1Scale(3)              User Contributed Perl Documentation             Scale(3)
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NAME

6       Tk::Scale - Create and manipulate Scale widgets
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SYNOPSIS

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

12       -activebackground   -font     -highlightthickness -repeatinterval
13       -background    -foreground    -orient   -takefocus
14       -borderwidth   -highlightbackground     -relief   -troughcolor
15       -cursor   -highlightcolor     -repeatdelay
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17       See Tk::options for details of the standard options.
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WIDGET-SPECIFIC OPTIONS

20       Name:     bigIncrement
21       Class:    BigIncrement
22       Switch:   -bigincrement
23           Some interactions with the scale cause its value to change by
24           ``large'' increments;  this option specifies the size of the large
25           increments.  If specified as 0, the large increments default to
26           1/10 the range of the scale.
27
28       Name:     command
29       Class:    Command
30       Switch:   -command
31           Specifies the prefix of a perl/Tk callback to invoke whenever the
32           scale's value is changed via a method.  The actual command consists
33           of this option followed by a space and a real number indicating the
34           new value of the scale.
35
36       Name:     digits
37       Class:    Digits
38       Switch:   -digits
39           An integer specifying how many significant digits should be
40           retained when converting the value of the scale to a string.  If
41           the number is less than or equal to zero, then the scale picks the
42           smallest value that guarantees that every possible slider position
43           prints as a different string.
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45       Name:     from
46       Class:    From
47       Switch:   -from
48           A real value corresponding to the left or top end of the scale.
49
50       Name:     label
51       Class:    Label
52       Switch:   -label
53           A string to display as a label for the scale.  For vertical scales
54           the label is displayed just to the right of the top end of the
55           scale.  For horizontal scales the label is displayed just above the
56           left end of the scale.  If the option is specified as an empty
57           string, no label is displayed.
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59       Name:     length
60       Class:    Length
61       Switch:   -length
62           Specifies the desired long dimension of the scale in screen units
63           (i.e. any of the forms acceptable to Tk_GetPixels).  For vertical
64           scales this is the scale's height;  for horizontal scales it is the
65           scale's width.
66
67       Name:     resolution
68       Class:    Resolution
69       Switch:   -resolution
70           A real value specifying the resolution for the scale.  If this
71           value is greater than zero then the scale's value will always be
72           rounded to an even multiple of this value, as will tick marks and
73           the endpoints of the scale.  If the value is less than zero then no
74           rounding occurs.  Defaults to 1 (i.e., the value will be integral).
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76       Name:     showValue
77       Class:    ShowValue
78       Switch:   -showvalue
79           Specifies a boolean value indicating whether or not the current
80           value of the scale is to be displayed.
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82       Name:     sliderLength
83       Class:    SliderLength
84       Switch:   -sliderlength
85           Specfies the size of the slider, measured in screen units along the
86           slider's long dimension.  The value may be specified in any of the
87           forms acceptable to Tk_GetPixels.
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89       Name:     sliderRelief
90       Class:    SliderRelief
91       Switch:   -sliderrelief
92           Specifies the relief to use when drawing the slider, such as raised
93           or sunken.
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95       Name:     state
96       Class:    State
97       Switch:   -state
98           Specifies one of three states for the scale:  normal, active, or
99           disabled.  If the scale is disabled then the value may not be
100           changed and the scale won't activate.  If the scale is active, the
101           slider is displayed using the color specified by the
102           activeBackground option.
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104       Name:     tickInterval
105       Class:    TickInterval
106       Switch:   -tickinterval
107           Must be a real value.  Determines the spacing between numerical
108           tick marks displayed below or to the left of the slider.  If 0, no
109           tick marks will be displayed.
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111       Name:     to
112       Class:    To
113       Switch:   -to
114           Specifies a real value corresponding to the right or bottom end of
115           the scale.  This value may be either less than or greater than the
116           from option.
117
118       Name:     variable
119       Class:    Variable
120       Switch:   -variable
121           Specifies the name of a global variable to link to the scale.
122           Whenever the value of the variable changes, the scale will update
123           to reflect this value.  Whenever the scale is manipulated
124           interactively, the variable will be modified to reflect the scale's
125           new value.
126
127       Name:     width
128       Class:    Width
129       Switch:   -width
130           Specifies the desired narrow dimension of the trough in screen
131           units (i.e. any of the forms acceptable to Tk_GetPixels).  For
132           vertical scales this is the trough's width;  for horizontal scales
133           this is the trough's height.
134

