[petercorke]

Summary

Adds graph(format="dot"|"mermaid"|"mermaid_fenced", filename=None, **kwargs)
alongside the existing dotfile()/showgraph() pair, following the same
pattern already established in MVTB's ImageBlobs.graph() and bdsim's
BlockDiagram.graph(): a single entry point returning rendered text
(optionally also written to a file), with GraphViz DOT staying as the
detailed/primary representation and Mermaid as a simplified alternative for
Markdown/Jupyter rendering.

• format="dot" wraps dotfile() (writes to an in-memory stream, returns
  the text) rather than duplicating its logic -- RTB's DOT output has real
  domain-specific richness (etsbox layout, jtype arrowheads, static
  coloring) that doesn't map onto Mermaid 1:1, so unlike MVTB's simpler
  blob-hierarchy case, dotfile() stays the source of truth for "dot"
  rather than being inverted into a thin wrapper around graph().
• format="mermaid"/"mermaid_fenced" is new: one node per link (double
  circle for end-effectors, hexagon for gripper links), edges labelled with
  joint type (R/P) and jindex for actuated joints.

Also fixes

• dotfile()'s open(filename, "w") had no encoding, the same bug PR
  use utf-8 #214 flagged in 2021 against the pre-src/-layout ERobot.py
  (dotfile() moved to BaseRobot.py since, bug survived the move).
  Fixes use utf-8 #214.
• draw_edge()'s static-joint edge styling concatenated
  edge_options += 'fontcolor="blue"' with no leading comma, producing
  invalid DOT (arrowhead="normal"fontcolor="blue") whenever static=True
  hit a non-joint link -- pre-existing, unrelated to this feature, just
  noticed while testing graph(format="dot") output.

Test plan

• New tests: test_graph_dot_matches_dotfile, test_graph_dot_kwargs_forwarded,
  test_graph_mermaid, test_graph_mermaid_fenced, test_graph_multiple_end_effectors,
  test_graph_writes_to_filename, test_graph_bad_format_raises
• Full local suite green

[codecov]

Codecov Report

❌ Patch coverage is 0% with 46 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (6994fad) to head (fca095c).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/roboticstoolbox/robot/BaseRobot.py	0.00%	46 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #586   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files        142     142           
  Lines      13788   13869   +81     
=====================================
- Misses     13788   13869   +81     

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