scrollbar is vertical, the result indicates
              how much the scrollbar setting must change to  move(3x,7,3x curs_move)  the  slider
              deltaY pixels down.  The arguments and the result may be zero or
              negative.

       pathName fraction x y
              Returns a real number between 0 and 1 indicating where the point
              given  by x and y lies in(1,8) 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(1,8) the trough is used.

       pathName get
              Returns the scrollbar settings in(1,8) the form of a list whose  ele-
              ments are the arguments to the most recent set(7,n,1 builtins) 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(3,n) if(3,n) the point does  not  lie
              in(1,8)  any element of the scrollbar.  X and y must be pixel coordi-
              nates relative to the scrollbar widget.

       pathName set(7,n,1 builtins) first last
              This command is invoked by the scrollbar's associated widget  to
              tell  the  scrollbar  about the current view in(1,8) 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(1,8) the associated widget.  For example,  if(3,n)
              first  is  0.2  and last is 0.4, it means that the first part of
              the document visible in(1,8) 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 units(1,7)
              The widget should adjust its view by number  units.   The  units(1,7)
              are  defined in(1,8) whatever way makes sense for the widget, such as
              characters or lines in(1,8) 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 pages
              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(1,3)  than what fits in(1,8) 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 COMMAND SYNTAX
       In versions of Tk before 4.0, the set(7,n,1 builtins) and get widget  commands  used  a
       different  form.  This form is still supported for backward compatibil-
       ity, but it is deprecated.  In the old command syntax, the  set(7,n,1 builtins)  widget
       command has the following form:

       pathName set(7,n,1 builtins) totalUnits windowUnits firstUnit lastUnit
              In  this  form the arguments are all integers.  TotalUnits gives
              the total size of the object being displayed in(1,8)  the  associated
              widget.   The meaning of one unit depends on the associated wid-
              get;  for example, in(1,8) a text editor widget  units(1,7)  might  corre-
              spond  to lines of text.  WindowUnits indicates the total number
              of units(1,7) that can fit in(1,8) the  associated  window  at  one  time.
              FirstUnit  and  lastUnit  give the indices of the first and last
              units(1,7) currently visible in(1,8) the associated  window  (zero  corre-
              sponds to the first unit of the object).

       Under  the  old  syntax  the  get widget command returns a list of four
       integers, consisting of the  totalUnits,  windowUnits,  firstUnit,  and
       lastUnit values from the last set(7,n,1 builtins) widget command.

       The  commands  generated  by scrollbars also have a different form when
       the old syntax is being used:

       prefix unit
              Unit is an integer that 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(7,n,1 builtins)  wid-
              get command.

       The most recent set(7,n,1 builtins) widget command determines whether or not to use the
       old syntax.  If it is given two real arguments then the new syntax will
       be  used  in(1,8) the future, and if(3,n) it is given four integer arguments then
       the old syntax will be used.


BINDINGS
       Tk 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(1,8) parentheses.


       [1]    Pressing  button 1 over arrow1 causes the view in(1,8) the associated
              widget to shift up (left) by  one  unit  so  that  the  document
              appears  to  move(3x,7,3x curs_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(1,8) the associated
              widget  to shift up (left) by one screenful so that the document
              appears to move(3x,7,3x curs_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(1,8) the associated
              widget  to shift down (right) by one screenful so that the docu-
              ment appears to move(3x,7,3x curs_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(1,8) the associated
              widget to shift down (right) by one unit so  that  the  document
              appears to move(3x,7,3x curs_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(3,n)  the
              mouse is over arrow1 or trough1 the view changes to the very top
              (left) of the document;  if(3,n) the mouse is over arrow2 or  trough2
              the view changes to the very bottom (right) of the document;  if(3,n)
              the mouse is anywhere else then the button press has no  effect.

       [8]    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.

       [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,  respec-
              tively.  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 doc-
              ument.

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


KEYWORDS
       scrollbar, widget



Tk                                    4.1                         scrollbar(n)

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