leecade / leecade/react-native-swiper

Dynamic slides - working on Ios but not on Android

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JavaScript
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Description

Thank you for your great job, leecade!

I tested the dynamic slides option. It's working perfectly on Ios but not really on Android.
Here an example for your reproduction: swipe to the right is possible only 4 times, left is also restricted.

import React, { Component } from 'react';
import ReactNative, { AppRegistry, StyleSheet, Text, View} from 'react-native';
import Swiper from 'react-native-swiper';

var test = React.createClass({
  getInitialState: function() {
    return {
      // on android swiper starts with last view
      index: (ReactNative.Platform.OS === 'ios') ? 0 : 2,
      // the last active index
      lastIndex: 0,
      // 3 virtual slides
      items: [{},{},{}],
    };
  },
  render: function() {
    return (
      <Swiper
        showsButtons={false}
        showsPagination={false}
        onMomentumScrollEnd={this.onMomentumScrollEnd}>
        {this.state.items.map((item, key) => this.getVirtualView(item, key))}
      </Swiper>
    );
  },
  // gives the direction from last to current slide: prev=-1, next=2, same=0
  diff: function(curIndex, newIndex) {
    var diff=(newIndex-curIndex+3)%3;
    if (diff==2) diff=-1;
    return diff;
  },
  // calc of the new virtual slide index and save last index
  onMomentumScrollEnd: function(e, state, context) {
    var diff = this.diff(this.state.lastIndex, state.index);
    this.setState({lastIndex: state.index});
    this.setState({index: this.state.index+diff});
  },
  // the virtual views only for showing the virtual slide number
  getVirtualView: function(item, key) {
    return (
      <View style={styles.container} key={key}>
        <Text style={styles.welcome}>outerIndex = {this.state.index}</Text>
      </View>
    );
  }
});

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
});

AppRegistry.registerComponent('test', () => test);

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at the Swiper component and trace the Android path around dynamic slide rendering and the onMomentumScrollEnd callback, using the supplied reproduction as the test case. Done means the virtual slides can continue swiping in both directions on Android, with behavior matching iOS.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, react-native
Domain
mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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