Implement workaround for unblanking bug in powerpoint 2010

openlp/plugins/presentations/lib/messagelistener.py

@@ -244,7 +244,8 @@ class Controller(object):
         """
         log.debug('Live = %s, stop' % self.is_live)
         # Save the current slide number to be able to return to this slide if the presentation is activated again.
-        self.doc.slidenumber = self.doc.get_slide_number()
+        if self.doc.is_active():
+            self.doc.slidenumber = self.doc.get_slide_number()
         self.hide_mode = HideMode.Screen
         if not self.doc:
             return

openlp/plugins/presentations/lib/powerpointcontroller.py

@@ -37,6 +37,8 @@ if is_win():
     import winreg
     import win32ui
     import pywintypes
+    import win32con
+    import win32api
 
 from openlp.core.lib import ScreenList
 from openlp.core.lib.ui import UiStrings, critical_error_message_box, translate
@@ -225,10 +227,24 @@ class PowerpointDocument(PresentationDocument):
         """
         log.debug('unblank_screen')
         try:
-            self.presentation.SlideShowSettings.Run()
-            # ppSlideShowRunning = 1
-            self.presentation.SlideShowWindow.View.State = 1
-            self.presentation.SlideShowWindow.Activate()
+            # Powerpoint 2010 (14.0) has a bug that prevents unblanking from working, 
+            # so we have to works around it by sending a keystroke to Powerpoint.
+            # The keystroke 'U' should not have any bindings in Powerpoint so we use that
+            if float(self.presentation.Application.Version) == 14.0:
+                loops = 0
+                while self.presentation.SlideShowWindow.View.State == 3:
+                    if loops >= 10:
+                        log.warning('Tried to unblank 10 times, break to avoid hang, leaving presentation blanked.')
+                        break
+                    log.debug('Unblanking by sending "U"')
+                    self.presentation.SlideShowWindow.Activate()
+                    win32api.keybd_event(ord('U'), 0, 0, 0)
+                    time.sleep(0.01)
+                    win32api.keybd_event(ord('U'), 0, win32con.KEYEVENTF_KEYUP, 0)
+                    loops += 1
+            else:
+                # ppSlideShowRunning = 1
+                self.presentation.SlideShowWindow.View.State = 1
         except (AttributeError, pywintypes.com_error) as e:
             log.exception('Caught exception while in unblank_screen')
             log.exception(e)