feat: Cast a website to Chromecast (via DashCast) (#102)

* Add Support for DashCast

* One commit solely honoring flake8

* it works but the code looks awful

* it's looking better

* the code looks good now

* oops

* minor changes to setup_cast

* minor comment, for clarity

* we now make good use of CastStatusListener

* _prep_control will again consider a webpage an inactive chromecast

* better way to use CastStatusListener

* updated readme and comments

* final changes?

* small changes

* DashCast does not need to fiddle with backdrop anymore

* Minor text fixes

* remove unused lines

* Big-ass comment about why this is here here.

README.rst

@@ -13,7 +13,7 @@ Cast All The Things
 
 Cast All The Things allows you to send videos from many, many online sources
 (YouTube, Vimeo, and a few hundred others) to your Chromecast. It also allows
-you to cast local files.
+you to cast local files or render websites.
 
 
 Installation
@@ -35,14 +35,27 @@ To use Cast All The Things, just specify a URL::
 
     catt cast "https://www.youtube.com/watch?v=dQw4w9WgXcQ"
 
-CATT supports any service that youtube-dl supports, which includes most online
+``catt`` supports any service that youtube-dl supports, which includes most online
 video hosting services.
 
-CATT can also cast local files (if they're in a format the Chromecast supports
+``catt`` can also cast local files (if they're in a format the Chromecast supports
 natively)::
 
     catt cast ./myvideo.mp4
 
+If you have subtitles and the name is similar to the name of the local file, ``catt`` will add them automatically.
+You can, of course, specify any other subtitle if you want. Although Chromecast only supports WEBVTT,
+TTML and Line 21 subtitles, ``catt`` conveniently converts SRTs to WEBVTT for you on the fly. Here is how to use it:
+
+    catt cast -s ./mysubtitle.srt /myvideo.mp4
+
+``catt`` can also tell your Chromecast to display any website::
+
+    catt cast_url https://en.wikipedia.org/wiki/Rickrolling
+
+Please note that the Chromecast has a slow CPU but a reasonably recent version of Google Chrome. The display
+resolution is 1280x720.
+
 You can also control your Chromecast through ``catt`` commands, for example with
 ``catt pause``. Try running ``catt --help`` to see the full list of commands.
 
@@ -78,11 +91,11 @@ edit ``catt.cfg``
 Contributing
 ------------
 
-If you want to contribute a feature to CATT, please open an issue (or comment on
+If you want to contribute a feature to ``catt``, please open an issue (or comment on
 an existing one) first, to make sure it's something that the maintainers are
 interested in. Afterwards, just clone the repository and hack away!
 
-To run CATT in development, you can use the following command::
+To run ``catt`` in development, you can use the following command::
 
     python -m catt.cli --help
 
@@ -99,3 +112,6 @@ Features
 
 * Casts videos to Chromecast.
 * From `many, many online sources <http://rg3.github.io/youtube-dl/supportedsites.html>`_.
+* Casts local files (videos, photos and music)
+* Casts any website to Chromecast
+

catt/cli.py

@@ -181,6 +181,15 @@ def process_subtitle(ctx, param, value):
     return value
 
 
+@cli.command(short_help="Cast any webpage to Chromecast")
+@click.argument("url")
+@click.pass_obj
+def cast_url(settings, url):
+    cst = setup_cast(settings["device"], prep="app", controller="dashcast")
+    click.echo("Casting URL %s on \"%s\"..." % (url, cst.cc_name))
+    cst.load_url(url)
+
+
 @cli.command(short_help="Send a video to a Chromecast for playing.")
 @click.argument("video_url", callback=process_url)
 @click.option("-s", "--subtitle",

catt/controllers.py

@@ -5,13 +5,18 @@
 
 import pychromecast
 from click import ClickException, echo
+from pychromecast.controllers.dashcast import APP_DASHCAST as DASHCAST_APP_ID
+from pychromecast.controllers.dashcast import DashCastController as PyChromecastDashCastController
 
 from .stream_info import StreamInfo
 from .util import warning
 from .youtube import YouTubeController
 
