Hacktoberfest 2026: the issues maintainers tagged for October, open and beginner-friendly. Browse Hacktoberfest issues

NullReferenceException in >GraphViewer.CreateRectToFillCanvas() when re-assigning the graph

Open
  • Is something wrong?
#310 1 comment 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
30/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
csharp
Domain
desktop

Research direction

Start with AutomaticGraphLayoutControl.SetGraph() and follow the re-assignment path into GraphViewer.CreateRectToFillCanvas(). Reproduce assigning a graph, assigning null, and assigning the same graph again; done means the sequence no longer throws a NullReferenceException.

Written by the indexing model from the issue text.

Description

hi, when using the AutomaticGraphLayoutControl, assigning a graph, then assigning null and then assigning the same graph (I didn't test with a different graph...), a NRE is thrown because the Parent of the GraphCanvas was null.

this is fixed by changing the way AutomaticGraphLayoutControl.SetGraph() handles the re-assignment case... just some if statements need to be changed.
i have a fix in my fork. should i PR it?

Dominant language
C#
Stars
1.5k
Forks
319
No merged PRs in 30d

Getting set up

We have not checked this project's setup files yet. Start from its README, and see our first-contribution guide for the general steps.

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from microsoft/automatic-graph-layout

All issues in microsoft/automatic-graph-layout

Similar issues

More C# issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.