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.
Database Name: bigIncrement
Database Class: BigIncrement
Some interactions with the scale cause its value to change by
``large'' increments; this option specifies the size of the
large increments. If specified as 0, the large increments
default to 1/10 the range of the scale.
Database Name: command
Database Class: Command
Specifies the prefix of a Tcl command to invoke whenever the
scale's value is changed via a widget command. The actual com-
mand consists of this option followed by a space and a real num-
ber indicating the new value of the scale.
Database Name: digits
Database Class: Digits
An integer 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 different string.
Database Name: from
Database Class: From
A real value corresponding to the left or top end of the scale.
Database Name: label
Database Class: 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.
Database Name: length
Database Class: 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.
Database Name: resolution
Database Class: 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
Database Name: showValue
Database Class: ShowValue
Specifies a boolean value indicating whether or not the current
value of the scale is to be displayed.
Database Name: sliderLength
Database Class: 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.
Database Name: sliderRelief
Database Class: SliderRelief
Specifies the relief to use when drawing the slider, such as
raised or sunken.
Database Name: state
Database Class: 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-
Database Name: tickInterval
Database Class: 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.
Database Name: to
Database Class: 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.
Database Name: variable
Database Class: 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.
Database Name: width
Database Class: Width
Specifies the desired narrow dimension of the trough in screen
units (i.e. any of the forms acceptable to Tk_GetPixels). For
vertical 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 con-
figure aspects of the scale such as its colors, orientation, and
relief. The scale 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 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 appear-
ing 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 options.
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
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 infor-
mation 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 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
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 verti-
cal and horizontal scales, the horizontal behavior is described in
 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 option.
 The Down and Right keys move the slider down (right) by the
value of the resolution option.
 Control-Up and Control-Left move the slider up (left) by the
value of the bigIncrement option.
 Control-Down and Control-Right move the slider down (right) by
the value of the bigIncrement option.
 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 effect.
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)