scrollbar - Create and manipulate 'scrollbar' scrolling control and indicator
widgets
scrollbar pathName ?
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.
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.
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.
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.
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.
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.
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.
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.
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
ttk:scrollbar(3tk)
scrollbar, widget