Add interface to force-load next source

billboard/app.py

@@ -4,7 +4,7 @@
 import signal
 import tempfile
 import logging
-
+import queue
 
 from PyQt4.QtGui import QApplication
 
@@ -47,11 +47,14 @@ def main():
         logging.debug('Creating {}'.format(workdir))
         os.makedirs(workdir)
 
-    server = Server(workdir, args.port)
+    # We use a queue to communicate between threads
+    q = queue.Queue()
+
+    server = Server(workdir, args.port, q)
     display = BillboardDisplay(workdir=workdir)
     sources = [RedditSource()]
 
-    billboard = Billboard(display, sources, args.period)
+    billboard = Billboard(display, sources, args.period, q)
 
     billboard.start()
     display.showFullScreen()

billboard/billboard.py

@@ -1,15 +1,17 @@
 import time
 from threading import Thread
 from itertools import cycle
+from queue import Empty
 
 
 class Billboard(Thread):
 
-    def __init__(self, display, sources, period):
+    def __init__(self, display, sources, period, q):
         super(Billboard, self).__init__()
         self.display = display
         self.sources = sources
         self.period = period
+        self.q = q
         self.daemon = True
 
     def run(self):
@@ -21,5 +23,13 @@ def run(self):
                 self.display.update_image(image)
             if text is not None:
                 self.display.display_text(text)
+            # HACK: We sleep for a moment to make sure that this
+            # display has updated before we take the screenshot. This
+            # is not an issue on slower devices, but can occur on
+            # faster machines.
+            time.sleep(1)
             self.display.update_current()
-            time.sleep(self.period)
+            try:
+                self.q.get(timeout=self.period)
+            except Empty:
+                pass

billboard/server.py

@@ -1,16 +1,17 @@
 import os
 import threading
 
-from flask import Flask,request, send_from_directory
+from flask import Flask, request, send_from_directory
 
 
 class Server(threading.Thread):
 
-    def __init__(self, workdir, port):
+    def __init__(self, workdir, port, q):
         super(Server, self).__init__()
         self.daemon = True
         self.workdir = workdir
         self.port = port
+        self.q = q
 
     def run(self):
         app = Flask('billboard')
@@ -26,6 +27,14 @@ def current():
             response.headers['Pragma'] = 'no-cache'
             return  response
 
+        @app.route('/next')
+        def next():
+            # We just put SOMETHING into the queue. It doesn't matter
+            # what it is as we discard it anyhow.
+            self.q.put(None)
+            return  "Loading the next image!"
+
+
         app.run(host='0.0.0.0', port=self.port)