Move away from rnplay to snack, with embedded examples!

Summary:
React Native Playground has been sunset, so I've replaced the examples that previously used it with examples using [Snack](http://snack.expo.io/).

The examples are directly embedded and can be edited live to see updates. The code itself is also in the docs, so we can easily update the docs in one place and we don't have to actually go to a saved app on Snack and update it there.

Run it locally, go to the `Animations` section and the `Direct Manipulation` section.

![screen shot 2017-04-03 at 6 29 51 pm](https://cloud.githubusercontent.com/assets/90494/24638271/ff3ad044-189b-11e7-845d-24b2fb612d95.png)

Open it on your phone, notice that it falls back to just showing plain code.

<img src="https://cloud.githubusercontent.com/assets/90494/24638547/203ec8fc-189e-11e7-99c8-dfabff949f8d.PNG" width="250">

- Get rid of the Expo new user experience dialog that you see when you open a Snack -- is this a dealbreaker
Closes #13285

Differential Revision: D4828011

Pulled By: hramos

fbshipit-source-id: 684ad24a14deb72abb8587ffbb726d316f126d75

Author: brentvatne

docs/Animations.md

@@ -26,34 +26,33 @@ The [`Animated`](docs/animated.html) API is designed to make it very easy to con
 
 For example, a container view that fades in when it is mounted may look like this:
 
-```javascript
-// FadeInView.js
-import React, { Component } from 'react';
-import {
-  Animated,
-} from 'react-native';
+```SnackPlayer
+import React from 'react';
+import { Animated, Text, View } from 'react-native';
 
-class FadeInView extends Component {
-  constructor(props) {
-    super(props);
-    this.state = {
-      fadeAnim: new Animated.Value(0),          // Initial value for opacity: 0
-    };
+class FadeInView extends React.Component {
+  state = {
+    fadeAnim: new Animated.Value(0),  // Initial value for opacity: 0
   }
+
   componentDidMount() {
-    Animated.timing(                            // Animate over time
-      this.state.fadeAnim,                      // The animated value to drive
+    Animated.timing(                  // Animate over time
+      this.state.fadeAnim,            // The animated value to drive
       {
-        toValue: 1,                             // Animate to opacity: 1, or fully opaque
+        toValue: 1,                   // Animate to opacity: 1 (opaque)
+        duration: 10000,              // Make it take a while
       }
-    ).start();                                  // Starts the animation
+    ).start();                        // Starts the animation
   }
+
   render() {
+    let { fadeAnim } = this.state;
+
     return (
-      <Animated.View                            // Special animatable View
+      <Animated.View                 // Special animatable View
         style={{
           ...this.props.style,
-          opacity: this.state.fadeAnim,          // Bind opacity to animated value
+          opacity: fadeAnim,         // Bind opacity to animated value
         }}
       >
         {this.props.children}
@@ -62,23 +61,20 @@ class FadeInView extends Component {
   }
 }
 
-module.exports = FadeInView;
-```
-
-You can then use your `FadeInView` in place of a `View` in your components, like so:
-
-```javascript
-render() {
-  return (
-    <FadeInView style={{width: 250, height: 50, backgroundColor: 'powderblue'}}>
-      <Text style={{fontSize: 28, textAlign: 'center', margin: 10}}>Fading in</Text>
-    </FadeInView>
-  )
+// You can then use your `FadeInView` in place of a `View` in your components:
+export default class App extends React.Component {
+  render() {
+    return (
+      <View style={{flex: 1, alignItems: 'center', justifyContent: 'center'}}>
+        <FadeInView style={{width: 250, height: 50, backgroundColor: 'powderblue'}}>
+          <Text style={{fontSize: 28, textAlign: 'center', margin: 10}}>Fading in</Text>
+        </FadeInView>
+      </View>
+    )
+  }
 }
 ```
 
-![FadeInView](img/AnimatedFadeInView.gif)
-
 Let's break down what's happening here.
 In the `FadeInView` constructor, a new `Animated.Value` called `fadeAnim` is initialized as part of `state`.
 The opacity property on the `View` is mapped to this animated value.
@@ -393,22 +389,29 @@ Note that in order to get this to work on **Android** you need to set the follow
 UIManager.setLayoutAnimationEnabledExperimental && UIManager.setLayoutAnimationEnabledExperimental(true);
 ```
 
