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