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'\" RCS: @(#) $Id: scrollbar.n,v 1.1.1.1 2002-01-16 10:25:49 markom Exp $

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.so man.macros

.TH scrollbar n 4.1 Tk "Tk 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\fR \fIpathName \fR?\fIoptions\fR?

.SO

\-activebackground      \-highlightbackground   \-orient        \-takefocus

\-background    \-highlightcolor        \-relief        \-troughcolor

\-borderwidth   \-highlightthickness    \-repeatdelay

\-cursor        \-jump  \-repeatinterval

.SE

.SH "WIDGET-SPECIFIC OPTIONS"

.OP \-activerelief 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.

.OP \-command command 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 command 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 \fB.t xview\fR or \fB.t yview\fR, consisting of the

name of a widget and either \fBxview\fR (if the scrollbar is for

horizontal scrolling) or \fByview\fR (for vertical scrolling).

All scrollable widgets have \fBxview\fR and \fByview\fR commands

that take exactly the additional arguments appended by the scrollbar

as described in SCROLLING COMMANDS below.

.OP \-elementborderwidth elementBorderWidth BorderWidth

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 \fBTk_GetPixels\fR.

If this value is less than zero, the value of the \fBborderWidth\fR

option is used in its place.

.OP \-width 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 \fBTk_GetPixels\fR.

.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 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.

.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"

.PP

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:

.CS

\fIpathName option \fR?\fIarg arg ...\fR?

.CE

\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?\fIelement\fR?

Marks the element indicated by \fIelement\fR as active, which

causes it to be displayed as specified by the \fBactiveBackground\fR

and \fBactiveRelief\fR options.

The only element values understood by this command are \fBarrow1\fR,

\fBslider\fR, or \fBarrow2\fR.

If any other value is specified then no element of the scrollbar

will be active.

If \fIelement\fR is not specified, the command returns

the name of the element that is currently active, or an empty string

if no element is active.

.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 (see \fBTk_ConfigureInfo\fR for

information on the format of this list).  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 \fBdelta \fIdeltaX deltaY\fR

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 \fIdeltaX\fR pixels to the right (\fIdeltaY\fR is

ignored in this case).

If the scrollbar is vertical, the result indicates how much the

scrollbar setting must change to move the slider \fIdeltaY\fR pixels

down.  The arguments and the result may be zero or negative.

.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 pixel 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 pixel 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 \fBunits\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 \fBpages\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 "OLD COMMAND SYNTAX"

.PP

In versions of Tk before 4.0, the \fBset\fR and \fBget\fR widget

commands used a different form.

This form is still supported for backward compatibility, but it

is deprecated.

In the old command syntax, the \fBset\fR widget command has the

following form:

.TP

\fIpathName \fBset\fR \fItotalUnits windowUnits firstUnit lastUnit\fR

In this form the arguments are all integers.

\fITotalUnits\fR 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.  \fIWindowUnits\fR indicates the total number of units that

can fit in the associated window at one time.  \fIFirstUnit\fR

and \fIlastUnit\fR give the indices of the first and last units

currently visible in the associated window (zero corresponds to the

first unit of the object).

.LP

Under the old syntax the \fBget\fR widget command returns a list

of four integers, consisting of the \fItotalUnits\fR, \fIwindowUnits\fR,

\fIfirstUnit\fR, and \fIlastUnit\fR values from the last \fBset\fR

widget command.

.PP

The commands generated by scrollbars also have a different form

when the old syntax is being used:

.TP

\fIprefix\fR \fIunit\fR

\fIUnit\fR 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 \fIfirstUnit\fR and \fIlastUnit\fR

arguments to the \fBset\fR widget command.

.LP

The most recent \fBset\fR 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 the future, and if it is given four integer arguments then

the old syntax will be used.

.SH 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.

.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.

If the button is held down, the action auto-repeats.

.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.

If the button is held down, the action auto-repeats.

.IP [3]

Pressing button 1 over the slider and dragging causes the view

to drag with the slider.

If the \fBjump\fR option is true, then the view doesn't drag along

with the slider;  it changes only when the mouse button is released.

.IP [4]

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.

If the button is held down, the action auto-repeats.

.IP [5]

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.

If the button is held down, the action auto-repeats.

.IP [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.

.IP [7]

If button 1 is pressed with the Control key down, then if the

mouse is over \fBarrow1\fR or \fBtrough1\fR the view changes

to the very top (left) of the document;  if the mouse is over

\fBarrow2\fR or \fBtrough2\fR the view changes

to the very bottom (right) of the document;  if the mouse is

anywhere else then the button press has no effect.

.IP [8]

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 [9]

In vertical scrollbars Control-Up and Control-Down have the same

behavior as mouse clicks over \fBtrough1\fR and \fBtrough2\fR, respectively.

In horizontal scrollbars these keys have no effect.

.IP [10]

In horizontal scrollbars the Up and Down keys have the same behavior

as mouse clicks over \fBarrow1\fR and \fBarrow2\fR, respectively.

In vertical scrollbars these keys have no effect.

.IP [11]

In horizontal scrollbars Control-Up and Control-Down have the same

behavior as mouse clicks over \fBtrough1\fR and \fBtrough2\fR, respectively.

In vertical scrollbars these keys have no effect.

.IP [12]

The Prior and Next keys have the same behavior

as mouse clicks over \fBtrough1\fR and \fBtrough2\fR, respectively.

.IP [13]

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

.IP [14]

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

.SH KEYWORDS

scrollbar, widget