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

6       Tk::Scrollbar - Create and manipulate Scrollbar widgets
7

SYNOPSIS

9       $scrollbar = $parent->Scrollbar(?options?);
10

STANDARD OPTIONS

12       -activebackground   -highlightbackground     -orient   -takefocus
13       -background    -highlightcolor     -relief   -troughcolor
14       -borderwidth   -highlightthickness -repeatdelay
15       -cursor   -jump     -repeatinterval
16
17       See Tk::options for details of the standard options.
18

WIDGET-SPECIFIC OPTIONS

20       Name:     activeRelief
21       Class:    ActiveRelief
22       Switch:   -activerelief
23           Specifies the relief to use when displaying the element that is
24           active, if any.  Elements other than the active element are always
25           displayed with a raised relief.
26
27       Name:     command
28       Class:    Command
29       Switch:   -command
30           Specifies a callback to invoke to change the view in the widget
31           associated with the scrollbar.  When a user requests a view change
32           by manipulating the scrollbar, the callback is invoked.  The
33           callback is passed additional arguments as described later. This
34           option almost always has a value such as [xview => $widget] or
35           [yview => $widget], consisting of the a widget object and either
36           xview (if the scrollbar is for horizontal scrolling) or yview (for
37           vertical scrolling).  All scrollable widgets have xview and yview
38           methods that take exactly the additional arguments appended by the
39           scrollbar as described in "SCROLLING COMMANDS" below.
40
41       Name:     elementBorderWidth
42       Class:    BorderWidth
43       Switch:   -elementborderwidth
44           Specifies the width of borders drawn around the internal elements
45           of the scrollbar (the two arrows and the slider).  The value may
46           have any of the forms acceptable to Tk_GetPixels.  If this value is
47           less than zero, the value of the borderWidth option is used in its
48           place.
49
50       Name:     width
51       Class:    Width
52       Switch:   -width
53           Specifies the desired narrow dimension of the scrollbar window, not
54           including 3-D border, if any.  For vertical scrollbars this will be
55           the width and for horizontal scrollbars this will be the height.
56           The value may have any of the forms acceptable to Tk_GetPixels.
57

DESCRIPTION

59       The Scrollbar method creates a new window (given by the $widget
60       argument) and makes it into a scrollbar widget.  Additional options,
61       described above, may be specified on the command line or in the option
62       database to configure aspects of the scrollbar such as its colors,
63       orientation, and relief.  The scrollbar command returns its $widget
64       argument.  At the time this command is invoked, there must not exist a
65       window named $widget, but $widget's parent must exist.
66
67       A scrollbar is a widget that displays two arrows, one at each end of
68       the scrollbar, and a slider in the middle portion of the scrollbar.  It
69       provides information about what is visible in an associated window that
70       displays an document of some sort (such as a file being edited or a
71       drawing).  The position and size of the slider indicate which portion
72       of the document is visible in the associated window.  For example, if
73       the slider in a vertical scrollbar covers the top third of the area
74       between the two arrows, it means that the associated window displays
75       the top third of its document.
76
77       Scrollbars can be used to adjust the view in the associated window by
78       clicking or dragging with the mouse.  See "BINDINGS" below for details.
79

ELEMENTS

81       A scrollbar displays five elements, which are referred to in the
82       methods for the scrollbar:
83
84       arrow1
85           The top or left arrow in the scrollbar.
86
87       trough1
88           The region between the slider and arrow1.
89
90       slider
91           The rectangle that indicates what is visible in the associated
92           widget.
93
94       trough2
95           The region between the slider and arrow2.
96
97       arrow2
98           The bottom or right arrow in the scrollbar.
99