 
-APP_INFO = [{"app_name": "youtube", "app_id": "233637DE", "supported_device_types": ["cast"]}]
+APP_INFO = [
+    {"app_name": "youtube", "app_id": "233637DE", "supported_device_types": ["cast"]},
+    {"app_name": "dashcast", "app_id": DASHCAST_APP_ID, "supported_device_types": ["cast"]},
+]
 DEFAULT_APP = {"app_name": "default", "app_id": "CC1AD845"}
 BACKDROP_APP_ID = "E8C28D3C"
 
@@ -110,6 +115,10 @@ def setup_cast(device_name, video_url=None, prep=None, controller=None):
 
     if app["app_name"] == "youtube":
         controller = YoutubeCastController(cast, app["app_name"], app["app_id"], prep=prep)
+    elif app["app_name"] == "dashcast":
+        if cast.cast_type not in app["supported_device_types"]:
+            raise CattCastError("The %s app is not available for this device." % app["app_name"].capitalize())
+        controller = DashCastController(cast, app["app_name"], app["app_id"], prep=prep)
     else:
         controller = DefaultCastController(cast, app["app_name"], app["app_id"], prep=prep)
     return (controller, stream) if stream else controller
@@ -223,15 +232,32 @@ class CastStatusListener:
     def __init__(self, app_id, active_app_id):
         self.app_id = app_id
         self.app_ready = threading.Event()
-        if app_id == active_app_id:
+        if app_id == active_app_id and app_id != DASHCAST_APP_ID:
             self.app_ready.set()
 
     def new_cast_status(self, status):
-        if status.app_id == self.app_id:
+        if self._is_app_ready(status):
             self.app_ready.set()
         else:
             self.app_ready.clear()
 
+    def _is_app_ready(self, status):
+        if status.app_id == self.app_id == DASHCAST_APP_ID:
+            # DashCast is an exception and therefore needs special treatment.
+            # Whenever it's loaded, it's initial status is "Application is starting",
+            # as shown here: https://github.com/stestagg/dashcast/blob/master/receiver.html#L163
+            # While in that status, it's still not ready to start receiving nor loading URLs
+            # Therefore we must wait until its status change to "Application ready"
+            # https://github.com/stestagg/dashcast/blob/master/receiver.html#L143
+            #
+            # If one does not wait for the status to become "Application ready",
+            # casting the URL will trigger a race condition as the URL may arrive before the
+            # "Application ready" status. In this case, casting will not work.
+            # One simple way to confirm changes is to uncomment the line below
+            # print(status.status_text)
+            return status.status_text == "Application ready"
+        return status.app_id == self.app_id
+
 
 class MediaStatusListener:
     def __init__(self, state):
@@ -325,15 +351,13 @@ def _is_seekable(self):
                         status.stream_type == "BUFFERED") else False
 
     def _prep_app(self):
-        """Make shure desired chromecast app is running."""
-
+        """Make sure desired chromecast app is running."""
         if not self._cast_listener.app_ready.is_set():
             self._cast.start_app(self._cast_listener.app_id)
             self._cast_listener.app_ready.wait()
 
     def _prep_control(self):
-        """Make shure chromecast is in an active state."""
-
+        """Make sure chromecast is in an active state."""
         if self._cast.app_id == BACKDROP_APP_ID or not self._cast.app_id:
             raise CattCastError("Chromecast is inactive.")
         self._cast.media_controller.block_until_active(1.0)
@@ -447,6 +471,22 @@ def restore(self, data):
                             title=data["title"], thumb=data["thumb"])
 
 
+class DashCastController(CastController):
+    def __init__(self, cast, name, app_id, prep=None):
+        self._controller = PyChromecastDashCastController()
+        super(DashCastController, self).__init__(cast, name, app_id, prep=prep)
+
+    def load_url(self, url, **kwargs):
+        self._controller.load_url(url, force=True)
+
+    def _prep_app(self):
+        """Make sure desired chromecast app is running."""
+        # we must force the launch of the DashCast app because it, by design,
+        # becomes unresponsive after a website is loaded
+        self._cast.socket_client.receiver_controller.launch_app(self._cast_listener.app_id, force_launch=True)
+        self._cast_listener.app_ready.wait()
+
+
 class YoutubeCastController(CastController):
     def __init__(self, cast, name, app_id, prep=None):
         self._controller = YouTubeController()