scale(n) Tk (4.1) scale(n)
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NAME
scale - Create and manipulate scale widgets
SYNOPSIS
scale 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 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
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scale(n) Tk (4.1) scale(n)
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
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
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scale(n) Tk (4.1) scale(n)
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 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 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.
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scale(n) Tk (4.1) scale(n)
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
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scale(n) Tk (4.1) scale(n)
(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
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
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scale(n) Tk (4.1) scale(n)
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
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