WIDGET METHODS

101       The Scrollbar method creates a widget object.  This object supports the
102       configure and cget methods described in Tk::options which can be used
103       to enquire and modify the options described above.  The widget also
104       inherits all the methods provided by the generic Tk::Widget class.
105
106       The following additional methods are available for scrollbar widgets:
107
108       $scrollbar->activate(?element?)
109           Marks the element indicated by element as active, which causes it
110           to be displayed as specified by the activeBackground and
111           activeRelief options.  The only element values understood by this
112           command are arrow1, slider, or arrow2.  If any other value is
113           specified then no element of the scrollbar will be active.  If
114           element is not specified, the command returns the name of the
115           element that is currently active, or an empty string if no element
116           is active.
117
118       $scrollbar->delta(deltaX, deltaY)
119           Returns a real number indicating the fractional change in the
120           scrollbar setting that corresponds to a given change in slider
121           position.  For example, if the scrollbar is horizontal, the result
122           indicates how much the scrollbar setting must change to move the
123           slider deltaX pixels to the right (deltaY is ignored in this case).
124           If the scrollbar is vertical, the result indicates how much the
125           scrollbar setting must change to move the slider deltaY pixels
126           down.  The arguments and the result may be zero or negative.
127
128       $scrollbar->fraction(x, y)
129           Returns a real number between 0 and 1 indicating where the point
130           given by x and y lies in the trough area of the scrollbar.  The
131           value 0 corresponds to the top or left of the trough, the value 1
132           corresponds to the bottom or right, 0.5 corresponds to the middle,
133           and so on.  X and y must be pixel coordinates relative to the
134           scrollbar widget.  If x and y refer to a point outside the trough,
135           the closest point in the trough is used.
136
137       $scrollbar->get
138           Returns the scrollbar settings in the form of a list whose elements
139           are the arguments to the most recent set method.
140
141       $scrollbar->identify(x, y)
142           Returns the name of the element under the point given by x and y
143           (such as arrow1), or an empty string if the point does not lie in
144           any element of the scrollbar.  X and y must be pixel coordinates
145           relative to the scrollbar widget.
146
147       $scrollbar->set(first, last)
148           This command is invoked by the scrollbar's associated widget to
149           tell the scrollbar about the current view in the widget.  The
150           command takes two arguments, each of which is a real fraction
151           between 0 and 1.  The fractions describe the range of the document
152           that is visible in the associated widget.  For example, if first is
153           0.2 and last is 0.4, it means that the first part of the document
154           visible in the window is 20% of the way through the document, and
155           the last visible part is 40% of the way through.
156

SCROLLING COMMANDS

158       When the user interacts with the scrollbar, for example by dragging the
159       slider, the scrollbar notifies the associated widget that it must
160       change its view.  The scrollbar makes the notification by evaluating a
161       callback specified as the scrollbar's -command option.  The callback
162       may take several forms.  In each case, the intial arguments passed are
163       those specified in the -command callback itself, which usually has a
164       form like [yview => $widget].  (Which will invoke $widget->yview(...)
165       where the ... part is as below. See Tk::callbacks for details.)  The
166       callback is passed additional arguments as follows:
167
168       moveto,fraction
169           Fraction is a real number between 0 and 1.  The widget should
170           adjust its view so that the point given by fraction appears at the
171           beginning of the widget.  If fraction is 0 it refers to the
172           beginning of the document.  1.0 refers to the end of the document,
173           0.333 refers to a point one-third of the way through the document,
174           and so on.
175
176       scroll,number,units
177           The widget should adjust its view by number units.  The units are
178           defined in whatever way makes sense for the widget, such as
179           characters or lines in a text widget.  Number is either 1, which
180           means one unit should scroll off the top or left of the window, or
181           -1, which means that one unit should scroll off the bottom or right
182           of the window.
183
184       scroll,number,page
185           The widget should adjust its view by number pages.  It is up to the
186           widget to define the meaning of a page;  typically it is slightly
187           less than what fits in the window, so that there is a slight
188           overlap between the old and new views.  Number is either 1, which
189           means the next page should become visible, or -1, which means that
190           the previous page should become visible.
191

