Provided by: tk8.6-doc_8.6.13-2_all 
NAME
scrollbar - Create and manipulate 'scrollbar' scrolling control and indicator widgets
SYNOPSIS
scrollbar pathName ?options?
STANDARD OPTIONS
-activebackground -highlightcolor -repeatdelay
-background -highlightthickness -repeatinterval
-borderwidth -jump -takefocus
-cursor -orient -troughcolor
-highlightbackground -relief
See the options manual entry for details on the standard options.
WIDGET-SPECIFIC OPTIONS
Command-Line Name:-activerelief
Database Name: activeRelief
Database Class: 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-Line Name:-command
Database Name: command
Database Class: 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 .t xview or .t yview, consisting of the name of a widget
and either xview (if the scrollbar is for horizontal scrolling) or yview (for
vertical scrolling). All scrollable widgets have xview and yview commands that
take exactly the additional arguments appended by the scrollbar as described in
SCROLLING COMMANDS below.
Command-Line Name:-elementborderwidth
Database Name: elementBorderWidth
Database Class: 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
Tk_GetPixels. If this value is less than zero, the value of the -borderwidth
option is used in its place.
Command-Line Name:-width
Database Name: width
Database Class: 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.
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DESCRIPTION
The scrollbar command creates a new window (given by the pathName 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 scrollbar command returns its pathName argument. At
the time this command is invoked, there must not exist a window 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 a 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 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 associated 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 ...?
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 if no element 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 available 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
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 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 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.
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 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.
pathName get
Returns the scrollbar settings in the form of a list whose elements 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 pixel coordinates 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
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 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 command 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 document, 0.333 refers to a point one-third of the way through the document,
and so on.
prefix scroll number units
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 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 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 COMMAND SYNTAX
In versions of Tk before 4.0, the set and get widget commands used a different form. This
form is still supported for backward compatibility, but it is deprecated. In the old
command syntax, the set widget command has the following form:
pathName 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 command returns a list of four integers, consisting of
the totalUnits, windowUnits, firstUnit, and lastUnit values from the last set 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 widget command.
The most recent set 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.
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 does not 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.
EXAMPLE
Create a window with a scrollable text widget:
toplevel .tl
text .tl.t -yscrollcommand {.tl.s set}
scrollbar .tl.s -command {.tl.t yview}
grid .tl.t .tl.s -sticky nsew
grid columnconfigure .tl 0 -weight 1
grid rowconfigure .tl 0 -weight 1
SEE ALSO
ttk:scrollbar(3tk)
KEYWORDS
scrollbar, widget