scale - Create and manipulate scale widgets
-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.
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.
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.
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. [-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
Specifies the desired long dimension of the scale in
screen units (i.e. any of the forms acceptable to Tk_GetPixels
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
integral). [-showvalue showValue]
Specifies a boolean value indicating whether or not the current value of the
scale is to be displayed. [-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
the relief to use when drawing the slider, such as raised
. [-state state]
one of three states for the scale: normal
. 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
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.
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
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.
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.
command returns its pathName
argument. At the time
this command is invoked, there must not exist a window named pathName
's parent must exist.
A scale is a widget that displays a rectangular trough
and a small
. The trough corresponds to a range of real values (determined by
, 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.
command creates a new Tcl command whose name is
. This command may be used to invoke various operations on the
widget. It has the following general form:
pathName option ?arg arg ...?
and the arg
s 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
- 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
- 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
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 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
- 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
- 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 Up and Left keys move the slider up (left) by the value of the
- The Down and Right keys move the slider down (right) by the value of the
- Control-Up and Control-Left move the slider up (left) by the value of the
- 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