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Complete React Native and Expo optimization guide combining Callstack profiling with Vercel code patterns. Covers FPS, TTI, bundle size, memory, lists, animations, state, UI, and React Compiler. Use for any React Native performance, debugging, or best practices task.

Use this Skill: https://skilld.dev/gh/gigs-slc/react-native-skills/react-native

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rulesanimation-gesture-detector-press.md

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Use GestureDetector for Animated Press States

For animated press states (scale, opacity on press), use GestureDetector with Gesture.Tap() and shared values instead of Pressable's onPressIn/onPressOut. Gesture callbacks run on the UI thread as worklets—no JS thread round-trip for press animations.

Incorrect (Pressable with JS thread callbacks):

import { Pressable } from 'react-native'
import Animated, {
  useSharedValue,
  useAnimatedStyle,
  withTiming,
} from 'react-native-reanimated'

function AnimatedButton({ onPress }: { onPress: () => void }) {
  const scale = useSharedValue(1)

  const animatedStyle = useAnimatedStyle(() => ({
    transform: [{ scale: scale.value }],
  }))

  return (
    <Pressable
      onPress={onPress}
      onPressIn={() => (scale.value = withTiming(0.95))}
      onPressOut={() => (scale.value = withTiming(1))}
    >
      <Animated.View style={animatedStyle}>
        <Text>Press me</Text>
      </Animated.View>
    </Pressable>
  )
}

Correct (GestureDetector with UI thread worklets):

import { Gesture, GestureDetector } from 'react-native-gesture-handler'
import Animated, {
  useSharedValue,
  useAnimatedStyle,
  withTiming,
  interpolate,
  runOnJS,
} from 'react-native-reanimated'

function AnimatedButton({ onPress }: { onPress: () => void }) {
  // Store the press STATE (0 = not pressed, 1 = pressed)
  const pressed = useSharedValue(0)

  const tap = Gesture.Tap()
    .onBegin(() => {
      pressed.set(withTiming(1))
    })
    .onFinalize(() => {
      pressed.set(withTiming(0))
    })
    .onEnd(() => {
      runOnJS(onPress)()
    })

  // Derive visual values from the state
  const animatedStyle = useAnimatedStyle(() => ({
    transform: [
      { scale: interpolate(withTiming(pressed.get()), [0, 1], [1, 0.95]) },
    ],
  }))

  return (
    <GestureDetector gesture={tap}>
      <Animated.View style={animatedStyle}>
        <Text>Press me</Text>
      </Animated.View>
    </GestureDetector>
  )
}

Store the press state (0 or 1), then derive the scale via interpolate. This keeps the shared value as ground truth. Use runOnJS to call JS functions from worklets. Use .set() and .get() for React Compiler compatibility.

Reference: Gesture Handler Tap Gesture

Source: SKILL.md on GitHub

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Signed by skilld at 1d299ca. This ties the file your Agent reads to that commit on GitHub. It does not review the instructions.

Last checked against GitHub 2 days ago.

Dormantupdated 8 months ago
Other metadata
metadata
{
  "author": "Callstack + Vercel",
  "version": "1.0.0",
  "tags": "react-native, expo, performance, optimization, patterns"
}

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