Extend player-based colour schemes (Fixes #14) and fix PNG generation issue (Fixes #37)

[Manik-Khajuria-5]

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Summary

This PR extends the colour scheme functionality in draw_tree and also fixes a PNG generation bug identified during testing.

It now:

• Resolves [Good first issue]: Add different options for colouring game graphics by player #14 by adding improved player-based colouring options.
• Fixes a PNG conversion issue (likely related to [Bug]: PNG generation always fails on local Mac #37) where the CLI attempted to convert a non-existent temporary PDF file instead of using the actual generated PDF path.

This contribution is submitted as part of my GSoC 2026 application (Project Idea 3: Layout algorithm for visualising game trees).

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Changes

Colour Scheme Improvements (Fixes #14)

• Improved existing "gambit" colour scheme:

  • Ensures proper scaling for multiple players.
  • Handles cases where the number of players exceeds predefined colours.

• Added new "distinctipy" colour scheme:

  • Uses the distinctipy package to dynamically generate visually distinct colours.
  • Suitable for games with many players.
  • Improves clarity in larger game trees.

• Updated get_player_color():

  • Added support for multiple schemes via color_scheme parameter.
  • Preserved backward compatibility (default behaviour unchanged).

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PNG Generation Fix (Related to #37)

• Fixed CLI PNG export logic.

• Previously, PNG conversion attempted to use a temporary PDF path that was never written.

• Updated logic to:

  • Use the actual PDF path returned by generate_pdf().
  • Ensure Ghostscript / ImageMagick operate on an existing file.

• Verified successful PNG generation locally.

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Dependencies

• distinctipy

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Testing

• Tested locally using sample .ef files.

• Verified correct TikZ output for:

  • Default scheme
  • "gambit" scheme
  • "distinctipy" scheme

• Verified:

  • PDF generation works
  • PNG generation works (after fix)
  • No regression in existing functionality

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Fixes #14

Default

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Gambit

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Distinctipy

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Fixes [#37]

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Closes #14

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Closes #37

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[edwardchalstrey1]

Hi @Manik-Khajuria-5 thanks for this. We will review this once we have received your project proposal. Thanks!

[Manik-Khajuria-5]

@edwardchalstrey1 I am currently working on project proposal will try to send it as soon as possible

[edwardchalstrey1]

@edwardchalstrey1 I am currently working on project proposal will try to send it as soon as possible

Thanks, but I believe there is a plenty of time (check the GSoC timeline), so no rush :)

[Manik-Khajuria-5]

@edwardchalstrey1 okk got it. Thanks

[edwardchalstrey1]

Thanks for this @Manik-Khajuria-5 but I'm now going to merge a different solution to the problem :)

[Manik-Khajuria-5]

@edwardchalstrey1 okk got it