@silvermine/videojs-chromecast/README.md

video.js plugin for casting to chromecast

# Silvermine VideoJS Chromecast Plugin

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## What is it?

A plugin for [videojs](http://videojs.com/) versions 6+ that adds a button to the control
bar which will cast videos to a Chromecast.


## How do I use it?

The `@silvermine/videojs-chromecast` plugin includes 3 types of assets: JavaScript, CSS,
and images.

You can either build the plugin locally and use the assets that are output from the build
process directly, or you can install the plugin as an NPM module, include the
JavaScript and SCSS source in your project using a Common-JS module loader and SASS build
process, and copy the images from the image source folder to your project.

Note that regardless of whether you are using this plugin via the pre-built JS or as a
module, the Chromecast framework will need to be included after the plugin. For example:

```html
<script src="https://unpkg.com/video.js@6.1.0/dist/video.js"></script>
<script src="./dist/silvermine-videojs-chromecast.min.js"></script>
<script type="text/javascript" src="https://www.gstatic.com/cv/js/sender/v1/cast_sender.js?loadCastFramework=1"></script>
```

### Building the plugin locally

   1. Either clone this repository or install the `@silvermine/videojs-chromecast` module
      using `npm install @silvermine/videojs-chromecast`.
   2. Ensure that `@silvermine/videojs-chromecast`'s `devDependencies` are installed by
      running `npm install` from within the `videojs-chromecast` folder.
   3. Run `grunt build` to build and copy the JavaScript, CSS and image files to the
      `videojs-chromecast/dist` folder.
   4. Copy the plugin's files from the `dist` folder into your project as needed.
   5. Ensure that the images in the `dist/images` folder are accessible at `./images/`,
      relative to where the plugin's CSS is located. If, for example, your CSS is located
      at `https://example.com/plugins/silvermine-videojs-chromecast.css`, then the
      plugin's images should be located at `https://example.com/plugins/images/`.
   6. Follow the steps in the "Configuration" section below.

Note: when adding the plugin's JavaScript to your web page, include the
`silvermine-videojs-chromecast.min.js` JavaScript file in your HTML *after* loading
Video.js. The plugin's built JavaScript file expects there to be a reference to Video.js
at `window.videojs` and will throw an error if it does not exist.

### Initialization options

   * **`preloadWebComponents`** (default: `false`) - The Chromecast framework relies on
     the `webcomponents.js` polyfill when a browser does not have
     `document.registerElement` in order to create the `<google-cast-button>` custom
     component (which is not used by this plugin).  If you are using jQuery, this polyfill
     must be loaded and initialized before jQuery is initialized. Unfortunately, the
     Chromecast framework loads the `webcomponents.js` polyfill via a dynamically created
     `<script>` tag. This causes a race condition (see #17). Also, including
     `webcomponents.js` anywhere on the page will break jQuery's fix for bubbling some
     events to `document` (e.g. `onchange` events for `<select>`, see #21).  Setting
     `preloadWebComponents` to `true` will "fix" these 2 problems by (1) making this
     plugin add the `webcomponents` polyfill synchronously when the polyfill is needed and
     (2) using the `webcomponents-lite.js` version as it does not include the shadow DOM
     polyfills, but still provides the `registerElement` polyfill that the Chromecast
     framework needs. If you use the `preloadWebComponents: true` option, you should make
     sure that this plugin is loaded before jQuery. Then include the Chromecast framework
     after this plugin as you normally would.

     **Note:** There is a caveat to using the `preloadWebComponents` setting. Because the
     Chromecast plugin uses the shadow DOM to create the `<google-cast-button>` custom
     component, **the `<google-cast-button>` custom component may partly render, but it
     will not be functional**. This tag is not used by this plugin. However if you must
     use this tag elsewhere, you should not use the `preloadWebComponents` flag.

     tl;dr: if you use jQuery, you should use the `preloadWebComponents: true` option in
     this plugin.

#### Providing initialization options via `require()`

If requiring this plugin via NPM, any desired initialization options can be supplied to
the constructor function exported by the module. For example:

```js
require('@silvermine/videojs-chromecast')(videojs, { preloadWebComponents: true });
```

#### Providing initialization options via `<script>`

If using the prebuilt JS, the initialization options can be provided via
`window.SILVERMINE_VIDEOJS_CHROMECAST_CONFIG`. Note that these options need to be set
before the `<script>` tag to include the plugin.

```html
<script>
   window.SILVERMINE_VIDEOJS_CHROMECAST_CONFIG = {
      preloadWebComponents: true,
   };
</script>
<script src="path/to/silvermine-videojs-chromecast.js"></script>
```

### Configuration

Once the plugin has been loaded and registered, configure it and add it to your Video.js
player using Video.js' plugin configuration option (see the section under the heading
"Setting up a Plugin" on [Video.js' plugin documentation page][videojs-docs].

