
=head1 NAME

Tk::Tree - Create and manipulate Tree widgets

=for pm Tixish/Tree.pm

=for category Tix Extensions

=head1 SYNOPSIS

S<    >B<use Tk::Tree;>

S<    >I<$tree> = I<$parent>-E<gt>B<Tree>(?I<options>?);

=head1 SUPER-CLASS

The B<Tree> class is derived from the L<HList|Tk::HList> class and inherits all
the methods, options and subwidgets of its super-class.  A B<Tree> widget is
not scrolled by default.

=head1 STANDARD OPTIONS

B<Tree> supports all the standard options of an HList widget.
See L<Tk::options> for details on the standard options.

=head1 WIDGET-SPECIFIC OPTIONS

=over 4

=item Name:		B<browseCmd>

=item Class:		B<BrowseCmd>

=item Switch:		B<-browsecmd>

Specifies a L<callback|Tk::callbacks> to call whenever the user browses on an entry
(usually by single-clicking on the entry). The callback is called with
one argument, the pathname of the entry.

=item Name:		B<closeCmd>

=item Class:		B<CloseCmd>

=item Switch:		B<-closecmd>

Specifies a L<callback|Tk::callbacks> to call whenever an entry needs to be closed (See
L<"BINDINGS"> below). This method is called with one argument,
the pathname of the entry. This method should perform appropriate
actions to close the specified entry. If the B<-closecmd> option
is not specified, the default closing action is to hide all child
entries of the specified entry.

=item Name:		B<command>

=item Class:		B<Command>

=item Switch:		B<-command>

Specifies a L<callback|Tk::callbacks> to call whenever the user activates an entry
(usually by double-clicking on the entry). The callback
is called with one argument, the pathname of the entry.

=item Name:		B<ignoreInvoke>

=item Class:		B<IgnoreInvoke>

=item Switch:		B<-ignoreinvoke>

A Boolean value that specifies when a branch should be opened or
closed. A branch will always be opened or closed when the user presses
the (+) and (-) indicators. However, when the user invokes a branch
(by doublc-clicking or pressing E<lt>ReturnE<gt>), the branch will be opened
or closed only if B<-ignoreinvoke> is set to false (the default
setting).

=item Name:		B<openCmd>

=item Class:		B<OpenCmd>

=item Switch:		B<-opencmd>

Specifies a L<callback|Tk::callbacks> to call whenever an entry needs to be opened (See
L<"BINDINGS"> below). This method is called with one argument,
the pathname of the entry. This method should perform appropriate
actions to open the specified entry. If the B<-opencmd> option
is not specified, the default opening action is to show all the child
entries of the specified entry.

=back

=head1 DESCRIPTION

The B<Tree> method creates a new window and makes it into a Tree widget
and return a reference to it.  Additional options, described above, may
be specified on the command line or in the option database to configure
aspects of the Tree widget such as its cursor and relief.

The Tree widget can be used to display hierarchical data in a tree
form. The user can adjust the view of the tree by opening or closing
parts of the tree.

To display a static tree structure, you can add the entries into the
Tree widget and hide any entries as desired. Then you can call
the B<autosetmode> method. This will set up the Tree widget so that it
handles all the I<open> and I<close> events automatically.
the demonstration program F<Tixish/examples/perl-tix-tree>).

The above method is not applicable if you want to maintain a dynamic tree
structure, i.e, you do not know all the entries in the tree and you need
to add or delete entries subsequently. To do this, you should first create
the entries in the Tree widget. Then, use the B<setmode> method to
indicate the entries that can be opened or closed, and use the B<-opencmd>
and B<-closecmd> options to handle the opening and closing events. (Please
see the demonstration program F<Tixish/examples/perl-tix-dyntree>).

Use either

S<    >I<$parent>-E<gt>B<Scrolled>(B<'Tree'>, ... );

or

S<    >I<$parent>-E<gt>B<ScrlTree>( ... );

to create a scrolled B<Tree>. See L<Tk::Scrolled> for details.

=head1 WIDGET METHODS

The B<Tree> method creates a widget object.
This object supports the B<configure> and B<cget> methods
described in L<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
L<Tk::Widget|Tk::Widget> class.

The following additional methods are available for Tree widgets:

=over 4

=item I<$tree>-E<gt>B<autosetmode>

This method calls the B<setmode> method for all the entries in
this Tree widget: if an entry has no child entries, its mode is set to
B<none>. Otherwise, if the entry has any hidden child entries, its
mode is set to B<open>; otherwise its mode is set to B<close>.

=item I<$tree>-E<gt>B<close>(I<entryPath>)

Close the entry given by I<entryPath> if its I<mode> is B<close>.

=item I<$tree>-E<gt>B<getmode>(I<entryPath>)

Returns the current I<mode> of the entry given by I<entryPath>.

=item I<$tree>-E<gt>B<open>(I<entryPath>)

Open the entry given by I<entryPath> if its I<mode> is B<open>.

=item I<$tree>-E<gt>B<setmode>(I<entryPath, mode>)

This method is used to indicate whether the entry given by
I<entryPath> has children entries and whether the children are
visible. I<mode> must be one of B<open>,
B<close> or B<none>. If I<mode> is set to B<open>, a (+)
indicator is drawn next the the entry. If I<mode> is set to
B<close>, a (-) indicator is drawn next the the entry. If
I<mode> is set to B<none>, no indicators will be drawn for this
entry. The default I<mode> is none. The B<open> mode indicates
the entry has hidden children and this entry can be opened by the
user. The B<close> mode indicates that all the children of the entry
are now visible and the entry can be closed by the user.

=back

=head1 BINDINGS

The basic mouse and keyboard bindings of the Tree widget are the same
as the L<bindings of the HList|Tk::HList/"BINDINGS"> widget.
In addition, the entries can be opened or closed under the following
conditions:

=over 4

=item [1]

If the I<mode> of the entry is B<open>, it can be opened by clicking
on its (+) indicator.

=item [2]

If the I<mode> of the entry is B<close>, it can be closed by clicking
on its (-) indicator.

=back

=head1 SEE ALSO

L<Tk::HList|Tk::HList>

=head1 AUTHOR

Perl/TK version by Chris Dean <ctdean@cogit.com>.  Original Tcl/Tix
version by Ioi Kim Lam.

=head1 ACKNOWLEDGEMENTS

Thanks to Achim Bohnet <ach@mpe.mpg.de> for all his help.

=cut

