TreeWidget

1 Function

TreeWidget is a Python MegaWidget which displays a tree structure in a Tkinter text widget. Each tree node is displayed in one line, indented according to its depth. This gives a presentation similar to a hierarchical content table. The presentation of internal nodes can be folded (collapsed) or expanded. Folding removes the node's descendants from the display, expansion adds children or (optionally) descendants further down the line. Icons before the node representation show whether the node can be collapsed, expanded or is a leave.

The widget provides an update method to synchronize the display with a dynamically modified tree. It tries to keep a node's display state (expanded/collapsed) unchanged during updates (but may collapse expanded nodes for some forms of changes, e.g. reordering of children).

The widget tries hard to release internal resources early, allowing it to display dynamic trees associated with scarce resources.

TreeWidget uses Greg McFarlane's excellent Python MegaWidget Framework.

2 Usage Conditions

3 Alternatives

1. the TreeExplorer in Doug Hellmann's PmwContribD package
   It is easier to use than my TreeWidget and provides nicer symbols. It seems, however, not to support dynamically changing trees and early resource release.
2. the TreeWidget class in Guido's IDLE package
   In my TreeWidget module some things on Guido's todo list are done, especially partial and total redisplay (to support changing trees), keeping track of object ids, early release of functions implicitely defined for bindings. My TreeWidget is implemented as Pmw MegaWidget and uses a Pmw.ScrolledText as medium for tree display; Guido only requires plain Tkinter and uses a Canvas for tree display. His icon management is fancier. He supports more features in the basic infrastructure (double clicking opens/closes node, items are editable) that must be provided by the application in my framework (if they are needed).
3. Gene Cash's tree.py
   I did not yet look at it closely. The announcement, however, seems promissing: canvas based, speed independent of tree size, tries to narrowly emulate the Windows tree control (used e.g. by Windows explorer). Only nasty thing: GPL license (Martin Armstrong reported on 2002-08-12, that this is no longer true).

4 Requirements

TreeWidget requires Pmw and of cause Python to be installed. It has been tested with Pmw 0.8.0/0.8.1/0.8.3 and Python 1.5.2 but may run with other versions, too.

5 Download

6 Example

7 Versions

7.1 Version 0.05

• fixed: during update, nodes where created without parent

7.2 Version 0.04

• fixed: in some error cases, the tree became editable
• fixed: in some error cases, the children structure became inconsistent

7.3 Version 0.03

• improved icons
• arrow cursor

7.4 Version 0.02

• bug fixed: the tree was modifiable
• new option disableselection to disable the selection