-![](img/LayoutAnimationExample.gif)
+```SnackPlayer
+import React from 'react';
+import {
+  NativeModules,
+  LayoutAnimation,
+  Text,
+  TouchableOpacity,
+  StyleSheet,
+  View,
+} from 'react-native';
+
+const { UIManager } = NativeModules;
 
-```javascript
-class App extends React.Component {
-  constructor(props) {
-    super(props);
-    this.state = { w: 100, h: 100 };
-    this._onPress = this._onPress.bind(this);
-  }
+UIManager.setLayoutAnimationEnabledExperimental &&
+  UIManager.setLayoutAnimationEnabledExperimental(true);
 
-  componentWillMount() {
-    // Animate creation
-    LayoutAnimation.spring();
-  }
+export default class App extends React.Component {
+  state = {
+    w: 100,
+    h: 100,
+  };
 
-  _onPress() {
+  _onPress = () => {
     // Animate the update
     LayoutAnimation.spring();
     this.setState({w: this.state.w + 15, h: this.state.h + 15})
@@ -427,8 +430,30 @@ class App extends React.Component {
     );
   }
 }
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+    alignItems: 'center',
+    justifyContent: 'center',
+  },
+  box: {
+    width: 200,
+    height: 200,
+    backgroundColor: 'red',
+  },
+  button: {
+    backgroundColor: 'black',
+    paddingHorizontal: 20,
+    paddingVertical: 15,
+    marginTop: 15,
+  },
+  buttonText: {
+    color: '#fff',
+    fontWeight: 'bold',
+  },
+});
 ```
-[Run this example](https://rnplay.org/apps/uaQrGQ)
 
 This example uses a preset value, you can customize the animations as
 you need, see [LayoutAnimation.js](https://github.com/facebook/react-native/blob/master/Libraries/LayoutAnimation/LayoutAnimation.js)
@@ -457,45 +482,12 @@ We could use this in the Rebound example to update the scale - this
 might be helpful if the component that we are updating is deeply nested
 and hasn't been optimized with `shouldComponentUpdate`.
 
-```javascript
-// Back inside of the App component, replace the scrollSpring listener
-// in componentWillMount with this:
-this._scrollSpring.addListener({
-  onSpringUpdate: () => {
-    if (!this._photo) { return }
-    var v = this._scrollSpring.getCurrentValue();
-    var newProps = {style: {transform: [{scaleX: v}, {scaleY: v}]}};
-    this._photo.setNativeProps(newProps);
-  },
-});
-
-// Lastly, we update the render function to no longer pass in the
-// transform via style (avoid clashes when re-rendering) and to set the
-// photo ref
-render() {
-  return (
-    <View style={styles.container}>
-      <TouchableWithoutFeedback onPressIn={this._onPressIn} onPressOut={this._onPressOut}>
-        <Image ref={component => this._photo = component}
-               source={{uri: "img/ReboundExample.png"}}
-               style={{width: 250, height: 200}} />
-      </TouchableWithoutFeedback>
-    </View>
-  );
-}
-```
-[Run this example](https://rnplay.org/apps/fUqjAg)
-
-It would not make sense to use `setNativeProps` with react-tween-state
-because the updated tween values are set on the state automatically by
-the library - Rebound on the other hand gives us an updated value for
-each frame with the `onSpringUpdate` function.
-
-If you find your animations with dropping frames (performing below 60
-frames per second), look into using `setNativeProps` or
-`shouldComponentUpdate` to optimize them. You may also want to defer any
-computationally intensive work until after animations are complete,
-using the
-[InteractionManager](docs/interactionmanager.html). You
-can monitor the frame rate by using the In-App Developer Menu "FPS
-Monitor" tool.
+If you find your animations with dropping frames (performing below 60 frames
+per second), look into using `setNativeProps` or `shouldComponentUpdate` to
+optimize them. Or you could run the animations on the UI thread rather than
+the JavaScript thread [with the useNativeDriver
+option](http://facebook.github.io/react-native/blog/2017/02/14/using-native-driver-for-animated.html).
+You may also want to defer any computationally intensive work until after
+animations are complete, using the
+[InteractionManager](docs/interactionmanager.html). You can monitor the
+frame rate by using the In-App Developer Menu "FPS Monitor" tool.

docs/DirectManipulation.md

@@ -94,7 +94,10 @@ ReactNativeBaseComponent.js](https://github.com/facebook/react/blob/master/src/r
 Composite components are not backed by a native view, so you cannot call
 `setNativeProps` on them. Consider this example:
 
-```javascript
+```SnackPlayer?name=setNativeProps%20with%20Composite%20Components
+import React from 'react';
+import { Text, TouchableOpacity, View } from 'react-native';
+
 class MyButton extends React.Component {
   render() {
     return (
@@ -105,7 +108,7 @@ class MyButton extends React.Component {
   }
 }
 
-class App extends React.Component {
+export default class App extends React.Component {
   render() {
     return (
       <TouchableOpacity>
@@ -115,7 +118,6 @@ class App extends React.Component {
   }
 }
 ```
-[Run this example](https://rnplay.org/apps/JXkgmQ)
 
