scale(n) Tk Built-In Commands scale(n)_________________________________________________________________NAMEscale - Create and manipulate scale widgets
SYNOPSISscale pathName ?options?
STANDARD OPTIONS-activebackground-font-highlightthickness-repeatinterval
-background-foreground-orient-takefocus
-borderwidth-highlightbackground-relief-troughcolor
-cursor-highlightcolor-repeatdelay
See the options manual entry for details on the standard
options.
WIDGET-SPECIFIC OPTIONS
Command-Line Name:-bigincrement
Database Name: bigIncrement
Database Class: BigIncrement
Some interactions with the scale cause its value to
change by ``large'' increments; this option speci-
fies the size of the large increments. If speci-
fied as 0, the large increments default to 1/10 the
range of the scale.
Command-Line Name:-command
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 command consists of this
option followed by a space and a real number indi-
cating the new value of the scale.
Command-Line Name:-digits
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.
Command-Line Name:-from
Database Name: from
Database Class: From
A real value corresponding to the left or top end
Tk 4.1 1
scale(n) Tk Built-In Commands scale(n)
of the scale.
Command-Line Name:-label
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.
Command-Line Name:-length
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.
Command-Line Name:-resolution
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 integral).
Command-Line Name:-showvalue
Database Name: showValue
Database Class: ShowValue
Specifies a boolean value indicating whether or not
the current value of the scale is to be displayed.
Command-Line Name:-sliderlength
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.
Command-Line Name:-sliderrelief
Database Name: sliderRelief
Database Class: SliderRelief
Tk 4.1 2
scale(n) Tk Built-In Commands scale(n)
Specifies the relief to use when drawing the
slider, such as raised or sunken.
Command-Line Name:-state
Database Name: state
Database Class: State
Specifies one of three states for the scale: nor-
mal, 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
activeBackground option.
Command-Line Name:-tickinterval
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.
Command-Line Name:-to
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.
Command-Line Name:-variable
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 interac-
tively, the variable will be modified to reflect
the scale's new value.
Command-Line Name:-width
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.
_________________________________________________________________Tk 4.1 3
scale(n) Tk Built-In Commands scale(n)DESCRIPTION
The scale command creates a new window (given by the path-
Name argument) and makes it into a scale widget. Addi-
tional 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 partic-
ular 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.
WIDGET COMMAND
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 specified, returns a list
describing all of the available options for path-
Name (see Tk_ConfigureInfo for information on the
format of this list). If option is specified with
Tk 4.1 4
scale(n) Tk Built-In Commands scale(n)
no value, then the command returns a list describ-
ing the one named option (this list will be identi-
cal 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 coor-
dinates 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.
BINDINGS
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.
[1] 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
Tk 4.1 5
scale(n) Tk Built-In Commands scale(n)
button is held down, the action auto-repeats.
[2] If button 1 is pressed over the slider, the slider
can be dragged with the mouse.
[3] If button 1 is pressed in the trough with the Con-
trol key down, the slider moves all the way to the
end of its range, in the direction towards the
mouse cursor.
[4] 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.
[5] The Up and Left keys move the slider up (left) by
the value of the resolution option.
[6] The Down and Right keys move the slider down
(right) by the value of the resolution option.
[7] Control-Up and Control-Left move the slider up
(left) by the value of the bigIncrement option.
[8] Control-Down and Control-Right move the slider down
(right) by the value of the bigIncrement option.
[9] Home moves the slider to the top (left) end of its
range.
[10] 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.
KEYWORDS
scale, slider, trough, widget
Tk 4.1 6
