Add showPreview instance method

Fixes cookpete/react-player#679

README.md

@@ -167,6 +167,7 @@ Method | Description
 `getSecondsLoaded()` | Returns the number of seconds that have been loaded<br />&nbsp; ◦ &nbsp;Returns `null` if unavailable or unsupported
 `getDuration()` | Returns the duration (in seconds) of the currently playing media<br />&nbsp; ◦ &nbsp;Returns `null` if duration is unavailable
 `getInternalPlayer()` | Returns the internal player of whatever is currently playing<br />&nbsp; ◦ &nbsp;eg the [YouTube player instance](https://developers.google.com/youtube/iframe_api_reference#Loading_a_Video_Player), or the [`<video>`](https://developer.mozilla.org/en/docs/Web/HTML/Element/video) element when playing a video file<br />&nbsp; ◦ &nbsp;Use `getInternalPlayer('hls')` to get the [hls.js](https://github.com/video-dev/hls.js) player<br />&nbsp; ◦ &nbsp;Use `getInternalPlayer('dash')` to get the [dash.js](https://github.com/Dash-Industry-Forum/dash.js) player<br />&nbsp; ◦ &nbsp;Returns `null` if the internal player is unavailable
+`showPreview()` | When using `light` mode, returns to the preview overlay
 
 ### Advanced Usage
 

src/ReactPlayer.js

@@ -64,6 +64,9 @@ export default class ReactPlayer extends Component {
   onClickPreview = () => {
     this.setState({ showPreview: false })
   }
+  showPreview = () => {
+    this.setState({ showPreview: true })
+  }
   getDuration = () => {
     if (!this.player) return null
     return this.player.getDuration()

src/demo/App.js

@@ -171,6 +171,9 @@ class App extends Component {
                 <button onClick={this.stop}>Stop</button>
                 <button onClick={this.playPause}>{playing ? 'Pause' : 'Play'}</button>
                 <button onClick={this.onClickFullscreen}>Fullscreen</button>
+                {light &&
+                  <button onClick={() => this.player.showPreview()}>Show preview</button>
+                }
                 {ReactPlayer.canEnablePIP(url) &&
                   <button onClick={this.togglePIP}>{pip ? 'Disable PiP' : 'Enable PiP'}</button>
                 }