 If you run this you will immediately see this error: `Touchable child
 must either be native or forward setNativeProps to a native component`.
@@ -133,9 +135,12 @@ All we need to do is provide a `setNativeProps` method on our component
 that calls `setNativeProps` on the appropriate child with the given
 arguments.
 
-```javascript
+```SnackPlayer?name=Forwarding%20setNativeProps
+import React from 'react';
+import { Text, TouchableOpacity, View } from 'react-native';
+
 class MyButton extends React.Component {
-  setNativeProps(nativeProps) {
+  setNativeProps = (nativeProps) => {
     this._root.setNativeProps(nativeProps);
   }
 
@@ -147,8 +152,17 @@ class MyButton extends React.Component {
     )
   }
 }
+
+export default class App extends React.Component {
+  render() {
+    return (
+      <TouchableOpacity>
+        <MyButton label="Press me!" />
+      </TouchableOpacity>
+    )
+  }
+}
 ```
-[Run this example](https://rnplay.org/apps/YJxnEQ)
 
 You can now use `MyButton` inside of `TouchableOpacity`! A sidenote for
 clarity: we used the [ref callback](https://facebook.github.io/react/docs/more-about-refs.html#the-ref-callback-attribute) syntax here, rather than the traditional string-based ref.
@@ -173,22 +187,22 @@ use `setNativeProps` to directly manipulate the TextInput value when
 necessary. For example, the following code demonstrates clearing the
 input when you tap a button:
 
-```javascript
-class App extends React.Component {
-  constructor(props) {
-    super(props);
-    this.clearText = this.clearText.bind(this);
-  }
+```SnackPlayer?name=Clear%20text
+import React from 'react';
+import { TextInput, Text, TouchableOpacity, View } from 'react-native';
 
-  clearText() {
+export default class App extends React.Component {
+  clearText = () => {
     this._textInput.setNativeProps({text: ''});
   }
 
   render() {
     return (
-      <View style={styles.container}>
-        <TextInput ref={component => this._textInput = component}
-                   style={styles.textInput} />
+      <View style={{flex: 1}}>
+        <TextInput
+          ref={component => this._textInput = component}
+          style={{height: 50, flex: 1, marginHorizontal: 20, borderWidth: 1, borderColor: '#ccc'}}
+        />
         <TouchableOpacity onPress={this.clearText}>
           <Text>Clear text</Text>
         </TouchableOpacity>
@@ -197,17 +211,14 @@ class App extends React.Component {
   }
 }
 ```
-[Run this example](https://rnplay.org/plays/pOI9bA)
 
 ## Avoiding conflicts with the render function
 
 If you update a property that is also managed by the render function,
 you might end up with some unpredictable and confusing bugs because
 anytime the component re-renders and that property changes, whatever
 value was previously set from `setNativeProps` will be completely
-ignored and overridden. [See this example](https://rnplay.org/apps/bp1DvQ)
-for a demonstration of what can happen if these two collide - notice
-the jerky animation each 250ms when `setState` triggers a re-render.
+ignored and overridden.
 
 ## setNativeProps & shouldComponentUpdate
 

website/core/Marked.js

@@ -15,6 +15,7 @@ var Header = require('Header');
 var Prism = require('Prism');
 var React = require('React');
 var WebPlayer = require('WebPlayer');
+var SnackPlayer = require('SnackPlayer');
 
 /**
  * Block-Level Grammar
@@ -842,6 +843,12 @@ Parser.prototype.tok = function() {
         );
       }
 
+      if (lang && lang.indexOf('SnackPlayer') === 0) {
+        return (
+          <SnackPlayer params={lang.split('?')[1]}>{text}</SnackPlayer>
+        );
+      }
+
       return <Prism>{text}</Prism>;
     }
     case 'table': {