update text on main event thread

openlp/core/lib/renderer.py

@@ -79,6 +79,8 @@ class Renderer(object):
         self.force_page = False
         self.display = MainDisplay(None, self.image_manager, False, self)
         self.display.setup()
+        QtCore.QObject.connect(Receiver.get_receiver(),
+            QtCore.SIGNAL(u'renderer_update_text'), self.update_text)
         self._theme_dimensions = {}
         self._calculate_default()
         QtCore.QObject.connect(Receiver.get_receiver(),
@@ -223,7 +225,8 @@ class Renderer(object):
         self._set_theme(item_theme_name)
         self.item_theme_name = item_theme_name
 
-    def generate_preview(self, theme_data, force_page=False):
+    def generate_preview(self, theme_data, force_page=False,
+        same_thread=True):
         """
         Generate a preview of a theme.
 
@@ -258,11 +261,17 @@ class Renderer(object):
         if not self.force_page:
             self.display.buildHtml(serviceItem)
             raw_html = serviceItem.get_rendered_frame(0)
-            self.display.text(raw_html)
+            if same_thread:
+                Receiver.send_message(u'renderer_update_text', raw_html)
+            else:
+                self.update_text(raw_html)
             preview = self.display.preview()
             return preview
         self.force_page = False
 
+    def update_text(self, text):
+        self.display.text(text)
+com
     def format_slide(self, text, item):
         """
         Calculate how much text can fit on a slide.

openlp/core/ui/thememanager.py

@@ -741,7 +741,7 @@ class ThemeManager(QtGui.QWidget):
         """
         log.debug(u'generateImage \n%s ', theme_data)
         return self.mainwindow.renderer.generate_preview(
-            theme_data, forcePage)
+            theme_data, forcePage, False)
 
     def getPreviewImage(self, theme):
         """