feat: scroll behavior with pan gesture

06-scroll-behavior-with-pan-gesture/.expo-shared/assets.json

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+{
+  "12bb71342c6255bbf50437ec8f4441c083f47cdb74bd89160c15e4f43e52a1cb": true,
+  "40b842e832070c58deac6aa9e08fa459302ee3f9da492c7e77d93d2fbf4a56fd": true
+}

06-scroll-behavior-with-pan-gesture/.gitignore

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+node_modules/
+.expo/
+npm-debug.*
+*.jks
+*.p8
+*.p12
+*.key
+*.mobileprovision
+*.orig.*
+web-build/
+
+# macOS
+.DS_Store

06-scroll-behavior-with-pan-gesture/App.tsx

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+import { StatusBar } from 'expo-status-bar';
+import React from 'react';
+import { StyleSheet, Text, View } from 'react-native';
+import {
+  PanGestureHandler,
+  PanGestureHandlerGestureEvent,
+} from 'react-native-gesture-handler';
+import Animated, {
+  cancelAnimation,
+  useAnimatedGestureHandler,
+  useDerivedValue,
+  useSharedValue,
+  withDecay,
+} from 'react-native-reanimated';
+import Page, { PAGE_WIDTH } from './components/Page';
+
+const titles = ["What's", 'up', 'mobile', 'devs?'];
+
+type ContextType = {
+  x: number;
+};
+
+const MAX_TRANSLATE_X = -PAGE_WIDTH * (titles.length - 1);
+
+export default function App() {
+  const translateX = useSharedValue(0);
+
+  const clampedTranslateX = useDerivedValue(() => {
+    return Math.max(Math.min(translateX.value, 0), MAX_TRANSLATE_X);
+  });
+
+  const panGestureEvent = useAnimatedGestureHandler<
+    PanGestureHandlerGestureEvent,
+    ContextType
+  >({
+    onStart: (_, context) => {
+      context.x = clampedTranslateX.value;
+      cancelAnimation(translateX);
+    },
+    onActive: (event, context) => {
+      translateX.value = event.translationX + context.x;
+    },
+    onEnd: (event) => {
+      translateX.value = withDecay({ velocity: event.velocityX });
+    },
+  });
+
+  return (
+    <View style={styles.container}>
+      <PanGestureHandler onGestureEvent={panGestureEvent}>
+        <Animated.View style={{ flex: 1, flexDirection: 'row' }}>
+          {titles.map((title, index) => {
+            return (
+              <Page
+                key={index.toString()}
+                translateX={clampedTranslateX}
+                index={index}
+                title={title}
+              />
+            );
+          })}
+        </Animated.View>
+      </PanGestureHandler>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+    backgroundColor: '#fff',
+  },
+});

06-scroll-behavior-with-pan-gesture/app.json

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+{
+  "expo": {
+    "name": "06-scroll-behavior-with-pan-gesture",
+    "slug": "06-scroll-behavior-with-pan-gesture",
+    "version": "1.0.0",
+    "orientation": "portrait",
+    "icon": "./assets/icon.png",
+    "splash": {
+      "image": "./assets/splash.png",
+      "resizeMode": "contain",
+      "backgroundColor": "#ffffff"
+    },
+    "updates": {
+      "fallbackToCacheTimeout": 0
+    },
+    "assetBundlePatterns": [
+      "**/*"
+    ],
+    "ios": {
+      "supportsTablet": true
+    },
+    "android": {
+      "adaptiveIcon": {
+        "foregroundImage": "./assets/adaptive-icon.png",
+        "backgroundColor": "#FFFFFF"
+      }
+    },
+    "web": {
+      "favicon": "./assets/favicon.png"
+    }
+  }
+}

06-scroll-behavior-with-pan-gesture/babel.config.js

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+module.exports = function(api) {
+  api.cache(true);
+  return {
+    presets: ['babel-preset-expo'],
+    plugins: ['react-native-reanimated/plugin']
+  };
+};

06-scroll-behavior-with-pan-gesture/components/Page.tsx

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+import React from 'react';
+import { Dimensions, StyleSheet, Text, View } from 'react-native';
+import Animated, { useAnimatedStyle } from 'react-native-reanimated';
+
+interface PageProps {
+  index: number;
+  title: string;
+  translateX: Animated.SharedValue<number>;
+}
+
+const { width: PAGE_WIDTH } = Dimensions.get('window');
+
+const Page: React.FC<PageProps> = ({ index, title, translateX }) => {
+  const pageOffset = PAGE_WIDTH * index;
+
+  const rStyle = useAnimatedStyle(() => {
+    return {
+      transform: [{ translateX: translateX.value + pageOffset }],
+    };
+  });
+
+  return (
+    <Animated.View
+      style={[
+        {
+          ...StyleSheet.absoluteFillObject,
+          backgroundColor: `rgba(0,0,256,0.${index + 2})`,
+          alignItems: 'center',
+          justifyContent: 'center',
+        },
+        rStyle,
+      ]}
+    >
+      <Text
+        style={{
+          fontSize: 70,
+          fontWeight: '700',
+          letterSpacing: 1.5,
+          textTransform: 'uppercase',
+        }}
+      >
+        {title}
+      </Text>
+    </Animated.View>
+  );
+};
+
+export { PAGE_WIDTH };
+export default Page;
+
+const styles = StyleSheet.create({});

06-scroll-behavior-with-pan-gesture/package.json

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+{
+  "main": "node_modules/expo/AppEntry.js",
+  "scripts": {
+    "start": "expo start",
+    "android": "expo start --android",
+    "ios": "expo start --ios",
+    "web": "expo start --web",
+    "eject": "expo eject"
+  },
+  "dependencies": {
+    "expo": "~41.0.1",
+    "expo-status-bar": "~1.0.4",
+    "react": "16.13.1",
+    "react-dom": "16.13.1",
+    "react-native": "https://github.com/expo/react-native/archive/sdk-41.0.0.tar.gz",
+    "react-native-gesture-handler": "^1.10.3",
+    "react-native-reanimated": "^2.2.0",
+    "react-native-web": "~0.13.12"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.9.0",
+    "@types/react": "~16.9.35",
+    "@types/react-native": "~0.63.2",
+    "typescript": "~4.0.0"
+  },
+  "private": true
+}

06-scroll-behavior-with-pan-gesture/tsconfig.json

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+{
+  "extends": "expo/tsconfig.base",
+  "compilerOptions": {
+    "strict": true
+  }
+}