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Scale(3)              User Contributed Perl Documentation             Scale(3)




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


POD ERRORS

       Hey! The above document had some coding errors, which are explained
       below:

       Around line 48:
           alternative text 'perl/Tk callback' contains non-escaped | or /



perl v5.18.0                      2010-05-29                          Scale(3)

perl-Tk 804.030_502 - Generated Fri Aug 16 08:32:19 CDT 2013
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