**Important: In addition to defining plugin configuration, you are required to define the
player's `techOrder` option, setting `'chromecast'` as the first Tech in the list.** Below
is an example of the minimum required configuration for the Chromecast plugin to function:

```js
var options;

options = {
   controls: true,
   techOrder: [ 'chromecast', 'html5' ], // You may have more Tech, such as Flash or HLS
   plugins: {
      chromecast: {}
   }
};

videojs(document.getElementById('myVideoElement'), options);
```

Please note that even if you choose not to use any of the configuration options, you must
either provide a `chromecast` entry in the `plugins` option for Video.js to initialize the
plugin for you:

```js
options = {
   plugins: {
      chromecast: {}
   }
};
```

or you must initialize the plugin manually:

```js
var player = videojs(document.getElementById('myVideoElement'));

player.chromecast(); // initializes the Chromecast plugin
```

#### Configuration options

##### Plugin configuration

   * **`plugins.chromecast.receiverAppID`** - the string ID of a custom [Chromecast
     receiver app][cast-receiver] to use. Defaults to the [default Media Receiver
     ID][def-cast-id].
   * **`plugins.chromecast.addButtonToControlBar`** - a `boolean` flag that tells the
     plugin whether or not it should automatically add the Chromecast button to the
     Video.js player's control bar component. Defaults to `true`.
   * **`plugins.chromecast.buttonPositionIndex`** - a zero-based number specifying the
     index of the Chromecast button among the control bar's child components (if
     `addButtonToControlBar` is set to `true`). By default the Chromecast Button is added
     as the last child of the control bar. A value less than 0 puts the button at the
     specified position from the end of the control bar. Note that it's likely not all
     child components of the control bar are visible.
   * **`plugins.chromecast.addCastLabelToButton`** (default: `false`) - by default, the
     Chromecast button component will display only an icon. Setting `addCastLabelToButton`
     to `true` will display a label titled `"Cast"` alongside the default icon.

##### Chromecast Tech configuration

   * **`chromecast.requestTitleFn`** - a function that this plugin calls when it needs a
     string that will be the title shown in the UI that is shown when a Chromecast session
     is active and connected. When the this plugin calls the `requestTitleFn`, it passes
     it the [current `source` object][player-source] and expects a string in return. If
     nothing is returned or if this option is not defined, no title will be shown.
   * **`chromecast.requestSubtitleFn`** - a function that this plugin calls when it needs
     a string that will be the sub-title shown in the UI that is shown when a Chromecast
     session is active and connected. When the this plugin calls the `requestSubtitleFn`,
     it passes it the [current `source` object][player-source] and expects a string in
     return. If nothing is returned or if this option is not defined, no sub-title will be
     shown.
   * **`chromecast.requestCustomDataFn`** - a function that this plugin calls when it
     needs an object that contains custom information necessary for a Chromecast receiver
     app when a session is active and connected. When the this plugin calls the
     `requestCustomDataFn`, it passes it the [current `source` object][player-source] and
     expects an object in return. If nothing is returned or if this option is not defined,
     no custom data will be sent. This option is intended to be used with a [custom
     receiver][custom-receiver] application to extend its default capabilities.
   * **`chromecast.modifyLoadRequestFn`** - a function that this plugin calls before doing
     the request to [load media][chromecast-load-media]. The function gets called with
     the [LoadRequest][chromecast-load-request] object as argument and expects it in
     return.

Here is an example configuration object that makes full use of all required and optional
configuration:

```js
var titles, subtitles, customData, options;

titles = {
   'https://example.com/videos/video-1.mp4': 'Example Title',
   'https://example.com/videos/video-2.mp4': 'Example Title2',
};

subtitles = {
   'https://example.com/videos/video-1.mp4': 'Subtitle',
   'https://example.com/videos/video-2.mp4': 'Subtitle2',
};

customData = {
   'https://example.com/videos/video-1.mp4': { 'customColor': '#0099ee' },
   'https://example.com/videos/video-2.mp4': { 'customColor': '#000080' },
};

options = {
   // Must specify the 'chromecast' Tech first
   techOrder: [ 'chromecast', 'html5' ], // Required
   // Configuration for the Chromecast Tech
   chromecast: {
      requestTitleFn: function(source) { // Not required
         return titles[source.url];
      },
      requestSubtitleFn: function(source) { // Not required
         return subtitles[source.url];
      },
      requestCustomDataFn: function(source) { // Not required
         return customData[source.url];
      },
      modifyLoadRequestFn: function (loadRequest) { // HLS support
         loadRequest.media.hlsSegmentFormat = 'fmp4';
         loadRequest.media.hlsVideoSegmentFormat = 'fmp4';
         return loadRequest;
      }
   },
   plugins: {
      chromecast: {
         receiverAppID: '1234' // Not required
         addButtonToControlBar: false, // Defaults to true
      },
   }
};
```

##### Localization

The `ChromecastButton` component has two translated strings: "Open Chromecast menu" and
"Cast".

   * The "Open Chromecast menu" string appears in both of the standard places for Button
     component accessibility text: inside the `.vjs-control-text` span and as the
     `<button>` element's `title` attribute.
   * The "Cast" string appears in an optional label within the Button component: inside
     the `.vjs-chromecast-button-label` span.

To localize the Chromecast button strings, follow the steps in the [Video.js Languages
tutorial][videojs-translation] to add `"Open Chromecast menu"` and `"Cast"` keys to the
map of translation strings.

