Add output_dpi option (port of upstream PR #379)

[SomethingNew71]

Summary

Ports upstream PR #379 — exposes Graphviz's dpi graph attribute as a top-level WireViz YAML option, letting users render higher-resolution PNGs without changing CLI invocations.

Usage

options:
  output_dpi: 192   # 2x default → 4x pixel area in the PNG

connectors:
  ...

Default is 96.0, matching Graphviz's own default for non-PostScript renderers, so existing harnesses render at the exact same pixel dimensions they always have.

What changed

File	Change
DataClasses.py	New Options.output_dpi: Optional[float] = 96.0 field
Harness.py	Passes dpi=str(self.options.output_dpi) into the Graphviz graph attrs in create_graph()
docs/syntax.md	Documents the new option
examples/*.gv, tutorial/*.gv (23 files)	Rebaselined — every .gv now carries dpi=96.0

Why the .gv rebaseline ships with this PR

Every .gv gets a single new line (dpi=96.0) on the graph attr. Without committing the rebaselined .gv files, every future build_examples.py compare run would show 23 files changed on first rebuild and force contributors to mentally filter out "oh that's just the dpi attribute." The PNG/SVG/HTML outputs are environment-dependent (graphviz version) and intentionally left as the original baseline, per the project's "owner will rebuild" convention. ex08.gv is also intentionally left at baseline because it still contains absolute image paths from the original maintainer's machine that would be worse to overwrite.

Verification

• Default DPI: a demo harness PNG renders at 428×195 — matches pre-PR baseline.
• output_dpi: 192: the same harness renders at 857×391 — exactly 2× linear scale, 4× pixel area, as expected.
• build_examples.py runs cleanly across all 14 examples + 8 tutorials + 2 demos.

Differences from upstream PR wireviz#379

• Trivial port — the upstream patch applied cleanly with only stylistic tweaks (consistent string quoting, removed extra spaces around =).
• Added an explanatory comment on the Options.output_dpi field linking to the Graphviz docs.

Test plan

• CI workflow passes
• output_dpi: 192 produces 2× resolution PNG vs default
• No visual regressions at default DPI

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces a new output_dpi configuration option to WireViz, enabling control over Graphviz output resolution and size units. The changes span documentation, data structures, and graph generation logic, with updates to all example and tutorial files. A review comment identifies a potential issue where null values could be incorrectly passed as the string "None" to Graphviz and suggests passing the raw value instead.

[gemini-code-assist]

Using str(self.options.output_dpi) will result in the literal string "None" being passed to Graphviz if output_dpi is explicitly set to null in the YAML configuration, which is likely invalid. Since the graphviz library handles None by omitting the attribute and automatically converts numeric types to strings, passing the value directly is more robust and allows users to opt-out of an explicit DPI setting if desired.

Suggested change

	dpi=str(self.options.output_dpi),
	dpi=self.options.output_dpi,

[SomethingNew71]

@tobiasfalk — heads up, your upstream #379 (output_dpi option) is being incorporated here.

Context: We use WireViz to document Classic Mini Cooper wiring harnesses at Classic Mini DIY and are building a GUI on top of it. Upstream wireviz/WireViz looks abandoned (no real master commits since v0.4.1 in 2021, the dev refactor has been sitting unreleased for over a year), so we're forking and pulling in the open PRs we want.

This one was a near-faithful port — only stylistic tweaks (consistent string quoting, an explanatory comment linking to the Graphviz dpi docs). The default of 96.0 keeps existing harnesses rendering at identical pixel dimensions; verified that output_dpi: 192 produces exactly 2× linear scale in the PNG.

Commit attribution links back to your PR. Thanks for the work.