Fix slow preview after fetching live image

openlp/core/ui/slidecontroller.py

@@ -206,7 +206,6 @@ class SlideController(QtWidgets.QWidget, LogMixin, RegistryProperties):
         self.panel = QtWidgets.QWidget(self.main_window.control_splitter)
         self.slide_list = {}
         self.slide_count = 0
-        self.slide_image = None
         self.controller_width = -1
         # Layout for holding panel
         self.panel_layout = QtWidgets.QVBoxLayout(self.panel)
@@ -1198,38 +1197,35 @@ class SlideController(QtWidgets.QWidget, LogMixin, RegistryProperties):
         if self.service_item and self.service_item.is_capable(ItemCapabilities.ProvidesOwnDisplay):
             if self.is_live:
                 # If live, grab screen-cap of main display now
-                QtCore.QTimer.singleShot(500, self.grab_maindisplay)
+                QtCore.QTimer.singleShot(500, self.display_maindisplay)
                 # but take another in a couple of seconds in case slide change is slow
-                QtCore.QTimer.singleShot(2500, self.grab_maindisplay)
+                QtCore.QTimer.singleShot(2500, self.display_maindisplay)
             else:
                 # If not live, use the slide's thumbnail/icon instead
                 image_path = Path(self.service_item.get_rendered_frame(self.selected_row))
-                # if self.service_item.is_capable(ItemCapabilities.HasThumbnails):
-                #     image = self.image_manager.get_image(image_path, ImageSource.CommandPlugins)
-                #     self.slide_image = QtGui.QPixmap.fromImage(image)
-                # else:
-                # self.slide_image = QtGui.QPixmap(image_path)
-                # self.slide_image.setDevicePixelRatio(self.main_window.devicePixelRatio())
-                # self.slide_preview.setPixmap(self.slide_image)
                 self.preview_display.set_single_image('#000', image_path)
         else:
             self.preview_display.go_to_slide(self.selected_row)
         self.slide_count += 1
 
+    def display_maindisplay(self):
+        """
+        Gets an image of the display screen and updates the preview frame.
+        """
+        display_image = self.grab_maindisplay()
+        base64_image = image_to_byte(display_image)
+        self.preview_display.set_single_image_data('#000', base64_image)
+
     def grab_maindisplay(self):
         """
-        Creates an image of the current screen and updates the preview frame.
+        Creates an image of the current screen.
         """
         win_id = QtWidgets.QApplication.desktop().winId()
         screen = QtWidgets.QApplication.primaryScreen()
         rect = ScreenList().current.display_geometry
         win_image = screen.grabWindow(win_id, rect.x(), rect.y(), rect.width(), rect.height())
         win_image.setDevicePixelRatio(self.preview_display.devicePixelRatio())
-        # self.slide_preview.setPixmap(win_image)
+        return win_image
-        self.slide_image = win_image
-        base64_image = image_to_byte(win_image)
-        self.preview_display.set_single_image_data('#000', base64_image)
-        return self.slide_image
 
     def on_slide_selected_next_action(self, checked):
         """

tests/functional/openlp_core/ui/test_slidecontroller.py

@@ -826,7 +826,7 @@ def test_update_preview_live(mocked_singleShot, mocked_image_manager, registry):
     slide_controller.screens.current = {'primary': ''}
     slide_controller.displays = [MagicMock()]
     slide_controller.display.preview.return_value = QtGui.QImage()
-    slide_controller.grab_maindisplay = MagicMock()
+    slide_controller.display_maindisplay = MagicMock()
     slide_controller.slide_preview = MagicMock()
     slide_controller.slide_count = 0
 
@@ -836,7 +836,7 @@ def test_update_preview_live(mocked_singleShot, mocked_image_manager, registry):
     # THEN: A screen_grab should have been called
     assert 0 == slide_controller.slide_preview.setPixmap.call_count, 'setPixmap should not be called'
     assert 0 == slide_controller.display.preview.call_count, 'display.preview() should not be called'
-    assert 2 == mocked_singleShot.call_count, 'Timer to grab_maindisplay should have been called 2 times'
+    assert 2 == mocked_singleShot.call_count, 'Timer to display_maindisplay should have been called 2 times'
     assert 0 == mocked_image_manager.get_image.call_count, 'image_manager not be called'
 