### Using the NPM module

If you are using a module loader such as Browserify or Webpack, first install
`@silvermine/videojs-chromecast` using `npm install`. Then, use
`require('@silvermine/videojs-chromecast')` to require `@silvermine/videojs-chromecast`
into your project's source code. `require('@silvermine/videojs-chromecast')` returns a
function that you can use to register the plugin with Video.js by passing in a reference
to `videojs`:

```js
var videojs = require('video.js');

// Initialize the Chromecast plugin
require('@silvermine/videojs-chromecast')(videojs);
```

Then, follow the steps in the "Configuration" section above.

This plugin's source code uses ES6+ syntax and keywords, such as `class` and `static`. If
you need to support [browsers that do not support newer JavaScript
syntax](https://caniuse.com/es6), you will need to use a tool like
[Babel](https://babeljs.io/) to transpile and polyfill your code.

Alternatively, you can
`require('@silvermine/videojs-chromecast/dist/silvermine-videojs-chromecast.js')` to use a
JavaScript file that has already been polyfilled/transpiled down to ES5 compatibility.

### Using the CSS and images

If you are using SCSS in your project, you can simply reference the plugin's main SCSS
file in your project's SCSS:

```scss
@import "path/to/node_modules/@silvermine/videojs-chromecast/src/scss/videojs-chromecast";
```

Optionally, you can override the SCSS variables that contain the paths to the icon image
files:

   * **`$icon-chromecast--default`** - the path to the icon image that is displayed when
     the Chromecast button is in its normal, default state. Defaults to
     `"images/ic_cast_white_24dp.png"`.
   * **`$icon-chromecast--hover`** - the path to the icon image that is displayed when the
     user hovers over the Chromecast button when it is in its normal, default state.
     Defaults to `"images/ic_cast_white_24dp.png"`.
   * **`$icon-chromecast-casting`** - the path to the icon image that is displayed when
     the Chromecast button is in the "casting" state (when a Chromecast session is active
     and connected). Defaults to `"images/ic_cast_connected_white_24dp.png"`.
   * **`$icon-chromecast-casting--hover`** - the path to the icon image that is displayed
     when the user hovers over the Chromecast button when it is in the "casting" state
     (when a Chromecast session is active and connected). Defaults to
     `"images/ic_cast_connected_white_24dp.png"`.
   * **`$chromecast-icon-size`** - the width and height of the icon (the button and icon
     is a square). Defaults to `12px`.
   * **`$chromecast-title-font-size`** - the font size of the title on the screen that is
     shown while a Chromecast session is active and connected. Defaults to `22px`.
   * **`$chromecast-subtitle-font-size`** - the font size of the sub-title on the screen
     that is shown while a Chromecast session is active and connected. Defaults to `18px`.
   * **`$chromecast-poster-width`** - the width of the poster image on the screen that
     that is shown while a Chromecast session is active and connected. Defaults to
     `100px`.
   * **`$chromecast-poster-max-height`** - the maximum height of the poster image on the
     screen that is shown while a Chromecast session is active and connected. Defaults to
     `180px`.

#### Images

The plugin's images are located at `videojs-chromecast/src/images`. If you have
not overridden the icon image path variables in the SCSS, then copy the images from the
`src/images` folder to a folder that is accessible at `./images/`, relative to where the
plugin's CSS is located. If, for example, your CSS is located at
`https://example.com/plugins/silvermine-videojs-chromecast.css`, then the plugin's images
should be located at `https://example.com/plugins/images/`.

In addition, the `ic_cast_white_24dp.png` icon image that is used as the default icon for
all four button states ("default", "default + hover", "casting", "casting + hover"), the
`images` folder contains grey, black, and blue versions of the icons.

### Events

   * `chromecastConnected` - Triggers when Chromecast connected
   * `chromecastDisconnected` - Triggers when Chromecast disconnected
   * `chromecastDevicesAvailable` - Triggers on state change when Chromecast devices are
     available
   * `chromecastDevicesUnavailable` - Triggers on state change when Chromecast devices are
     unavailable
   * `chromecastRequested`: Triggers when the user has requested Chromecast playback using
     this plugin's Chromecast button

## How do I contribute?

We genuinely appreciate external contributions. See [our extensive
documentation][contributing] on how to contribute.

## License

This software is released under the MIT license. See [the license file](LICENSE) for more
details.

[videojs-docs]: http://docs.videojs.com/tutorial-plugins.html
[videojs-translation]: http://docs.videojs.com/tutorial-languages.html
[cast-receiver]: https://developers.google.com/cast/docs/receiver_apps
[def-cast-id]: https://developers.google.com/cast/docs/receiver_apps#default
[player-source]: http://docs.videojs.com/Player.html#currentSource
[custom-receiver]: https://developers.google.com/cast/docs/custom_receiver
[contributing]: https://github.com/silvermine/silvermine-info#contributing
[chromecast-load-media]: https://developers.google.com/cast/docs/reference/web_sender/cast.framework.CastSession#loadMedia
[chromecast-load-request]: https://developers.google.com/cast/docs/reference/web_sender/chrome.cast.media.LoadRequest