Fixes <ViewShot>

README.md

-
 # react-native-view-shot ![](https://img.shields.io/npm/v/react-native-view-shot.svg) ![](https://img.shields.io/badge/react--native-%2040+-05F561.svg)
 
 Capture a React Native view to an image.
 
 ```bash
 yarn add react-native-view-shot
-react-native link react-native-view-shot
 ```
 
 Make sure react-native-view-shot is correctly linked in XCode (might require a manual installation, refer to [React Native doc](https://facebook.github.io/react-native/docs/linking-libraries-ios.html)).
 
+**Before React Native 0.60.x you would have to:**
+
+```bash
+react-native link react-native-view-shot
+```
+
+**Since 0.60.x, [autolink](https://github.com/react-native-community/cli/blob/master/docs/autolinking.md) should just work**, On iOS, you might have to:
+
+```bash
+cd ios && pod install && cd ..
+```
+
 ## Recommended High Level API
 
 ```js
   }
 }
 ```
+
 **Props:**
 
 - **`children`**: the actual content to rasterize.
 captureRef(viewRef, {
   format: "jpg",
   quality: 0.8
-})
-.then(
+}).then(
   uri => console.log("Image saved to", uri),
   error => console.error("Oops, snapshot failed", error)
 );
 
 - **`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` or `webm` (Android). Defaults to `png`.
-  - **`quality`** *(number)*: the quality. 0.0 - 1.0 (default). (only available on lossy formats like jpg)
-  - **`result`** *(string)*, the method you want to use to save the snapshot, one of:
-    - `"tmpfile"` (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*.
+  - **`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` or `webm` (Android). Defaults to `png`.
+  - **`quality`** _(number)_: the quality. 0.0 - 1.0 (default). (only available on lossy formats like jpg)
+  - **`result`** _(string)_, the method you want to use to save the snapshot, one of:
+    - `"tmpfile"` (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](https://en.wikipedia.org/wiki/Data_URI_scheme) header.
-  - **`snapshotContentContainer`** *(bool)*: if true and when view is a ScrollView, the "content container" height will be evaluated instead of the container height.
+  - **`snapshotContentContainer`** _(bool)_: if true and when view is a ScrollView, the "content container" height will be evaluated instead of the container height.
 
 ## `releaseCapture(uri)`
 
 captureScreen({
   format: "jpg",
   quality: 0.8
-})
-.then(
+}).then(
   uri => console.log("Image saved to", uri),
   error => console.error("Oops, snapshot failed", error)
 );
 ```
 
-This method will capture the contents of the currently displayed screen as a native hardware screenshot. It does not require a ref input, as it does not work at the view level. This means that ScrollViews will not be captured in their entirety - only the portions currently visible to the user. 
+This method will capture the contents of the currently displayed screen as a native hardware screenshot. It does not require a ref input, as it does not work at the view level. This means that ScrollViews will not be captured in their entirety - only the portions currently visible to the user.
 
 Returns a Promise of the image URI.
 
 
 Model tested: iPhone 6 (iOS), Nexus 5 (Android).
 
-| System             | iOS                | Android           | Windows           |
-|--------------------|--------------------|-------------------|-------------------|
-| View,Text,Image,.. | YES                | YES               | YES               |                    
-| WebView            | YES                | YES<sup>1</sup>   | YES               |
-| gl-react v2        | YES                | NO<sup>2</sup>    | NO<sup>3</sup>    |
-| react-native-video | NO                 | NO                | NO                |
-| react-native-maps  | YES                | NO<sup>4</sup>    | NO<sup>3</sup>    |
-| react-native-svg   | YES                | YES               | maybe?            |
-| react-native-camera   | NO                | YES               | NO <sup>3</sup>        |
+| System                | iOS              | Android           | Windows                |
+| --------------------- | ---------------- | ----------------- | ---------------------- |
+| View,Text,Image,..    | YES              | YES               | YES                    |
+| WebView               | YES              | YES<sup>1</sup>   | YES                    |
+| gl-react v2           | YES              | NO<sup>2</sup>    | NO<sup>3</sup>         |
+| react-native-video    | NO               | NO                | NO                     |
+| react-native-maps     | YES              | NO<sup>4</sup>    | NO<sup>3</sup>         |
+| react-native-svg      | YES              | YES               | maybe?                 |
+| react-native-camera   | NO               | YES               | NO <sup>3</sup>        |
 
 >
+
 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.
 ## Performance Optimization
 
 During profiling captured several things that influence on performance:
-1) (de-)allocation of memory for bitmap
-2) (de-)allocation of memory for Base64 output buffer
-3) compression of bitmap to different image formats: PNG, JPG
+
+1. (de-)allocation of memory for bitmap
+2. (de-)allocation of memory for Base64 output buffer
+3. compression of bitmap to different image formats: PNG, JPG
 
 To solve that in code introduced several new approaches:
+
 - reusable images, that reduce load on GC;
 - reusable arrays/buffers that also reduce load on GC;
 - RAW image format for avoiding expensive compression;
 Introduced a new image format RAW. it correspond a ARGB array of pixels.
 
 Advantages:
+
 - no compression, so its supper quick. Screenshot taking is less than 16ms;
 
 RAW format supported for `zip-base64`, `base64` and `tmpfile` result types.
 ### How to work with zip-base64 and RAW format?
 
