move live view to websockets

openlp/plugins/remotes/html/js/main.js

@@ -28,18 +28,23 @@ window.OpenLP = {
     );
   },
   pollServer: function () {
-    $.getJSON(
-      "/main/poll",
-      function (data, status) {
-        if (OpenLP.slideCount != data.results.slide_count) {
-          OpenLP.slideCount = data.results.slide_count;
+    if ("WebSocket" in window) {
+        // Let us open a web socket
+        var ws = new WebSocket('ws://' + location.hostname + ':4318/main_poll');
+        ws.binaryType = 'arraybuffer';
+        ws.onmessage = function (evt) {
+            var msg = JSON.parse(String.fromCharCode.apply(null, new Uint8Array(evt.data)));
+            if (OpenLP.slideCount != msg.results.slide_count) {
+              OpenLP.slideCount = msg.results.slide_count;
               OpenLP.loadSlide();
             }
         }
-    );
+    } else {
+        // The browser doesn't support WebSocket
+        alert("WebSocket NOT supported by your Browser!");
     }      
-}
+  }
+};
 $.ajaxSetup({ cache: false });
-setInterval("OpenLP.pollServer();", 500);
 OpenLP.pollServer();
 

openlp/plugins/remotes/lib/httpserver.py

@@ -198,6 +198,7 @@ class OpenLPServer(RegistryProperties, OpenLPMixin):
         """
         log.debug("web socket handler registered with client")
         previous_poll = None
+        previous_main_poll = None
         if path == '/poll':
             while True:
                 current_poll = OpenLPPoll().poll()
@@ -205,6 +206,13 @@ class OpenLPServer(RegistryProperties, OpenLPMixin):
                     await request.send(current_poll)
                     previous_poll = current_poll
                 await asyncio.sleep(0.2)
+        elif path == '/main_poll':
+            while True:
+                main_poll = OpenLPPoll().main_poll()
+                if main_poll != previous_main_poll:
+                    await request.send(main_poll)
+                    previous_main_poll = main_poll
+                await asyncio.sleep(0.2)
 
     def stop_server(self):
         """

openlp/plugins/remotes/lib/poll.py

@@ -50,3 +50,12 @@ class OpenLPPoll(RegistryProperties):
             'isAuthorised': False
         }
         return json.dumps({'results': result}).encode()
+
+    def main_poll(self):
+        """
+        Poll OpenLP to determine the current slide count.
+        """
+        result = {
+            'slide_count': self.live_controller.slide_count
+        }
+        return json.dumps({'results': result}).encode()

scripts/check_dependencies.py

@@ -94,6 +94,7 @@ MODULES = [
     'mako',
     'uno',
     'websockets',
+    'asyncio',
     'six'
 ]