oblongmana / react-native-responsive-image

Responsive image component for React Native

React Native Responsive Image

React Native <Image> component, that rescales itselfs correctly on iOS and Android devices.

##Why?

React Native's Image size is rendered the same regardless of device size and resolution. Desired behaviour in is to have a component, that scales appropriately.

##Installation

npm install react-native-responsive-image --save

##Usage

Use the <ResponsiveImage> component and set it's initWidth and initHeight props.

These values are used as they are for iPhone6 Plus, and they are scaled down on any smaller iOS/Android device.

##Example

Three images in one full-width row:

import React, { Component } from 'react';
import { AppRegistry, StyleSheet, View } from 'react-native';
import ResponsiveImage from 'react-native-responsive-image';

class App extends Component {
  render() {
    return (
      <View style={{flex: 1, justifyContent: 'center',}}>
                <View style={{flexDirection: 'row',}}>
                    <ResponsiveImage source={{uri: 'https://facebook.github.io/react/img/logo_og.png'}} initWidth="138" initHeight="138"/>
                    <ResponsiveImage source={{uri: 'https://facebook.github.io/react/img/logo_og.png'}} initWidth="138" initHeight="138"/>
                    <ResponsiveImage source={{uri: 'https://facebook.github.io/react/img/logo_og.png'}} initWidth="138" initHeight="138"/>
                </View>
            </View>
    );
  }
}

AppRegistry.registerComponent('ResponsiveImageExample', () => App);

##One image size?

We could have added support for multiple image sources, like https://github.com/exponentjs/react-native-responsive-image has. It sounds like you would save some bytes by delivering less-resolution images to devices with lower resolution.

But solution that worked the best for me was different. Actually you need to serve just one high-resolution compressed, and it will even save more bytes. Though @2x or @3x images have more pixels, it’s surprising how much they can be compressed.

##Example project

###Create project

react-native init ResponsiveImageExample

cp ./example/index.android.js ./ResponsiveImageExample/index.android.js

cp ./example/index.ios.js ./ResponsiveImageExample/index.ios.js

cd ResponsiveImageExample

npm i react-native-responsive-image

###Run on iOS

Open ResponsiveImageExample/ios/ResponsiveImageExample.xcodeproj

Run the project inside iOS Simulator simulator

###Run on Android

Go to ResponsiveImageExample

react-native run-android

##Development

1. Modify react-native-responsive-image.js in the root directory

2. Propagate changes cp ./react-native-responsive-image.js ./ResponsiveImageExample/node_modules/react-native-responsive-image/react-native-responsive-image.js