 ```js
-const fs = require('fs')
-const zlib = require('zlib')
-const PNG = require('pngjs').PNG
-const Buffer = require('buffer').Buffer
+const fs = require("fs");
+const zlib = require("zlib");
+const PNG = require("pngjs").PNG;
+const Buffer = require("buffer").Buffer;
 
-const format = Platform.OS === 'android' ? 'raw' : 'png'
-const result = Platform.OS === 'android' ? 'zip-base64' : 'base64'
+const format = Platform.OS === "android" ? "raw" : "png";
+const result = Platform.OS === "android" ? "zip-base64" : "base64";
 
 captureRef(this.ref, { result, format }).then(data => {
-    // expected pattern 'width:height|', example: '1080:1731|'
-    const resolution = /^(\d+):(\d+)\|/g.exec(data)
-    const width = (resolution || ['', 0, 0])[1]
-    const height = (resolution || ['', 0, 0])[2]
-    const base64 = data.substr((resolution || [''])[0].length || 0)
-
-    // convert from base64 to Buffer
-    const buffer = Buffer.from(base64, 'base64')
-    // un-compress data
-    const inflated = zlib.inflateSync(buffer)
-    // compose PNG
-    const png = new PNG({ width, height })
-    png.data = inflated
-    const pngData = PNG.sync.write(png)
-    // save composed PNG
-    fs.writeFileSync(output, pngData)
-})
+  // expected pattern 'width:height|', example: '1080:1731|'
+  const resolution = /^(\d+):(\d+)\|/g.exec(data);
+  const width = (resolution || ["", 0, 0])[1];
+  const height = (resolution || ["", 0, 0])[2];
+  const base64 = data.substr((resolution || [""])[0].length || 0);
+
+  // convert from base64 to Buffer
+  const buffer = Buffer.from(base64, "base64");
+  // un-compress data
+  const inflated = zlib.inflateSync(buffer);
+  // compose PNG
+  const png = new PNG({ width, height });
+  png.data = inflated;
+  const pngData = PNG.sync.write(png);
+  // save composed PNG
+  fs.writeFileSync(output, pngData);
+});
 ```
 
 Keep in mind that packaging PNG data is a CPU consuming operation as a `zlib.inflate`.
 > Note: code is tested in large commercial project.
 
 > Note #2: Don't forget to add packages into your project:
+>
 > ```js
 > yarn add pngjs
 > yarn add zlib
 
 This is because the snapshot image result is in real pixel size where the width/height defined in a React Native style are defined in "point" unit. You might want to set width and height option to force a resize. (might affect image quality)
 
-
 ---
 
 ## Thanks

RNViewShot.podspec

-require 'json'
-version = JSON.parse(File.read('package.json'))["version"]
-
-Pod::Spec.new do |s|
-
-  s.name           = "RNViewShot"
-  s.version        = version
-  s.summary        = "Capture a React Native view to an image"
-  s.homepage       = "https://github.com/gre/react-native-view-shot"
-  s.license        = "MIT"
-  s.author         = { "Gaëtan Renaudeau" => "renaudeau.gaetan@gmail.com" }
-  s.platform       = :ios, "7.0"
-  s.source         = { :git => "https://github.com/gre/react-native-view-shot.git", :tag => "v#{s.version}" }
-  s.source_files   = 'ios/*.{h,m}'
-  s.preserve_paths = "**/*.js"
-  s.dependency 'React'
-
-end

package.json

     "rasterize"
   ],
   "author": "Gaëtan Renaudeau <renaudeau.gaetan@gmail.com>",
+  "homepage": "https://github.com/gre/react-native-view-shot",
   "license": "MIT",
   "repository": {
     "type": "git",

react-native-view-shot.podspec

+require 'json'
+
+package = JSON.parse(File.read(File.join(__dir__, 'package.json')))
+
+Pod::Spec.new do |s|
+  s.name         = package['name']
+  s.version      = package['version']
+  s.summary      = package['description']
+  s.license      = package['license']
+
+  s.authors      = package['author']
+  s.homepage     = package['homepage']
+  s.platform     = :ios, "9.0"
+
+  s.source       = { :git => "https://github.com/gre/react-native-view-shot.git", :tag => "v#{s.version}" }
+  s.source_files  = "ios/**/*.{h,m}"
+
+  s.dependency 'React'
+end
+

src/index.js

 import { View, NativeModules, Platform, findNodeHandle } from "react-native";
