'\"
'\" Copyright (c) 1990-1994 The Regents of the University of California.
'\" Copyright (c) 1994-1995 Sun Microsystems, Inc.
'\" Copyright (c) 1996-1999 Christian Werner
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.so man.macros
.TH scrollbar n 8.0 Ck "Ck Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
scrollbar \- Create and manipulate scrollbar widgets
.SH SYNOPSIS
\fBscrollbar\fI pathName \fR?\fIoptions\fR?
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 4c 8c 12c
\fBactiveAttributes\fR	\fBactiveForeground\fR	\fBbackground\fR	\fBorient\fR
\fBactiveBackground\fR	\fBattributes\fR	\fBforeground\fR	\fBtakeFocus\fR
.fi
.LP
See the ``options'' manual entry for details on the standard options.
.SH "WIDGET-SPECIFIC OPTIONS"
.ta 4c
.LP
.nf
Name:	\fBcommand\fR
Class:	\fBCommand\fR
Command-Line Switch:	\fB\-command\fR
.fi
.IP
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 command is
invoked.  The actual command consists of this option followed by
additional information as described later.
.BE

.SH DESCRIPTION
.PP
The \fBscrollbar\fR command creates a new window (given by the
\fIpathName\fR argument) and makes it into a scrollbar widget.
Additional options, described above, may be specified on the command
line or in the option database to configure aspects of the scrollbar
such as its colors, orientation, and relief.
The \fBscrollbar\fR command returns its \fIpathName\fR argument.
At the time this command is invoked, there must not exist a window
named \fIpathName\fR, but \fIpathName\fR's parent must exist.
.PP
A scrollbar is a widget that displays two arrows, one at each end of
the scrollbar, and a \fIslider\fR in the middle portion of the
scrollbar.
It provides information about what is visible in an \fIassociated window\fR
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 arrows, it means that the associated window displays
the top third of its document.
.PP
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.

.SH "ELEMENTS"
A scrollbar displays five elements, which are referred to in the
widget commands for the scrollbar:
.TP 10
\fBarrow1\fR
The top or left arrow in the scrollbar.
.TP 10
\fBtrough1\fR
The region between the slider and \fBarrow1\fR.
.TP 10
\fBslider\fR
The rectangle that indicates what is visible in the associated widget.
.TP 10
\fBtrough2\fR
The region between the slider and \fBarrow2\fR.
.TP 10
\fBarrow2\fR
The bottom or right arrow in the scrollbar.

.SH "WIDGET COMMAND"
.PP
The \fBscrollbar\fR command creates a new Tcl command whose
name is \fIpathName\fR.  This
command may be used to invoke various
operations on the widget.  It has the following general form:
.DS C
\fIpathName option \fR?\fIarg arg ...\fR?
.DE
\fIOption\fR and the \fIarg\fRs
determine the exact behavior of the command.  The following
commands are possible for scrollbar widgets:
.TP
\fIpathName \fBactivate\fR
Marks the scrollbar as active, which
causes it to be displayed as specified by the
\fBactiveAttributes\fR, \fBactiveBackground\fR and \fBactiveForeground\fR
options.
.TP
\fIpathName \fBcget\fR \fIoption\fR
Returns the current value of the configuration option given
by \fIoption\fR.
\fIOption\fR may have any of the values accepted by the \fBscrollbar\fR
command.
.TP
\fIpathName \fBconfigure\fR ?\fIoption\fR? ?\fIvalue option value ...\fR?
Query or modify the configuration options of the widget.
If no \fIoption\fR is specified, returns a list describing all of
the available options for \fIpathName\fR. If \fIoption\fR is specified
with no \fIvalue\fR, 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 \fIoption\fR is specified).  If
one or more \fIoption\-value\fR 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.
\fIOption\fR may have any of the values accepted by the \fBscrollbar\fR
command.
.TP
\fIpathName \fBdeactivate\fR
Marks the scrollbar as normal, which
causes it to be displayed as specified by the
\fBattributes\fR, \fBbackground\fR and \fBforeground\fR options.
.TP
\fIpathName \fBfraction \fIx y\fR
Returns a real number between 0 and 1 indicating where the point
given by \fIx\fR and \fIy\fR 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.
\fIX\fR and \fIy\fR must be screen coordinates relative to the scrollbar
widget.
If \fIx\fR and \fIy\fR refer to a point outside the trough, the closest
point in the trough is used.
.TP
\fIpathName \fBget\fR
Returns the scrollbar settings in the form of a list whose
elements are the arguments to the most recent \fBset\fR widget command.
.TP
\fIpathName \fBidentify\fR \fIx y\fR
Returns the name of the element under the point given by \fIx\fR and
\fIy\fR (such as \fBarrow1\fR), or an empty string if the point does
not lie in any element of the scrollbar.
\fIX\fR and \fIy\fR must be screen coordinates relative to the scrollbar
widget.
.TP
\fIpathName \fBset\fR \fIfirst last\fR
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 document that is visible in
the associated widget.
For example, if \fIfirst\fR is 0.2 and \fIlast\fR 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.

.SH "SCROLLING COMMANDS"
.PP
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 \fB\-command\fR option.
The command may take any of the following forms.
In each case, \fIprefix\fR is the contents of the
\fB\-command\fR option, which usually has a form like \fB.t yview\fR
.TP
\fIprefix \fBmoveto \fIfraction\fR
\fIFraction\fR is a real number between 0 and 1.
The widget should adjust its view so that the point given
by \fIfraction\fR appears at the beginning of the widget.
If \fIfraction\fR 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.
.TP
\fIprefix \fBscroll \fInumber \fBunit\fR
The widget should adjust its view by \fInumber\fR units.
The units are defined in whatever way makes sense for the widget,
such as characters or lines in a text widget.
\fINumber\fR 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.
.TP
\fIprefix \fBscroll \fInumber \fBpage\fR
The widget should adjust its view by \fInumber\fR 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.
\fINumber\fR is either 1, which means the next page should
become visible, or \-1, which means that the previous page should
become visible.

.SH BINDINGS
Ck 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.

.IP [1]
Pressing button 1 over \fBarrow1\fR 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.
.IP [2]
Pressing button 1 over \fBtrough1\fR 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.
.IP [3]
Pressing button 1 over \fBtrough2\fR 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.
.IP [4]
Pressing button 1 over \fBarrow2\fR 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.
.IP [5]
In vertical scrollbars the Up and Down keys have the same behavior
as mouse clicks over \fBarrow1\fR and \fBarrow2\fR, respectively.
In horizontal scrollbars these keys have no effect.
.IP [6]
In horizontal scrollbars the Left and Right keys have the same behavior
as mouse clicks over \fBarrow1\fR and \fBarrow2\fR, respectively.
In vertical scrollbars these keys have no effect.
.IP [7]
The Prior and Next keys have the same behavior
as mouse clicks over \fBtrough1\fR and \fBtrough2\fR, respectively.
.IP [8]
The Home key adjusts the view to the top (left edge) of the document.
.IP [9]
The End key adjusts the view to the bottom (right edge) of the document.
.IP [10]
FocusIn and FocusOut events activate and deactive the scrollbars, respectively.

.SH KEYWORDS
scrollbar, widget