rn-skia（斯基亚）

React Native Skia — Best Practices & Performance Guide

@shopify/react-native-skia 2.x / React Native >= 0.79 / React >= 19 / Reanimated v3+

Critical Rules

1. Never read .value in JSX render — pass shared values directly as props: <Circle cx={x} /> not <Circle cx={x.value} />.
2. Never create Skia objects in render — use useMemo for Paint, Path, PictureRecorder, RuntimeEffect.
3. Always mark worklet functions with "worklet" directive in useDerivedValue callbacks.
4. Animate properties, not structure — keep the component tree static; only animate numeric/color props.
5. Use Atlas for 10+ similar elements — single draw call beats N individual components.
6. Reuse Paint and PictureRecorder objects — creating per frame causes GC pressure and frame drops.
7. Prefer retained mode for UI animations (near-zero FFI cost); use immediate mode (Picture API) only for variable draw command counts (particles, generative art, games).
8. Use BlurMask over Blur for simple shapes — it's cheaper.
9. Order filters cheapest-first — MatrixColorFilter before Blur.
10. Load fonts/images at component level with useFont/useImage — handle null loading state before rendering.

Version Compatibility

Android API 26+ required for video support.

Installation

npm install @shopify/react-native-skia
# Postinstall downloads prebuilt Skia binaries — must run
# Bun: bun add --trust @shopify/react-native-skia
# pnpm v10+: add to pnpm.onlyBuiltDependencies in package.json

iOS: cd ios && pod install. Android ProGuard: add -keep class com.shopify.reactnative.skia.** {*;}.

Essential Imports

import {
  Canvas, Circle, Rect, RoundedRect, Line, Path, Group, Fill,
  Text, Paragraph, Image, ImageSVG,
  LinearGradient, RadialGradient, SweepGradient,
  Blur, BlurMask, Shadow, BackdropBlur, MatrixColorFilter,
  RuntimeShader, FractalNoise, Turbulence, ImageShader,
  Atlas, Picture, Vertices, Patch, DiffRect, FitBox, Box,
  useFont, useImage, useSVG, useCanvasRef,
  Skia, vec, rect, rrect, drawAsImage,
  usePathInterpolation, useRSXformBuffer, useRectBuffer, useClock,
  interpolateColors,
} from "@shopify/react-native-skia";

import {
  useSharedValue, useDerivedValue, withTiming, withSpring,
  withRepeat, withSequence, withDelay, withDecay, cancelAnimation,
} from "react-native-reanimated";

Core Pattern — Retained Mode Animation

const x = useSharedValue(0);
const scale = useSharedValue(1);

useEffect(() => {
  x.value = withSpring(200);
  scale.value = withSpring(1.5);
}, []);

return (
  <Canvas style={{ flex: 1 }}>
    <Group transform={[{ translateX: x }, { scale }]}>
      <Circle cx={0} cy={100} r={50} color="cyan" />
    </Group>
  </Canvas>
);

Rendering Mode Selection

Performance Quick Reference

Fastest (use freely):      Circle, Rect, Line, Group transforms, MatrixColorFilter
Fast (use moderately):     Path (simple), BlurMask, LinearGradient
Slow (use sparingly):      BackdropBlur, RuntimeShader, DisplacementMap, Blur (large radius)

Targets: 60fps = 16.67ms budget, 120fps = 8.33ms budget. Memory < 100MB. JS thread < 50%.

Anti-Patterns to Fix on Sight

Code Review Action

When asked to review/audit/check Skia code:

1. Scan all files importing @shopify/react-native-skia.
2. Check against Critical Rules and Anti-Patterns table.
3. Report in table: | File | Line | Issue | Severity | Fix |
4. Severity: CRITICAL (crash/broken render), HIGH (frame drops), MEDIUM (sub-optimal), LOW (style).
5. Fix all issues if confirmed, then re-scan to verify zero violations.

Reference Files

Read these as needed for detailed API docs, examples, and patterns:

• Getting Started: Installation (npm/yarn/Expo/Bun/pnpm), platform setup (iOS/Android/Web), postinstall scripts, Hello World, Canvas component, Skia object API, project structure, troubleshooting build errors, bundle size.
• Canvas & Rendering Modes: Retained mode (declarative components, display list, near-zero FFI), immediate mode (Picture API, PictureRecorder, direct draw commands), combining both modes, offscreen/headless rendering, canvas snapshots, custom renderers, platform considerations.
• Shapes & Drawing: All shape components (Circle, Rect, RoundedRect, Oval, Line, Points, Fill, Path with SVG notation, Atlas/RSXform sprite batching, Vertices, Patch, DiffRect), Group transforms/blend modes/clipping, Paint component, FitBox, Box with shadow, path trimming animation.
• Animations: Reanimated v3 integration (shared values as direct props), animation types (timing/spring/decay/repeat/sequence), derived values, Skia hooks (usePathInterpolation, usePathValue, useClock, useRectBuffer, useRSXformBuffer), color animations (interpolateColors), gesture integration (pan/pinch/rotation/multi-touch), complete examples (pulsing button, spinner, bouncing ball).
• Shaders & Gradients: Linear/Radial/Sweep/TwoPointConical gradients, animated gradients, FractalNoise/Turbulence, custom SkSL runtime shaders (wave distortion, chromatic aberration, glow, aurora, water ripple), ShaderLib functions, ImageShader texturing, shader composition, performance (half precision, cache programs).
• Filters & Effects: Image filters (Blur, Offset, Morphology, DisplacementMap, Shadow, RuntimeShader), mask filters (BlurMask styles: normal/solid/outer/inner), color filters (MatrixColorFilter with grayscale/sepia/invert/brightness/contrast matrices, BlendColor, LumaColorFilter, Lerp), path effects (Discrete, Dash, Corner, Path1D, Path2D, Line2D, Sum), BackdropBlur/BackdropFilter, Mask (alpha/luminance), frosted glass/neon glow/vintage photo examples.
• Text & Fonts: Text component (baseline positioning), useFont hook, system fonts, matchFont, Paragraph builder (rich text, styles, alignment), TextPath (text along curves), TextBlob, Glyphs, font metrics/measurement, animated text (position, font size), marquee/typewriter/shadow examples.
• Images & Media: useImage hook (require/URL/bundle), Image component (fit modes, sampling), programmatic image creation (base64, raw pixels, drawAsImage), image manipulation (resize, encode, read pixels), AnimatedImage (GIF/WebP), SVG (useSVG, ImageSVG, from string), Video playback (useVideo, controls), Skottie/Lottie (animation, dynamic properties, slots), canvas snapshots, image effects.
• Performance Optimization: Rendering pipeline (JS→UI→GPU), 60fps/120fps frame budgets, retained vs immediate mode characteristics, animation performance (shared values, derived values, batching, worklets), component structure optimization (flat trees, Groups, static Pictures), memory management (reuse objects, dispose images, resize), Atlas for high-perf rendering, filter cost hierarchy, platform-specific tips (iOS Metal, Android OpenGL/androidWarmup, Web CanvasKit), profiling (useFrameCallback FPS counter, React DevTools, native profilers), common pitfalls checklist.
• Advanced Patterns: Architecture (component composition, DrawingContext, atomic/molecular components, custom hooks, render props), real-world examples (interactive bar chart, particle system with Atlas, drawing canvas with gestures, progress ring, waveform visualizer), design system integration (theme provider with Skia colors), testing (unit tests, visual regression), debugging (visual grid overlay, performance monitor), common patterns (skeleton loading, ripple effect, confetti).