added the download image button

[blueprintparadise]

Added an option to download the graph as a png.

[blueprintparadise]

Hey @punnerud , any update on this ?

[punnerud]

@blueprintparadise Thanks for this, and sorry for the wait. The feature is wanted and it is included in #4 — with the export moved to the client side, and you credited via Co-authored-by.

The reason for changing the implementation rather than merging as-is: the server-side version re-plots the graph with networkx.spring_layout, which lays the nodes out from scratch. So the button says "Download PNG" but hands back a different picture than the one on screen — different positions, no node sizing, no edge weights. Since vis.js already renders to a <canvas>, canvas.toBlob() gives exactly what the user is looking at, with no new dependency.

Three other things that would have bitten in production:

• latest_graph_data is a module-level global, so two people querying at once overwrite each other's graph and can download someone else's result.
• matplotlib.pyplot inside a Flask request thread needs matplotlib.use("Agg") first; without it the default backend can try to touch the GUI and crash, which on macOS is a hard failure.
• e["value"] raises KeyError on any edge without that key.

Also, the imported FileSaver.js is never used, and dropping stream_with_context from the imports is fine only because it was already unused.

If you would rather have the server-side route as well — for scripting or automation, where there is no canvas to read — that is a reasonable thing to want and I would take a follow-up PR for a /export/image that takes the graph in the request body instead of reading a global, with the Agg backend set explicitly.

Superseded by #4, but the feature is yours — leaving this open for @punnerud to decide.

[punnerud]

@blueprintparadise Your feature is shipped and released — it is in mpe-lkg 0.3.0, and you are credited with Co-authored-by on the commit.

Closing this one because it can no longer be merged: the conflicts GitHub is showing are in exactly the three files that moved or went away when the project became a pip package — app.py is now src/mpe_lkg/app.py, templates/index.html is now src/mpe_lkg/templates/index.html, and requirements.txt was replaced by pyproject.toml. Resolving them would mean reinstating the server-side rendering that was deliberately swapped out, so there is nothing here left to merge.

For the record, the reason for the swap rather than a straight merge: networkx.spring_layout lays the nodes out from scratch, so the button said "Download PNG" but handed back a different picture than the one on screen — different positions, no node sizing, no edge weights. vis.js already renders to a <canvas>, so canvas.toBlob() gives exactly what the user is looking at, with no new dependency. The global latest_graph_data, matplotlib.pyplot in a Flask thread without the Agg backend, and the KeyError on e["value"] were the other three reasons.

If you still want a server-side route for scripting — where there is no canvas to read — that is a reasonable thing to want and I would take a fresh PR for a /export/image that takes the graph in the request body instead of reading a global, with Agg set explicitly. Thanks for the contribution, and sorry it sat for so long.