1Adjuster(3) User Contributed Perl Documentation Adjuster(3)
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6 Tk::Adjuster - Allow size of packed widgets to be adjusted by user
7
9 use Tk::Adjuster;
10 $adjuster = $widget->Adjuster(?options?);
12
14 Name: restore
15 Class: Restore
16 Switch: -restore
17 Specifies a boolean value that determines whether the Adjuster
18 should forcibly attempt to make room for itself (by reducing the
19 size of its managed widget) when it is unmapped (for example, due
20 to a size change in a top level window). The default value is 1.
21 Name: side
23 Class: Side
24 Switch: -side
25 Specifies the side on which the managed widget lies relative to the
26 Adjuster. In conjunction with the pack geometry manager, this
27 relates to the side of the master against which the managed widget
28 and the Adjuster are packed. Must be left, right, top, or bottom.
29 Defaults to top.
30 Name: widget
32 Class: Widget
33 Switch: -widget
34 Specifies the widget which is to be managed by the Adjuster.
35
37 Tk::Adjuster is a Frame containing a "line" and a "blob".
38 Dragging with Mouse Button-1 results in a line being dragged to
40 indicate new size. Releasing Button-1 submits GeometryRequests on
41 behalf of the managed widget which will cause the packer to change the
42 widget's size.
43 If Drag is done with Shift button down, then GeometryRequests are made
45 in "real time" so that text-flow effects can be seen, but as a lot more
46 work is done behaviour may be sluggish.
47 If widget is packed with -side => left or -side => right then width is
49 adjusted. If packed -side => top or -side => bottom then height is
50 adjusted.
51 packPropagate is turned off for the master window to prevent adjustment
53 changing overall window size. Similarly packPropagate is turned off for
54 the managed widget if it has things packed inside it. This is so that
55 the GeometryRequests made by Tk::Adjuster are not overridden by pack.
56 In addition, the managed widget is made non-expandable to prevent the
58 geometry manager reallocating freed space in the master back to the
59 managed widget. Note however that expansion is turned off only after
60 the Adjuster is mapped, which allows the managed widget to expand
61 naturally on window creation.
62 The Tk::Widget method, packAdjust, calls pack on the widget, then
64 creates an instance of Tk::Adjuster, and packs that "after" the widget.
65 Its use has two disadvantages however: the Adjuster widget is not made
66 available to the caller, and options cannot be set on the Adjuster. For
67 these reasons, the Tk::Adjuster method, packAfter is preferred, but
68 packAdjust is retained for backwards compatibility.
69
71 $adjuster->packAfter(managed_widget, ?pack_options?)
72 This command configures the Adjuster's -widget and -side options
73 respectively to managed_widget and the -side value specified in
74 pack_options (top if not specified). It then packs the Adjuster
75 after managed_widget, with -fill set to x or y as appropriate.
76 $adjuster->packForget?(boolean)?
78 This command calls Tk::Widget::packForget on the Adjuster. If a
79 parameter is provided and it has a true boolean value, then
80 packForget is also called on the managed widget.
81 $adjuster->slave
83 This command returns the value $adjuster->cget('-widget'), ie. the
84 reference to the managed widget.
85
87 Using an Adjuster to separate two widgets, whereby the left widget is
88 managed, and right widget expands to fill space on a window resize
89 a) Using packAfter (preferred interface)
91 use Tk;
93 use Tk::Adjuster;
94 my $f = MainWindow->new;
96 my $lst1 = $f->Listbox();
97 my $adj1 = $f->Adjuster();
98 my $lst2 = $f->Listbox();
99 my $side = 'left';
101 $lst1->pack(-side => $side, -fill => 'both', -expand => 1);
102 $adj1->packAfter($lst1, -side => $side);
103 $lst2->pack(-side => $side, -fill => 'both', -expand => 1);
104 MainLoop;
105 b) Using packAdjust
107 use Tk;
109 use Tk::Adjuster;
110 my $f = MainWindow->new;
112 my $lst1 = $f->Listbox();
113 my $lst2 = $f->Listbox();
114 my $side = 'left';
116 $lst1->packAdjust(-side => $side, -fill => 'both');
117 $lst2->pack (-side => $side, -fill => 'both', -expand => 1);
118 MainLoop;
119 c) Using the standard Tk::Widget::pack
121 use Tk;
123 use Tk::Adjuster;
124 my $f = MainWindow->new;
126 my $side = 'left';
127 my $lst1 = $f->Listbox();
128 my $adj = $f->Adjuster(-widget => $lst1, -side => $side);
129 my $lst2 = $f->Listbox();
130 $lst1->pack(-side => $side, -fill => 'both', -expand => 1);
132 $adj->pack (-side => $side, -fill => 'y');
133 $lst2->pack(-side => $side, -fill => 'both', -expand => 1);
134 MainLoop;
136 Changing the above examples so that $side has the value 'right' means
138 the left widget expands to fill space on a window resize.
139 Changing the above examples so that $side has the value 'top' produces
141 a testcase with a horizontal Adjuster. Here the bottom widget expands
142 to fill space on a window resize. Packing to the 'bottom' makes the
143 top widget expand to fill space on window resize.
144 Using -restore => 0 for multiple columns
146 In the case of multiple columns (or rows) the "restore" functionality
148 of the Adjuster can be inconvenient. When the user adjusts the width of
149 one column and thereby pushes the Adjuster of another column off the
150 window, this adjuster tries to restore itself by reducing the size of
151 its managed widget. This has the effect that column widths shrink; and
152 the original size is not restored when the user reverses the
153 originating change. The -restore option can be used to turn off this
154 functionality. (It makes some sense, however, to leave -restore turned
155 on for the first-packed Adjuster, so that at least one Adjuster always
156 remains visible.)
157 use Tk;
159 use Tk::Adjuster;
160 my $f = MainWindow->new;
161 my $lst1 = $f->Listbox();
162 my $adj1 = $f->Adjuster();
163 my $lst2 = $f->Listbox();
164 my $adj2 = $f->Adjuster(-restore => 0);
165 my $lst3 = $f->Listbox();
166 my $side = 'left';
168 $lst1->pack(-side => $side, -fill => 'both', -expand => 1);
169 $adj1->packAfter($lst1, -side => $side);
170 $lst2->pack(-side => $side, -fill => 'both', -expand => 1);
171 $adj2->packAfter($lst2, -side => $side);
172 $lst3->pack(-side => $side, -fill => 'both', -expand => 1);
173 MainLoop;
175
177 It is currently not possible to configure the appearance of the
178 Adjuster. It would be nice to be able to set the width and relief of
179 the Adjuster "line" and the presence/absence of the "blob" on the
180 Adjuster.
181 Tk::Adjuster works theoretically with the grid geometry manager but
183 there are currently some problems which seem to be due to bugs in grid:
184 a) There's never an Unmap event for the adjuster, so the "restore"
186 functionality has no effect.
187 b) After adjusting, widgets protrude into the border of the master.
188 c) grid('Propagate', 0) on MainWindow has no effect - window shrinks/grows
189 when widgets are adjusted.
190 d) Widgets shuffle to correct position on startup
191perl v5.32.0 2020-07-28 Adjuster(3)