react-native-view-shot/README.md

react-native-view-shot

Capture a React Native view to an image.

iOS: For React Native version between 0.30.x and 0.39.x, you should use react-native-view-shot@1.5.1.

Usage

import { takeSnapshot } from "react-native-view-shot";

takeSnapshot(viewRef, {
  format: "jpeg",
  quality: 0.8
})
.then(
  uri => console.log("Image saved to", uri),
  error => console.error("Oops, snapshot failed", error)
);

Example

Checkout react-native-view-shot-example

Full API

takeSnapshot(view, options)

Returns a Promise of the image URI.

• view is a reference to a React Native component.
• options may include:
  • width / height (number): the width and height of the final image (resized from the View bound. don’t provide it if you want the original pixel size).
  • format (string): either png or jpg/jpeg or webm (Android). Defaults to png.
  • quality (number): the quality. 0.0 - 1.0 (default). (only available on lossy formats like jpeg)
  • result (string), the method you want to use to save the snapshot, one of:
  • "file" (default): save to a temporary file (that will only exist for as long as the app is running).
  • "base64": encode as base64 and returns the raw string. Use only with small images as this may result of lags (the string is sent over the bridge). N.B. This is not a data uri, use data-uri instead.
  • "data-uri": same as base64 but also includes the Data URI scheme header.
  • path (string): The absolute path where the file get generated. Read below before using it!
  • snapshotContentContainer (bool): if true and when view is a ScrollView, the “content container” height will be evaluated instead of the container height.

path option and dirs constants

IMPORTANT: We might actually drop the path feature because of its complexity in the current codebase (and bugs that are not fixed), please consider using react-native-view-shot with https://github.com/itinance/react-native-fs to solve this.

By default, takeSnapshot will export in a temporary folder and the snapshot file will be deleted as soon as the app leaves. But if you use the path option, you make the snapshot file more permanent and at a specific file location. it is up to you to manage the image file lifecycle, the library won’t clean it for you (which might result of leaking files on user’s phone if you are not careful). There is also no guarantee the file will be successfully saved: you can reach permissions problem, this also is platform specific.

If you still want to do this, we expose a few somewhat universal “constants” to ease the work.

import { takeSnapshot, dirs } from "react-native-view-shot";
// cross platform dirs:
const { CacheDir, DocumentDir, MainBundleDir, MovieDir, MusicDir, PictureDir } = dirs;
// only available Android:
const { DCIMDir, DownloadDir, RingtoneDir, SDCardDir } = dirs;

takeSnapshot(viewRef, { path: PictureDir+"/foo.png" })
.then(
  uri => console.log("Image saved to", uri),
  error => console.error("Oops, snapshot failed", error)
);

Interoperability Table

Model tested: iPhone 6 (iOS), Nexus 5 (Android).

System	iOS	Android	Windows
View,Text,Image,..	YES	YES	YES
WebView	YES	YES1	YES
gl-react v2	YES	NO2	NO3
react-native-video	NO	NO	NO
react-native-maps	YES	NO4	NO3

1. Only supported by wrapping a <View collapsable={false}> parent and snapshotting it.
2. It returns an empty image (not a failure Promise).
3. Component itself lacks platform support.
4. But you can just use the react-native-maps snapshot function: https://github.com/airbnb/react-native-maps#take-snapshot-of-map

Caveats

Snapshots are not guaranteed to be pixel perfect. It also depends on the platform. Here is some difference we have noticed and how to workaround.

• Support of special components like Video / GL views is not guaranteed to work. In case of failure, the takeSnapshot promise gets rejected (the library won’t crash).
• It’s preferable to use a background color on the view you rasterize to avoid transparent pixels and potential weirdness that some border appear around texts.

specific to Android implementation

• you need to make sure collapsable is set to false if you want to snapshot a View. Some content might even need to be wrapped into such <View collapsable={false}> to actually make them snapshotable! Otherwise that view won’t reflect any UI View. (found by @gaguirre)
• if you implement a third party library and want to get back a File, you must first resolve the Uri. (the file result returns an Uri so it’s consistent with iOS and can be given to APIs like Image.getSize)

Getting started

npm install --save react-native-view-shot

Mostly automatic installation

react-native link react-native-view-shot

Manual installation

iOS

1. In XCode, in the project navigator, right click Libraries ➜ Add Files to [your project's name]
2. Go to node_modules ➜ react-native-view-shot and add RNViewShot.xcodeproj
3. In XCode, in the project navigator, select your project. Add libRNViewShot.a to your project’s Build Phases ➜ Link Binary With Libraries
4. Run your project (Cmd+R)<

Android

1. Open up android/app/src/main/java/[...]/MainActivity.java
   • Add import fr.greweb.reactnativeviewshot.RNViewShotPackage; to the imports at the top of the file
   • Add new RNViewShotPackage() to the list returned by the getPackages() method
2. Append the following lines to android/settings.gradle: include ':react-native-view-shot' project(':react-native-view-shot').projectDir = new File(rootProject.projectDir, '../node_modules/react-native-view-shot/android')
3. Insert the following lines inside the dependencies block in android/app/build.gradle: compile project(':react-native-view-shot')

Windows

1. In Visual Studio, in the solution explorer, right click on your solution then select Add ➜ ExisitingProject
2. Go to node_modules ➜ react-native-view-shot and add RNViewShot.csproj (UWP) or optionally RNViewShot.Net46.csproj (WPF)
3. In Visual Studio, in the solution explorer, right click on your Application project then select Add ➜ Reference
4. Under the projects tab select RNViewShot (UWP) or RNViewShot.Net46 (WPF)

Thanks

• To initial iOS work done by @jsierles in https://github.com/jsierles/react-native-view-snapshot
• To React Native implementation of takeSnapshot in iOS by @nicklockwood
• To Windows implementation by @ryanlntn