README.md

React Native Parallax Swiper

Configurable parallax swiper based on an iOS pattern.

Features

• Flexible. Share one Animated.Value between ParallaxSwiper and your own UI.
• Performant. Runs on the native thread for 60FPS with no latency.
• Cross-platform. Works on both iOS and Android.
• Progress Bar. Horizontal or vertical progress bar.

Examples

Clone this repo and:

$ cd examples/ParallaxSwiperExample
$ npm install
$ react-native link
$ react-native run-ios

Installation

$ npm install react-native-parallax-swiper --save

Usage

import React from "react";
import {
  Animated,
  Text,
  View,
  Image,
  StyleSheet,
  Dimensions
} from "react-native";

import {
  ParallaxSwiper,
  ParallaxSwiperPage
} from "react-native-parallax-swiper";

const { width, height } = Dimensions.get("window");

export default class App extends React.Component {
  myCustomAnimatedValue = new Animated.Value(0);

  getPageTransformStyle = index => ({
    transform: [
      {
        scale: this.myCustomAnimatedValue.interpolate({
          inputRange: [
            (index - 1) * (width + 8), // Add 8 for dividerWidth
            index * (width + 8),
            (index + 1) * (width + 8)
          ],
          outputRange: [0, 1, 0],
          extrapolate: "clamp"
        })
      },
      {
        rotate: this.myCustomAnimatedValue.interpolate({
          inputRange: [
            (index - 1) * (width + 8),
            index * (width + 8),
            (index + 1) * (width + 8)
          ],
          outputRange: ["180deg", "0deg", "-180deg"],
          extrapolate: "clamp"
        })
      }
    ]
  });

  render() {
    return (
      <ParallaxSwiper
        speed={0.5}
        animatedValue={this.myCustomAnimatedValue}
        dividerWidth={8}
        dividerColor="black"
        backgroundColor="black"
        onMomentumScrollEnd={activePageIndex => console.log(activePageIndex)}
        showProgressBar={true}
        progressBarBackgroundColor="rgba(0,0,0,0.25)"
        progressBarValueBackgroundColor="white"
      >
        <ParallaxSwiperPage
          BackgroundComponent={
            <Image
              style={styles.backgroundImage}
              source={{ uri: "https://goo.gl/wtHtxG" }}
            />
          }
          ForegroundComponent={
            <View style={styles.foregroundTextContainer}>
              <Animated.Text
                style={[styles.foregroundText, this.getPageTransformStyle(0)]}
              >
                Page 1
              </Animated.Text>
            </View>
          }
        />
        <ParallaxSwiperPage
          BackgroundComponent={
            <Image
              style={styles.backgroundImage}
              source={{ uri: "https://goo.gl/gt4rWa" }}
            />
          }
          ForegroundComponent={
            <View style={styles.foregroundTextContainer}>
              <Animated.Text
                style={[styles.foregroundText, this.getPageTransformStyle(1)]}
              >
                Page 2
              </Animated.Text>
            </View>
          }
        />
        <ParallaxSwiperPage
          BackgroundComponent={
            <Image
              style={styles.backgroundImage}
              source={{ uri: "https://goo.gl/KAaVXt" }}
            />
          }
          ForegroundComponent={
            <View style={styles.foregroundTextContainer}>
              <Animated.Text
                style={[styles.foregroundText, this.getPageTransformStyle(2)]}
              >
                Page 3
              </Animated.Text>
            </View>
          }
        />
      </ParallaxSwiper>
    );
  }
}

const styles = StyleSheet.create({
  backgroundImage: {
    width,
    height
  },
  foregroundTextContainer: {
    flex: 1,
    alignItems: "center",
    justifyContent: "center",
    backgroundColor: "transparent"
  },
  foregroundText: {
    fontSize: 34,
    fontWeight: "700",
    letterSpacing: 0.41,
    color: "white"
  }
});

ParallaxSwiper Props

Prop	Type	Default	Description
speed	Number	0.25	This number determines how fast BackgroundComponent moves. Set to 0 for no movement at all, set to 1 and background will move as fast as the scroll.
dividerWidth	Number	8	The width of the divider between each page. (horizontal only)
dividerColor	String	black	Color of divider.
backgroundColor	String	black	ParallaxSwiper’s background color.
scrollToIndex	Number	0	Scroll to page with a smooth animation. Note: You need to use state if you want to change index any other time than when component is rendered.
onMomentumScrollEnd	Function	N/A	Fired when ScrollView stops scrolling and is passed the current page index.
animatedValue	Number (Animated.Value)	0	Optionally pass a new instance of Animated.Value to access the animated value outside of ParallaxSwiper.
vertical	Boolean	false	When true, ParallaxSwiper’s children are arranged vertically in a column instead of horizontally in a row. For now only iOS supports this.
showsHorizontalScrollIndicator	Boolean	false	When true, shows a horizontal scroll indicator. The default value is false.
showsVerticalScrollIndicator	Boolean	false	When true, shows a vertical scroll indicator. The default value is false.
children	React component (ParallaxSwiperPage)	N/A	Each top-level ParallaxSwiperPage child.
showProgressBar	Boolean	false	When true, a progress bar will render on bottom for horizontal and left on vertical.
progressBarThickness	Number	4	Thickness translates to height for horizontal and width for vertical progress bar.
progressBarBackgroundColor	String	rgba(255,255,255,0.25)	Background color of progress bar background.
progressBarValueBackgroundColor	String	white	Background color of progress bar value background.

ParallaxSwiperPage Props

Prop	Type	Default	Description
BackgroundComponent	React element	N/A	This component will render in the background of the page and will be animated based on scroll.
ForegroundComponent	React element	N/A	This component will render in the foreground of the page.

TODO

• Create Expo demos
• Create examples
• Expose current index
• Support scrollToIndex
• Fix Android
• Expose Animated.Value for animation outside of ParallaxSwiper
• Add drag effects e.g. zoom, blur, darken
• Expose rest of ScrollView props
• Use FlatList instead of ScrollView

Why another parallax component? 😒

This component is inspired by an iOS pattern that no react-native-parallax-whatever previously delivered. It emulates this pattern by using the ScrollView component which has features like velocity, paging, and platform specific easing curves; It also has optional dividers to split up each page. You can see this pattern in apps like iOS Camera Roll, Twitter Moments, Kylie Jenner’s app, Vevo’s app, and more.

Contributors

Chris LeBlanc [💻]

Questions or suggestions?

Hit me up on Twitter, or create an issue.

Copyright

Copyright (c) 2017 Zachary Gibson Licensed under the MIT license.