DESCRIPTION

136       The Scale method creates a new window (given by the $widget argument)
137       and makes it into a scale widget.  Additional options, described above,
138       may be specified on the command line or in the option database to
139       configure aspects of the scale such as its colors, orientation, and
140       relief.  The scale command returns its $widget argument.  At the time
141       this command is invoked, there must not exist a window named $widget,
142       but $widget's parent must exist.
143
144       A scale is a widget that displays a rectangular trough and a small
145       slider.  The trough corresponds to a range of real values (determined
146       by the from, to, and resolution options), and the position of the
147       slider selects a particular real value.  The slider's position (and
148       hence the scale's value) may be adjusted with the mouse or keyboard as
149       described in the "BINDINGS" section below.  Whenever the scale's value
150       is changed, a Tcl command is invoked (using the command option) to
151       notify other interested widgets of the change.  In addition, the value
152       of the scale can be linked to a Tcl variable (using the variable
153       option), so that changes in either are reflected in the other.
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155       Three annotations may be displayed in a scale widget:  a label
156       appearing at the top right of the widget (top left for horizontal
157       scales), a number displayed just to the left of the slider (just above
158       the slider for horizontal scales), and a collection of numerical tick
159       marks just to the left of the current value (just below the trough for
160       horizontal scales).  Each of these three annotations may be enabled or
161       disabled using the configuration options.
162

WIDGET METHODS

164       The Scale method creates a widget object.  This object supports the
165       configure and cget methods described in Tk::options which can be used
166       to enquire and modify the options described above.  The widget also
167       inherits all the methods provided by the generic Tk::Widget class.
168
169       The following additional methods are available for scale widgets:
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171       $scale->coords(?value?)
172           Returns a list whose elements are the x and y coordinates of the
173           point along the centerline of the trough that corresponds to value.
174           If value is omitted then the scale's current value is used.
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176       $scale->get(?x, y?)
177           If x and y are omitted, returns the current value of the scale.  If
178           x and y are specified, they give pixel coordinates within the
179           widget;  the command returns the scale value corresponding to the
180           given pixel.  Only one of x or y is used:  for horizontal scales y
181           is ignored, and for vertical scales x is ignored.
182
183       $scale->identify(x, y)
184           Returns a string indicating what part of the scale lies under the
185           coordinates given by x and y.  A return value of slider means that
186           the point is over the slider;  trough1 means that the point is over
187           the portion of the slider above  or to the left of the slider; and
188           trough2 means that the point is over the portion of the slider
189           below or to the right of the slider.  If the point isn't over one
190           of these elements, an empty string is returned.
191
192       $scale->set(value)
193           This command is invoked to change the current value of the scale,
194           and hence the position at which the slider is displayed.  Value
195           gives the new value for the scale.  The command has no effect if
196           the scale is disabled.
197

BINDINGS

199       Tk automatically creates class bindings for scales that give them the
200       following default behavior.  Where the behavior is different for
201       vertical and horizontal scales, the horizontal behavior is described in
202       parentheses.
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204       [1] If button 1 is pressed in the trough, the scale's value will be
205           incremented or decremented by the value of the resolution option so
206           that the slider moves in the direction of the cursor.  If the
207           button is held down, the action auto-repeats.
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209       [2] If button 1 is pressed over the slider, the slider can be dragged
210           with the mouse.
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212       [3] If button 1 is pressed in the trough with the Control key down, the
213           slider moves all the way to the end of its range, in the direction
214           towards the mouse cursor.
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216       [4] If button 2 is pressed, the scale's value is set to the mouse
217           position.  If the mouse is dragged with button 2 down, the scale's
218           value changes with the drag.
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220       [5] The Up and Left keys move the slider up (left) by the value of the
221           resolution option.
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223       [6] The Down and Right keys move the slider down (right) by the value
224           of the resolution option.
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226       [7] Control-Up and Control-Left move the slider up (left) by the value
227           of the bigIncrement option.
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229       [8] Control-Down and Control-Right move the slider down (right) by the
230           value of the bigIncrement option.
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232       [9] Home moves the slider to the top (left) end of its range.
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234       [10]
235           End moves the slider to the bottom (right) end of its range.
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237           If the scale is disabled using the state option then none of the
238           above bindings have any effect.
239
240           The behavior of scales can be changed by defining new bindings for
241           individual widgets or by redefining the class bindings.
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KEYWORDS

244       scale, slider, trough, widget
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248perl v5.28.1                      2019-02-12                          Scale(3)
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