109 lines
3.2 KiB
JavaScript
109 lines
3.2 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule AnExChained
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* @flow
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*/
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'use strict';
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var React = require('react');
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var ReactNative = require('react-native');
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var {
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Animated,
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PanResponder,
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StyleSheet,
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View,
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} = ReactNative;
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class AnExChained extends React.Component<Object, any> {
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constructor(props: Object) {
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super(props);
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this.state = {
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stickers: [new Animated.ValueXY()], // 1 leader
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};
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var stickerConfig = {tension: 2, friction: 3}; // soft spring
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for (var i = 0; i < 4; i++) { // 4 followers
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var sticker = new Animated.ValueXY();
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Animated.spring(sticker, {
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...stickerConfig,
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toValue: this.state.stickers[i], // Animated toValue's are tracked
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}).start();
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this.state.stickers.push(sticker); // push on the followers
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}
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var releaseChain = (e, gestureState) => {
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this.state.stickers[0].flattenOffset(); // merges offset into value and resets
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Animated.sequence([ // spring to start after decay finishes
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Animated.decay(this.state.stickers[0], { // coast to a stop
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velocity: {x: gestureState.vx, y: gestureState.vy},
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deceleration: 0.997,
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}),
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Animated.spring(this.state.stickers[0], {
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toValue: {x: 0, y: 0} // return to start
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}),
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]).start();
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};
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this.state.chainResponder = PanResponder.create({
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onStartShouldSetPanResponder: () => true,
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onPanResponderGrant: () => {
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this.state.stickers[0].stopAnimation((value) => {
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this.state.stickers[0].setOffset(value); // start where sticker animated to
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this.state.stickers[0].setValue({x: 0, y: 0}); // avoid flicker before next event
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});
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},
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onPanResponderMove: Animated.event(
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[null, {dx: this.state.stickers[0].x, dy: this.state.stickers[0].y}] // map gesture to leader
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),
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onPanResponderRelease: releaseChain,
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onPanResponderTerminate: releaseChain,
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});
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}
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render() {
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return (
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<View style={styles.chained}>
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{this.state.stickers.map((_, i) => {
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var j = this.state.stickers.length - i - 1; // reverse so leader is on top
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var handlers = (j === 0) ? this.state.chainResponder.panHandlers : {};
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return (
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<Animated.Image
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{...handlers}
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key={i}
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source={CHAIN_IMGS[j]}
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style={[styles.sticker, {
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transform: this.state.stickers[j].getTranslateTransform(), // simple conversion
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}]}
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/>
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);
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})}
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</View>
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);
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}
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}
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var styles = StyleSheet.create({
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chained: {
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alignSelf: 'flex-end',
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top: -160,
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right: 126
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},
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sticker: {
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position: 'absolute',
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height: 120,
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width: 120,
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backgroundColor: 'transparent',
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},
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});
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var CHAIN_IMGS = [
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require('../hawk.png'),
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require('../bunny.png'),
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require('../relay.png'),
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require('../hawk.png'),
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require('../bunny.png')
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];
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module.exports = AnExChained;
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