 const { RNViewShot } = NativeModules;
 
-import type { Element, ElementRef, ElementType, Ref } from 'react';
-import type { ViewStyleProp } from 'StyleSheet';
-import type { LayoutEvent } from 'CoreEventTypes';
+import type { Element, ElementRef, ElementType, Ref } from "react";
+import type { ViewStyleProp } from "StyleSheet";
+import type { LayoutEvent } from "CoreEventTypes";
 
 const neverEndingPromise = new Promise(() => {});
 
 
 if (!RNViewShot) {
   console.warn(
-    "NativeModules.RNViewShot is undefined. Make sure the library is linked on the native side."
+    "react-native-view-shot: NativeModules.RNViewShot is undefined. Make sure the library is linked on the native side."
   );
 }
 
   if (acceptedFormats.indexOf(options.format) === -1) {
     options.format = defaultOptions.format;
     errors.push(
-      "option format '" + options.format + "' is not in valid formats: " + acceptedFormats.join(" | ")
+      "option format '" +
+        options.format +
+        "' is not in valid formats: " +
+        acceptedFormats.join(" | ")
     );
   }
   if (acceptedResults.indexOf(options.result) === -1) {
     options.result = defaultOptions.result;
     errors.push(
-      "option result '" + options.result  + "' is not in valid formats: " + acceptedResults.join(" | ")
+      "option result '" +
+        options.result +
+        "' is not in valid formats: " +
+        acceptedResults.join(" | ")
     );
   }
   return { options, errors };
 }
 
+export function ensureModuleIsLoaded() {
+  if (!RNViewShot) {
+    throw new Error(
+      "react-native-view-shot: NativeModules.RNViewShot is undefined. Make sure the library is linked on the native side."
+    );
+  }
+}
+
 export function captureRef<T: ElementType>(
   view: number | ?View | Ref<T>,
   optionsObject?: Object
 ): Promise<string> {
-  if (view && typeof view === "object" && "current" in view && view.current) { // React.RefObject
+  ensureModuleIsLoaded();
+  if (view && typeof view === "object" && "current" in view && view.current) {
+    // React.RefObject
     view = view.current;
+    if (!view) {
+      return Promise.reject(new Error("ref.current is null"));
+    }
   }
   if (typeof view !== "number") {
     const node = findNodeHandle(view);
-    if (!node)
+    if (!node) {
       return Promise.reject(
         new Error("findNodeHandle failed to resolve view=" + String(view))
       );
+    }
     view = node;
   }
   const { options, errors } = validateOptions(optionsObject);
   }
 }
 
-export function captureScreen(
-  optionsObject?: Options
-): Promise<string> {
+export function captureScreen(optionsObject?: Options): Promise<string> {
+  ensureModuleIsLoaded();
   const { options, errors } = validateOptions(optionsObject);
   if (__DEV__ && errors.length > 0) {
     console.warn(
   static captureRef = captureRef;
   static releaseCapture = releaseCapture;
   constructor(props) {
-    super(props)
-    this.state={}
+    super(props);
+    this.state = {};
   }
   root: ?View;
 
     }
   }
 
-  static getDerivedStateFromProps(props, state) {
-    if(props.captureMode !== undefined) {
-      if (props.captureMode !== this.props.captureMode) {
-        this.syncCaptureLoop(props.captureMode);
+  componentDidUpdate(prevProps) {
+    if (this.props.captureMode !== undefined) {
+      if (this.props.captureMode !== prevProps.captureMode) {
+        this.syncCaptureLoop(this.props.captureMode);
       }
     }
-    return null;
-  }
-
-  componentDidUpdate() {
     if (this.props.captureMode === "update") {
       this.capture();
     }
   render() {
     const { children } = this.props;
     return (
-      <View ref={this.onRef} collapsable={false} onLayout={this.onLayout} style={this.props.style}>
+      <View
+        ref={this.onRef}
+        collapsable={false}
+        onLayout={this.onLayout}
+        style={this.props.style}
+      >
         {children}
       </View>
     );

yarn.lock

+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+