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 specified as 0, the large increments default to 1/10 the range of the scale. [-command command] Speci-
fies 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 integer specifying how many sig-
nificant 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. [-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 hor-
izontal 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 integral). [-showvalue show-
Value] Specifies a boolean value indicating whether or not the current value of the scale is to be displayed. [-sliderlength sliderLength]
Specifies 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 sliderRelief] 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 will not activate. If the scale is active, the slider is displayed using the color specified by the
activeBackground 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 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 configure 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 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 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 com-
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 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 is not 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 ver-
tical and horizontal scales, the horizontal 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 direc-
tion 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)