NAME

       Tk::Scale - Create and manipulate Scale widgets

SYNOPSIS

       $scale = $parent->Scale(?options?);

STANDARD OPTIONS

       -activebackground   -font     -highlightthickness -repeatinterval
       -background    -foreground    -orient   -takefocus
       -borderwidth   -highlightbackground     -relief   -troughcolor
       -cursor   -highlightcolor     -repeatdelay

       See Tk::options for details of the standard options.

WIDGET-SPECIFIC OPTIONS

       Name:     bigIncrement
       Class:    BigIncrement
       Switch:   -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.

       Name:     command
       Class:    Command
       Switch:   -command
           Specifies the prefix of a perl/Tk callback to invoke whenever the scale's value is
           changed via a method.  The actual command consists of this option followed by a space
           and a real number indicating the new value of the scale.

       Name:     digits
       Class:    Digits
       Switch:   -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.

       Name:     from
       Class:    From
       Switch:   -from
           A real value corresponding to the left or top end of the scale.

       Name:     label
       Class:    Label
       Switch:   -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.

       Name:     length
       Class:    Length
       Switch:   -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.

       Name:     resolution
       Class:    Resolution
       Switch:   -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).

       Name:     showValue
       Class:    ShowValue
       Switch:   -showvalue
           Specifies a boolean value indicating whether or not the current value of the scale is
           to be displayed.

       Name:     sliderLength
       Class:    SliderLength
       Switch:   -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.

       Name:     sliderRelief
       Class:    SliderRelief
       Switch:   -sliderrelief
           Specifies the relief to use when drawing the slider, such as raised or sunken.

       Name:     state
       Class:    State
       Switch:   -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.

       Name:     tickInterval
       Class:    TickInterval
       Switch:   -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.

       Name:     to
       Class:    To
       Switch:   -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.

       Name:     variable
       Class:    Variable
       Switch:   -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.

       Name:     width
       Class:    Width
       Switch:   -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 method creates a new window (given by the $widget 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 $widget argument.  At the time
       this command is invoked, there must not exist a window named $widget, but $widget'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 METHODS

       The Scale method creates a widget object.  This object supports the configure and cget
       methods described in Tk::options which can be used to enquire and modify the options
       described above.  The widget also inherits all the methods provided by the generic
       Tk::Widget class.

       The following additional methods are available for scale widgets:

       $scale->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.

       $scale->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.

       $scale->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.

       $scale->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