Provided by: tk8.5-doc_8.5.19-3_all 
NAME
scale - Create and manipulate scale widgets
SYNOPSIS
scale pathName ?options?
STANDARD 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.
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 specifies the size of the large increments. If specified 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 indicating 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 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
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.
Command-Line Name:-sliderrelief
Database Name: sliderRelief
Database Class: SliderRelief
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: 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.
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 interactively, 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.
_________________________________________________________________________________________________
DESCRIPTION
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.
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 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.
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 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 Control 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