OLD COMMAND SYNTAX

193       In versions of Tk before 4.0, the set and get widget commands used a
194       different form.  This form is still supported for backward
195       compatibility, but it is deprecated.  In the old command syntax, the
196       set method has the following form:
197
198       $scrollbar->set(totalUnits, windowUnits, firstUnit, lastUnit)
199           In this form the arguments are all integers.  TotalUnits gives the
200           total size of the object being displayed in the associated widget.
201           The meaning of one unit depends on the associated widget;  for
202           example, in a text editor widget units might correspond to lines of
203           text.  WindowUnits indicates the total number of units that can fit
204           in the associated window at one time.  FirstUnit and lastUnit give
205           the indices of the first and last units currently visible in the
206           associated window (zero corresponds to the first unit of the
207           object).
208
209       Under the old syntax the get method returns a list of four integers,
210       consisting of the totalUnits, windowUnits, firstUnit, and lastUnit
211       values from the last set method.
212
213       The callbacks generated by scrollbars also have a different form when
214       the old syntax is being used, the callback is passed a single argument:
215
216       unit
217           Unit is an integer that indicates what should appear at the top or
218           left of the associated widget's window.  It has the same meaning as
219           the firstUnit and lastUnit arguments to the set method.
220
221       The most recent set method determines whether or not to use the old
222       syntax.  If it is given two real arguments then the new syntax will be
223       used in the future, and if it is given four integer arguments then the
224       old syntax will be used.
225

BINDINGS

227       Tk automatically creates class bindings for scrollbars that give them
228       the following default behavior.  If the behavior is different for
229       vertical and horizontal scrollbars, the horizontal behavior is
230       described in parentheses.
231
232       [1] Pressing button 1 over arrow1 causes the view in the associated
233           widget to shift up (left) by one unit so that the document appears
234           to move down (right) one unit.  If the button is held down, the
235           action auto-repeats.
236
237       [2] Pressing button 1 over trough1 causes the view in the associated
238           widget to shift up (left) by one screenful so that the document
239           appears to move down (right) one screenful.  If the button is held
240           down, the action auto-repeats.
241
242       [3] Pressing button 1 over the slider and dragging causes the view to
243           drag with the slider.  If the jump option is true, then the view
244           doesn't drag along with the slider;  it changes only when the mouse
245           button is released.
246
247       [4] Pressing button 1 over trough2 causes the view in the associated
248           widget to shift down (right) by one screenful so that the document
249           appears to move up (left) one screenful.  If the button is held
250           down, the action auto-repeats.
251
252       [5] Pressing button 1 over arrow2 causes the view in the associated
253           widget to shift down (right) by one unit so that the document
254           appears to move up (left) one unit.  If the button is held down,
255           the action auto-repeats.
256
257       [6] If button 2 is pressed over the trough or the slider, it sets the
258           view to correspond to the mouse position;  dragging the mouse with
259           button 2 down causes the view to drag with the mouse.  If button 2
260           is pressed over one of the arrows, it causes the same behavior as
261           pressing button 1.
262
263       [7] If button 1 is pressed with the Control key down, then if the mouse
264           is over arrow1 or trough1 the view changes to the very top (left)
265           of the document;  if the mouse is over arrow2 or trough2 the view
266           changes to the very bottom (right) of the document;  if the mouse
267           is anywhere else then the button press has no effect.
268
269       [8] In vertical scrollbars the Up and Down keys have the same behavior
270           as mouse clicks over arrow1 and arrow2, respectively.  In
271           horizontal scrollbars these keys have no effect.
272
273       [9] In vertical scrollbars Control-Up and Control-Down have the same
274           behavior as mouse clicks over trough1 and trough2, respectively.
275           In horizontal scrollbars these keys have no effect.
276
277       [10]
278           In horizontal scrollbars the Up and Down keys have the same
279           behavior as mouse clicks over arrow1 and arrow2, respectively.  In
280           vertical scrollbars these keys have no effect.
281
282       [11]
283           In horizontal scrollbars Control-Up and Control-Down have the same
284           behavior as mouse clicks over trough1 and trough2, respectively.
285           In vertical scrollbars these keys have no effect.
286
287       [12]
288           The Prior and Next keys have the same behavior as mouse clicks over
289           trough1 and trough2, respectively.
290
291       [13]
292           The Home key adjusts the view to the top (left edge) of the
293           document.
294
295       [14]
296           The End key adjusts the view to the bottom (right edge) of the
297           document.
298

SEE ALSO

300       Tk::callbacks Tk::Scrolled
301

KEYWORDS

303       scrollbar, widget
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307perl v5.28.1                      2019-02-12                      Scrollbar(3)
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