scale(n) Tk Built-In Commands scale(n)
scale - Create and manipulate scale widgets
scale pathName ?options?
-activebackground -foreground -relief
-background -highlightbackground -repeatdelay
-borderwidth -highlightcolor -repeatinterval
-cursor -highlightthickness -takefocus
-font -orient -troughcolor
See the options manual entry for details on the standard options.
[-bigincrement bigIncrement] Some interactions with the scale cause its value to change by
``large'' increments; this option specifies the size of the large increments. If speci-
fied as 0, the large increments default to 1/10 the range of the scale. [-command com-
mand] Specifies the prefix of a Tcl command to invoke whenever the scale's value is
changed via a widget command. The actual command consists of this option followed by a
space and a real number indicating the new value of the scale. [-digits digits] An inte-
ger specifying how many significant digits should be retained when converting the value of
the scale to a string. If the number is less than or equal to zero, then the scale picks
the smallest value that guarantees that every possible slider position prints as a differ-
ent string. [-from from] A real value corresponding to the left or top end of the scale.
[-label label] A string to display as a label for the scale. For vertical scales the
label is displayed just to the right of the top end of the scale. For horizontal scales
the label is displayed just above the left end of the scale. If the option is specified
as an empty string, no label is displayed. [-length length] Specifies the desired long
dimension of the scale in screen units (i.e. any of the forms acceptable to Tk_GetPixels).
For vertical scales this is the scale's height; for horizontal scales it is the scale's
width. [-resolution resolution] A real value specifying the resolution for the scale. If
this value is greater than zero then the scale's value will always be rounded to an even
multiple of this value, as will tick marks and the endpoints of the scale. If the value
is less than zero then no rounding occurs. Defaults to 1 (i.e., the value will be inte-
gral). [-showvalue showValue] Specifies a boolean value indicating whether or not the
current value of the scale is to be displayed. [-sliderlength sliderLength] Specfies the
size of the slider, measured in screen units along the slider's long dimension. The value
may be specified in any of the forms acceptable to Tk_GetPixels. [-sliderrelief sliderRe-
lief] Specifies the relief to use when drawing the slider, such as raised or sunken.
[-state state] Specifies one of three states for the scale: normal, active, or disabled.
If the scale is disabled then the value may not be changed and the scale won't activate.
If the scale is active, the slider is displayed using the color specified by the active-
Background option. [-tickinterval tickInterval] Must be a real value. Determines the
spacing between numerical tick marks displayed below or to the left of the slider. If 0,
no tick marks will be displayed. [-to to] Specifies a real value corresponding to the
right or bottom end of the scale. This value may be either less than or greater than the
from option. [-variable variable] Specifies the name of a global variable to link to the
scale. Whenever the value of the variable changes, the scale will update to reflect this
value. Whenever the scale is manipulated interactively, the variable will be modified to
reflect the scale's new value. [-width width] Specifies the desired narrow dimension of
the trough in screen units (i.e. any of the forms acceptable to Tk_GetPixels). For verti-
cal scales this is the trough's width; for horizontal scales this is the trough's height.
The scale command creates a new window (given by the pathName argument) and makes it into
a scale widget. Additional options, described above, may be specified on the command line
or in the option database to configure aspects of the scale such as its colors, orienta-
tion, and relief. The scale command returns its pathName argument. At the time this com-
mand is invoked, there must not exist a window named pathName, but pathName's parent must
A scale is a widget that displays a rectangular trough and a small slider. The trough
corresponds to a range of real values (determined by the from, to, and resolution
options), and the position of the slider selects a particular real value. The slider's
position (and hence the scale's value) may be adjusted with the mouse or keyboard as
described in the BINDINGS section below. Whenever the scale's value is changed, a Tcl
command is invoked (using the command option) to notify other interested widgets of the
change. In addition, the value of the scale can be linked to a Tcl variable (using the
variable option), so that changes in either are reflected in the other.
Three annotations may be displayed in a scale widget: a label appearing at the top right
of the widget (top left for horizontal scales), a number displayed just to the left of the
slider (just above the slider for horizontal scales), and a collection of numerical tick
marks just to the left of the current value (just below the trough for horizontal scales).
Each of these three annotations may be enabled or disabled using the configuration
The scale 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 scale widgets:
pathName cget option
Returns the current value of the configuration option given by option. Option may
have any of the values accepted by the scale command.
pathName configure ?option? ?value option value ...?
Query or modify the configuration options of the widget. If no option is speci-
fied, 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 speci-
fied 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 scale command.
pathName coords ?value?
Returns a list whose elements are the x and y coordinates of the point along the
centerline of the trough that corresponds to value. If value is omitted then the
scale's current value is used.
pathName get ?x y?
If x and y are omitted, returns the current value of the scale. If x and y are
specified, they give pixel coordinates within the widget; the command returns the
scale value corresponding to the given pixel. Only one of x or y is used: for
horizontal scales y is ignored, and for vertical scales x is ignored.
pathName identify x y
Returns a string indicating what part of the scale lies under the coordinates given
by x and y. A return value of slider means that the point is over the slider;
trough1 means that the point is over the portion of the slider above or to the
left of the slider; and trough2 means that the point is over the portion of the
slider below or to the right of the slider. If the point isn't over one of these
elements, an empty string is returned.
pathName set value
This command is invoked to change the current value of the scale, and hence the
position at which the slider is displayed. Value gives the new value for the
scale. The command has no effect if the scale is disabled.
Tk automatically creates class bindings for scales that give them the following default
behavior. Where the behavior is different for vertical and horizontal scales, the hori-
zontal behavior is described in parentheses.
 If button 1 is pressed in the trough, the scale's value will be incremented or
decremented by the value of the resolution option so that the slider moves in the
direction of the cursor. If the button is held down, the action auto-repeats.
 If button 1 is pressed over the slider, the slider can be dragged with the mouse.
 If button 1 is pressed in the trough with the Control key down, the slider moves
all the way to the end of its range, in the direction towards the mouse cursor.
 If button 2 is pressed, the scale's value is set to the mouse position. If the
mouse is dragged with button 2 down, the scale's value changes with the drag.
 The Up and Left keys move the slider up (left) by the value of the resolution
 The Down and Right keys move the slider down (right) by the value of the resolution
 Control-Up and Control-Left move the slider up (left) by the value of the bigIncre-
 Control-Down and Control-Right move the slider down (right) by the value of the
 Home moves the slider to the top (left) end of its range.
 End moves the slider to the bottom (right) end of its range.
If the scale is disabled using the state option then none of the above bindings have any
The behavior of scales can be changed by defining new bindings for individual widgets or
by redefining the class bindings.
scale, slider, trough, widget
Tk 4.1 scale(n)