Fix song flash

openlp/core/display/html/display.js

@@ -262,6 +262,7 @@ var Display = {
   _animationState: AnimationState.NoAnimation,
   _doTransitions: false,
   _doItemTransitions: false,
+  _skipNextTransition: false,
   _themeApplied: true,
   _revealConfig: {
     margin: 0.0,
@@ -365,7 +366,7 @@ var Display = {
     Display.applyTheme(new_slides, is_text);
     Display._slidesContainer.prepend(new_slides);
     var currentSlide = Reveal.getIndices();
-    if (Display._doItemTransitions && Display._slidesContainer.children.length >= 2) {
+    if (Display._doItemTransitions && Display._slidesContainer.children.length >= 2 && !Display._skipNextTransition) {
       // Set the slide one section ahead so we'll stay on the old slide after reinit
       Reveal.slide(1, currentSlide.v);
       Display.reinit();
@@ -375,6 +376,7 @@ var Display = {
       Reveal.slide(0, currentSlide.v);
       Reveal.sync();
       Display._removeLastSection();
+	  Display._skipNextTransition = false;
     }
   },
   /**
@@ -1121,6 +1123,18 @@ var Display = {
       }
     }
   },
+  /**
+   * Called whenever openlp wants to finish completely with the current text/image slides
+   * because a different window (eg presentation or vlc) is going to be displaying the next item
+   * and we don't want any flashbacks to the current slide contents
+   */
+  finishWithCurrentItem: function () {
+	Display.setTextSlide('');
+	var documentBody = $("body")[0];
+    documentBody.style.opacity = 1;
+	Display._skipNextTransition = true;
+	displayWatcher.pleaseRepaint();
+  },
   /**
    * Return the video types supported by the video tag
    */

openlp/core/display/window.py

@@ -51,6 +51,10 @@ class DisplayWatcher(QtCore.QObject):
     """
     initialised = QtCore.pyqtSignal(bool)
 
+    def __init__(self, parent):
+        super().__init__()
+        self._display_window = parent
+
     @QtCore.pyqtSlot(bool)
     def setInitialised(self, is_initialised):
         """
@@ -59,6 +63,13 @@ class DisplayWatcher(QtCore.QObject):
         log.info('Display is initialised: {init}'.format(init=is_initialised))
         self.initialised.emit(is_initialised)
 
+    @QtCore.pyqtSlot()
+    def pleaseRepaint(self):
+        """
+        Called from the js in the webengine view when it's requesting a repaint by Qt
+        """
+        self._display_window.webview.update()
+
 
 class DisplayWindow(QtWidgets.QWidget, RegistryProperties, LogMixin):
     """
@@ -451,6 +462,16 @@ class DisplayWindow(QtWidgets.QWidget, RegistryProperties, LogMixin):
         if self.is_display and self.hide_mode == HideMode.Screen:
             self.setVisible(False)
 
+    def finish_with_current_item(self):
+        """
+        This is called whenever the song/image display is followed by eg a presentation or video which
+        has its own display.
+        This function ensures that the current item won't flash momentarily when the webengineview
+        is displayed for a subsequent song or image.
+        """
+        self.run_javascript('Display.finishWithCurrentItem();', True)
+        self.webview.update()
+
     def set_scale(self, scale):
         """
         Set the HTML scale

openlp/core/ui/slidecontroller.py

@@ -945,23 +945,19 @@ class SlideController(QtWidgets.QWidget, LogMixin, RegistryProperties):
                 [self.service_item, self.is_live, self._current_hide_mode, slide_no])
         else:
             self._set_theme(self.service_item)
-        # Reset blanking if needed
-        if old_item and self.is_live and (old_item.is_capable(ItemCapabilities.ProvidesOwnDisplay) or
-                                          self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay)):
-            self._reset_blank(self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay))
         self.info_label.setText(self.service_item.title)
         self.slide_list = {}
-        if old_item:
+        # if the old item was text or images (ie doesn't provide its own display) and the new item provides its own
-            # Close the old item if it's not to be used by the new service item
+        # display then clear out the old item so that it doesn't flash momentarily when next showing text/image
-            if not self.service_item.is_media() and not self.service_item.requires_media():
+        # An item provides its own display if the capability ProvidesOwnDisplay is set or if it's a media item
-                self.on_media_close()
+        old_item_provides_own_display = old_item and (old_item.is_capable(ItemCapabilities.ProvidesOwnDisplay) or
-            if old_item.is_command() and not old_item.is_media():
+                                                      old_item.is_media())
-                Registry().execute('{name}_stop'.format(name=old_item.name.lower()), [old_item, self.is_live])
+        new_item_provides_own_display = (self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay) or
-            # if the old item was media which hid the main display then need to reset it if new service item uses it
+                                         self.service_item.is_media())
-            if self.is_live and self._current_hide_mode is None and old_item.is_media() and not \
+        if self.is_live and not old_item_provides_own_display and new_item_provides_own_display:
-                    old_item.requires_media() and not self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay):
+            for display in self.displays:
-                for display in self.displays:
+                display.finish_with_current_item()
-                    display.show_display()
+        # Prepare the new slides for text / image items
         row = 0
         width = self.main_window.control_splitter.sizes()[self.split]
         if self.service_item.is_text():
@@ -997,7 +993,23 @@ class SlideController(QtWidgets.QWidget, LogMixin, RegistryProperties):
                 row += 1
                 self.slide_list[str(row)] = row - 1
         self.preview_widget.replace_service_item(self.service_item, width, slide_no)
+        # Tidy up aspects associated with the old item
+        if old_item:
+            # Close the old item if it's not to be used by the new service item
+            if not self.service_item.is_media() and not self.service_item.requires_media():
+                self.on_media_close()
+            if old_item.is_command() and not old_item.is_media():
+                Registry().execute('{name}_stop'.format(name=old_item.name.lower()), [old_item, self.is_live])
+            # if the old item was media which hid the main display then need to reset it if new service item uses it
+            if self.is_live and self._current_hide_mode is None and old_item.is_media() and not \
+                    old_item.requires_media() and not self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay):
+                for display in self.displays:
+                    display.show_display()
         self.enable_tool_bar(self.service_item)
+        # Reset blanking if needed
+        if old_item and self.is_live and (old_item.is_capable(ItemCapabilities.ProvidesOwnDisplay) or
+                                          self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay)):
+            self._reset_blank(self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay))
         if self.service_item.is_media() or self.service_item.requires_media():
             self._set_theme(self.service_item)
             if self.service_item.is_command():

tests/openlp_core/display/test_window.py

@@ -622,3 +622,18 @@ def test_display_watcher_set_initialised():
 
         # THEN: initialised should have been emitted
         mocked_initialised.emit.assert_called_once_with(True)
+
+
+def test_display_watcher_please_repaint(display_window_env, mock_settings):
+    """
+    Test that the repaint is initiated
+    """
+    # GIVEN: A DisplayWindow instance with mocked out webview
+    display_window = DisplayWindow()
+    display_window.webview = MagicMock()
+
+    # WHEN: pleaseRepaint is called on the DisplayWatcher
+    display_window.display_watcher.pleaseRepaint()
+
+    # THEN: Qt update for the webview should have been triggered
+    assert display_window.webview.update.call_count == 1