qtPyGraphEdit

A graphical node-edge graph editor, in Python and Qt (PySide6). Currently very much in development, in a pre-alpha state.

V0.0.0
V0.1.0

The interface - an (editable) object list on the left, and the editable graph on the right. Tools on the top.

The black circle adds Nodes (shortcut - "N"), the tracks add Edges ("E") The pointer goes into select mode. Double click the text in the list to edit names. Selection in one window shows in the other. I think the menu options are self explanatory?

This is a prototype and learning project. My primary goal is to learn Qt/ Pyside, and to figure out the patterns needed to support model (repository) -based, multi-graphical view higraphs. I have some blog posts about the project here

Given that there seem to be very few (no?) graphical graph editors in Python, it is possible that someone may see the utility in taking this rolling chassis, and turning it into a graphical front-end for something like networkx. Since this has a (rudimentary) live Python scripting window, it can be extended to support command line and GUI interactions.

V0 is a simple node-edge graph editor

Goal: Build a basic PySide6 framework for a model-viewController, with a truly independent Graph model This is currently based on a simple custom Graph library, which will be extended to higraphs in V1. One could use networkx or an equivalent at this point, but it doesn't support higraphs, so the work will have to be done sooner or later.

V0.0

• Dictionary of nodes and edges with meta data.
• Displayed in a text list and graphically
• Edit the graph - add, delete, edit text for nodes & edges, move nodes, reroute edges.
• Save and load (Graphml with yED extensions). This uses code from yEdExtended
• Copy/ Paste as text, graphics and internally to duplicate items.
• A rudimentary Python shell that runs with (write!) access to the Graph, Scene and Model data.
• NOTE: This version uses the qtcreator .ui files, which places some constraints on what one can do. There are some workarounds to this in the code. As I understand Qt better, hopefully there will be fewer of these!

Currently, V00 has a bug on deleting an edge, such that quite often, but not always, the edge is removed from the data structures, but the Qt Scene still draws it.

V0.1

There has been quite a lot of refactoring of the code. the yEd library, which was an invaluable stepping stone for persistence in V00 has been replaced with internal XML read/ write code. As I begin to understand Qt better, I fix things. There are still ~70 TODOs, but a number have been dealt with, and many are reminders for future versions.

• Hermite splines for edges - based around this code. I really think Bezier splines are an ugly way to edit curves.
• Multipoint edges - all edges can have multiple bend points.
• Edges are editable, and can be directed or undirected, and rectilinear or spline. Only one sort of arrow-head at this point!
• Text display and edit for extended metadata (was in V0.3, but got moved here)
• Models still round-trip to yEd, but metadata currently does not pull through, and the Hermite spline points become Bezier control points, so the curves look different.

The editing dialog. It is simple and functional - I'm still working out how to use Qt!

TODO:

V0.2

I have revised my road map. I looked at the work to implement hyperedges, and decided that I will get more motivation from having nodes-as-sets, or blobs, as Harel calls them. So hyperedges have moved out to the next iteration. Refactoring is hard!

• Higraphs - nodes become sets. This will likely be strictly heirarchical sets (ie no set intersections/ overlaps)

V0.3

Hyperedges - n-ended edges.

V0.4

• Multiple tabs - editable views of different subsets of the master Graph model

V0.5

• Overlapping sets.

Getting Started with editing the code

If you are totally new to Qt (or PySide, the Python version used here), this is a good tutorial

Otherwise,

• create a folder,
• create a virtual enviroment python -m venv C:\path\to\new\virtual\environment (and make it active with scripts\activate)
• install PySide with pip install PySide6
• copy all the code from here (git clone https://github.com/ghillebrand/qtPyGraphEdit.git) or download the zip from the green Code button above.
• Run python mainwindow.py, or open mainwindow.py with you favourite editor. I use VSCodium: VSCode without the telemetry back to Microsoft.
• If you want to edit the dialogs, then you need the Qt designer qtcreator and to compile the .ui files to .py. The command is pyside6-uic <file>.ui -o <file>.py

The code comes with no guarantees at this point - not even that it will run! It certainly has rough edges and bugs. I do try to check that what's here runs, but this is still very much the beginning of a much longer journey.