Tk::TiedListbox - gang together Listboxes
use Tk::TiedListbox
$l1 = $mw->Listbox(-exportselection => 0,...);
$l2 = $mw->Listbox(-exportselection => 0,...);
$l3 = $mw->Listbox(-exportselection => 0,...);
$l1->tie([$l2,$l3]);
TiedListbox causes two or more Listboxes to be operated in tandem.
One application is emulating multi-column listboxes. The scrolling,
selection, or both mechanisms may be tied together. The methods tie
and untie are provided, along with overridden versions of some of
the Listbox methods to provide tandem operation.
Scrollbars are fully supported. You can use either explicitly created
Scrollbars, the ScrlListbox widget, or the Scrolled
super-widget. Tricks to "attach" multiple tied listboxes to a single
scrollbar are unnecessary and will lead to multiple calls of the
listbox methods (a bad thing).
The configuration options, geometry, and items of the Listboxes are
not altered by tying them. The programmer will have to make sure that
the setup of the Listboxes make sense together. Here are some
(unenforced) guidelines:
For listboxes with tied selection:
set -exportselection to 0 for all but possibly one Listbox
use identical -selectmode for all Listboxes
if items are added/deleted, they should be done all at once and
at the same index, or the selection should be cleared
Listboxes should have the same number of items
For listboxes with tied scrolling:
use the same window height and font for all Listboxes
Listboxes should have the same number of items
- $listbox->tie?(?option?, [listbox,...])?
- Ties together $listbox and the list of Listboxes with the given
option. Returns $listbox.
If no arguments are given, returns a list containing two items: the
tie option ("scroll", "selection", or "all") and the list of Listboxes
that $listbox is tied to.
option can be one of "scroll", "selection", or "all". If omitted,
"all" is assumed. "scroll" makes the tied Listboxes to scroll
together, "selection" makes selections to occur simultaneously in all
tied Listboxes, and "all" effects both actions.
All the Listboxes are untied (if previously tied) before being tied
to each other; hence a Listbox can only be in one "tie group" at a
time. "Tiedness" is commutative.
The tie method can be called with either Listbox or TiedListbox
objects. All listbox objects specified are reblessed to TiedListbox
objects.
Code such as below can be used to tie ScrlListboxes:
$slb1=ScrlListbox(...); # or Scrolled('Listbox',...
$slb2=ScrlListbox(...); # or Scrolled('Listbox',...
$slb1->tie([$slb2->Subwidget('scrolled')]);
- $listbox->untie()
- This function unties the Listbox from its "tie group". The other items
in the "tie group" (if more than one) remain tied to each other.
Returns a list containing two items: the old tie option ("scroll",
"selection", or "all") and the list of Listboxes that $listbox was
tied to.
You probably don't care about these. They are just details to tie
together the behaviors of the listboxes.
All overriden methods take identical arguments as the corresponding
Listbox methods (see the Listbox documentation for a full
description). All overridden methods that take an index interpret that
index in the context of the listbox object provided.
- $listbox->activate(...) =item $listbox->selection(...)
- To allow tied selection, these functions are overridden for listboxes
tied together with the "selection" or "all" option. When an item is
selected or activated in one listbox, the items with the same index
(if present) are selected or activated in all tied listboxes.
The selection('includes',...) submethod returns only information
about the given $listbox.
- $listbox->scan(...) =item $listbox->see(...) =item $listbox->yview(...)
- To allow tied scrolling, these functions are overridden for listboxes
tied together with the "scroll" or "all" option. When one listbox is
scrolled, all the other tied listboxes are scrolled by the same number
of items (if possible). An attempt is made to keep items of the same
index at the top of each tied listbox, while not interfering with the
normal scrolling operations.
The yview method with no arguments returns only information about
the given $listbox.
Horizontal scrolling (via xview) is not tied.
Reblessing the widgets to TiedListbox might be too weird. It will
disable any additional features for widgets in a class derived from
Listbox (none yet that I know of).
The bindtags for reblessed widgets aren't updated. This is probably
wouldn't be a good thing to do automatically anyway.
Andrew Allen ada@fc.hp.com
This code may be distributed under the same conditions as Perl.