react-native-animations

name	react-native-animations
description	Master animations - Reanimated 3, Gesture Handler, layout animations, and performance optimization
sasmp_version	1.3.0
bonded_agent	05-react-native-animation
bond_type	PRIMARY_BOND
version	2.0.0
updated	2025-01

React Native Animations Skill

Learn high-performance animations using Reanimated 3, Gesture Handler, and layout animations.

Prerequisites

• React Native basics
• Understanding of JavaScript closures
• Familiarity with transforms and styles

Learning Objectives

After completing this skill, you will be able to:

• Create smooth 60fps animations with Reanimated
• Handle complex gestures with Gesture Handler
• Implement layout entering/exiting animations
• Optimize animations for performance
• Combine gestures with animations

---

Topics Covered

1. Installation

npm install react-native-reanimated react-native-gesture-handler

# babel.config.js
module.exports = {
  plugins: ['react-native-reanimated/plugin'],
};

2. Reanimated Basics

import Animated, {
  useSharedValue,
  useAnimatedStyle,
  withSpring,
} from 'react-native-reanimated';

function AnimatedBox() {
  const scale = useSharedValue(1);

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

  const handlePress = () => {
    scale.value = withSpring(scale.value === 1 ? 1.5 : 1);
  };

  return (
    <Pressable onPress={handlePress}>
      <Animated.View style={[styles.box, animatedStyle]} />
    </Pressable>
  );
}

3. Gesture Handler

import { Gesture, GestureDetector } from 'react-native-gesture-handler';

function DraggableBox() {
  const translateX = useSharedValue(0);
  const translateY = useSharedValue(0);

  const pan = Gesture.Pan()
    .onUpdate((e) => {
      translateX.value = e.translationX;
      translateY.value = e.translationY;
    })
    .onEnd(() => {
      translateX.value = withSpring(0);
      translateY.value = withSpring(0);
    });

  const style = useAnimatedStyle(() => ({
    transform: [
      { translateX: translateX.value },
      { translateY: translateY.value },
    ],
  }));

  return (
    <GestureDetector gesture={pan}>
      <Animated.View style={[styles.box, style]} />
    </GestureDetector>
  );
}

4. Layout Animations

import Animated, { FadeIn, FadeOut, Layout } from 'react-native-reanimated';

function AnimatedList({ items }) {
  return (
    <Animated.View layout={Layout.springify()}>
      {items.map((item) => (
        <Animated.View
          key={item.id}
          entering={FadeIn}
          exiting={FadeOut}
          layout={Layout.springify()}
        >
          <Text>{item.title}</Text>
        </Animated.View>
      ))}
    </Animated.View>
  );
}

5. Animation Timing

Function	Use Case
withTiming	Linear, controlled duration
withSpring	Natural, physics-based
withDecay	Momentum-based (fling)
withSequence	Multiple animations in order
withRepeat	Looping animations

---

Quick Start Example

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

function SwipeCard() {
  const translateX = useSharedValue(0);

  const gesture = Gesture.Pan()
    .onUpdate((e) => { translateX.value = e.translationX; })
    .onEnd(() => { translateX.value = withSpring(0); });

  const style = useAnimatedStyle(() => ({
    transform: [
      { translateX: translateX.value },
      { rotate: `${interpolate(translateX.value, [-200, 200], [-15, 15])}deg` },
    ],
  }));

  return (
    <GestureDetector gesture={gesture}>
      <Animated.View style={[styles.card, style]} />
    </GestureDetector>
  );
}

---

Common Errors & Solutions

Error	Cause	Solution
"Attempted to call from worklet"	Missing runOnJS	Wrap with runOnJS()
Animation not running	Missing 'worklet'	Add 'worklet' directive
Gesture not working	Missing root view	Add GestureHandlerRootView

---

Validation Checklist

• Animations run at 60fps
• Gestures respond smoothly
• No frame drops on low-end devices
• Layout animations don't cause jank

---

Usage

Skill("react-native-animations")

Bonded Agent: 05-react-native-animation