custom-canvas-and-gestures
Enforces CustomPainter/Canvas discipline — the View/Painter/Scene split with a dumb painter fed one immutable Scene value type, shouldRepaint as a single value compare kept strictly separate from the AnimationController-as-repaint animation path, one shared affine transform read by BOTH painter and hit-tester (toCanvas/toLogical exact inverses, never re-derive scale), geometry hit-testing (integer lattice or rasterized region-ID buffer, never Path.contains), zero-allocation paint(), gesture-as-pure-translator emitting a typed command to a Notifier (never mutating in the handler), ExcludeSemantics + sibling Semantics speaking display values with redundant non-colour encoding, measured TextPainter fitting, first-party RoundedSuperellipseBorder, physical-pixel hairlines, and Directional-only geometry. Use when writing or reviewing a CustomPainter/CustomPaint, gestures on a canvas, tap/drag hit-testing, canvas animation, measured text fitting, or Semantics over custom-drawn pixels.
Install
With your agent
Install OMGSkills skill "zakariaf/flutter-skills:skills/custom-canvas-and-gestures" into this agent's normal skills directory: call the OMGSkills MCP get_install_plan tool for your agent and run the script it returns (it installs only the pinned commit and verifies SKILL.md), and stop if MCP or the pin is unavailable. Do not overwrite or change existing skills without asking me.
Manual command
git clone https://github.com/zakariaf/Flutter-Skills /tmp/Flutter-Skills && ln -s /tmp/Flutter-Skills/skills/custom-canvas-and-gestures ~/.claude/skills/custom-canvas-and-gesturesFrom README
Custom Canvas & Gestures Hand-painted surfaces (CustomPainter/Canvas) own every pixel, so they look byte-identical across platforms — but only if the painter stays dumb, the coordinate math is shared, and gestures translate rather than decide. This skill is the contract for that layer: how it splits, how pixels and pointers agree, and how a screen reader hears a canvas. Read the reference for the task at hand: references/painter-and-scene.md — the View/Painter/Scene split, the shared transform, hit-testing by geometry class, zero-allocation paint(), the two-path repaint pitfall. references/gestures-and-semantics.md — gesture-as-translator, arena arbitration, clamp-not-collision drags, custom-canvas Semantics, action/gesture parity. references/text-and-shapes.md — measured TextPainter fitting, optical centring, RoundedSuperellipseBorder, physical-pixel hairlines, concentric radii, painter-over-image-asset. Run scripts/checkpainterhygiene.sh and scripts/analyze.sh before a PR.
More from this repo
accessibility-as-code
Enforces accessibility as a correctness property authored into each widget — Semantics(button/label) or...
adaptive-layout
Enforces adapting layout by available CONSTRAINTS/size, never device or platform checks — LayoutBuilder +...
ads-and-iap-monetization
Enforces opt-in, rewarded-first monetization over the service seam — a rewarded view grants exactly one benefit and...