Tk::Tree - Create and manipulate Tree widgets

use Tk::Tree;

$tree = $parent->Tree(?options?);

The Tree class is derived from the HList class and inherits all the methods, options and subwidgets of its super-class. A Tree widget is not scrolled by default.

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

Name: browseCmd

Class: BrowseCmd

Switch: -browsecmd

Specifies a callback 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.

Name: closeCmd

Class: CloseCmd

Switch: -closecmd

Specifies a callback to call whenever an entry needs to be closed (See 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 -closecmd option is not specified, the default closing action is to hide all child entries of the specified entry.

Name: command

Class: Command

Switch: -command

Specifies a callback 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.

Name: ignoreInvoke

Class: IgnoreInvoke

Switch: -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 <Return>), the branch will be opened or closed only if -ignoreinvoke is set to false (the default setting).

Name: openCmd

Class: OpenCmd

Switch: -opencmd

Specifies a callback to call whenever an entry needs to be opened (See 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 -opencmd option is not specified, the default opening action is to show all the child entries of the specified entry.

The 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 autosetmode method. This will set up the Tree widget so that it handles all the open and close events automatically. the demonstration program 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 setmode method to indicate the entries that can be opened or closed, and use the -opencmd and -closecmd options to handle the opening and closing events. (Please see the demonstration program Tixish/examples/perl-tix-dyntree).

Use either

$parent->Scrolled('Tree', ... );

or

$parent->ScrlTree( ... );

to create a scrolled Tree. See Tk::Scrolled for details.

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

The following additional methods are available for Tree widgets:

$tree->autosetmode

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

$tree->close(entryPath)

Close the entry given by entryPath if its mode is close.

$tree->getmode(entryPath)

Returns the current mode of the entry given by entryPath.

$tree->open(entryPath)

Open the entry given by entryPath if its mode is open.

$tree->setmode(entryPath, mode)

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

The basic mouse and keyboard bindings of the Tree widget are the same as the bindings of the HList widget. In addition, the entries can be opened or closed under the following conditions:

[1]

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

[2]

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

Tk::HList

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

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