 
@@ -867,7 +867,7 @@ def test_update_preview_pres(mocked_singleShot, mocked_image_manager, registry):
     slide_controller.screens.current = {'primary': ''}
     slide_controller.displays = [MagicMock()]
     slide_controller.display.preview.return_value = QtGui.QImage()
-    slide_controller.grab_maindisplay = MagicMock()
+    slide_controller.display_maindisplay = MagicMock()
     slide_controller.slide_preview = MagicMock()
     slide_controller.slide_count = 0
     slide_controller.preview_display = MagicMock()
@@ -877,7 +877,7 @@ def test_update_preview_pres(mocked_singleShot, mocked_image_manager, registry):
 
     # THEN: setPixmap and the image_manager should have been called
     assert 1 == slide_controller.preview_display.set_single_image.call_count, 'set_single_image should be called'
-    assert 0 == mocked_singleShot.call_count, 'Timer to grab_maindisplay should not be called'
+    assert 0 == mocked_singleShot.call_count, 'Timer to display_maindisplay should not be called'
 
 
 @patch(u'openlp.core.ui.slidecontroller.SlideController.image_manager')
@@ -908,7 +908,7 @@ def test_update_preview_media(mocked_singleShot, mocked_image_manager, registry)
     slide_controller.screens.current = {'primary': ''}
     slide_controller.displays = [MagicMock()]
     slide_controller.display.preview.return_value = QtGui.QImage()
-    slide_controller.grab_maindisplay = MagicMock()
+    slide_controller.display_maindisplay = MagicMock()
     slide_controller.slide_preview = MagicMock()
     slide_controller.slide_count = 0
     slide_controller.preview_display = MagicMock()
@@ -918,7 +918,7 @@ def test_update_preview_media(mocked_singleShot, mocked_image_manager, registry)
 
     # THEN: setPixmap should have been called
     assert 1 == slide_controller.preview_display.set_single_image.call_count, 'set_single_image should be called'
-    assert 0 == mocked_singleShot.call_count, 'Timer to grab_maindisplay should not be called'
+    assert 0 == mocked_singleShot.call_count, 'Timer to display_maindisplay should not be called'
     assert 0 == mocked_image_manager.get_image.call_count, 'image_manager should not be called'
 
 
@@ -949,7 +949,7 @@ def test_update_preview_image(mocked_singleShot, mocked_image_manager, registry)
     slide_controller.screens = MagicMock()
     slide_controller.screens.current = {'primary': ''}
     slide_controller.displays = [MagicMock()]
-    slide_controller.grab_maindisplay = MagicMock()
+    slide_controller.display_maindisplay = MagicMock()
     slide_controller.slide_preview = MagicMock()
     slide_controller.slide_count = 0
     slide_controller.preview_display = MagicMock()
@@ -959,10 +959,31 @@ def test_update_preview_image(mocked_singleShot, mocked_image_manager, registry)
 
     # THEN: setPixmap and display.preview should have been called
     assert 1 == slide_controller.preview_display.go_to_slide.call_count, 'go_to_slide should be called'
-    assert 0 == mocked_singleShot.call_count, 'Timer to grab_maindisplay should not be called'
+    assert 0 == mocked_singleShot.call_count, 'Timer to display_maindisplay should not be called'
     assert 0 == mocked_image_manager.get_image.call_count, 'image_manager should not be called'
 
 
+@patch(u'openlp.core.ui.slidecontroller.image_to_byte')
+def test_display_maindisplay(mocked_image_to_byte, registry):
+    """
+    Test the display_maindisplay method
+    Here a string is substituted for what would be a screen capture of the display
+    The `image_to_byte` mocked funtion just adds " bytified" to the string
+    """
+    # GIVEN: A mocked slide controller, with mocked functions
+    slide_controller = SlideController(None)
+    slide_controller.grab_maindisplay = MagicMock(return_value='placeholder')
+    slide_controller.preview_display = MagicMock()
+    mocked_image_to_byte.side_effect = lambda x: '{} bytified'.format(x)
+
+    # WHEN: display_maindisplay is called
+    slide_controller.display_maindisplay()
+
+    # THEN: Should have grabbed the maindisplay and set to placeholder with a black background
+    slide_controller.grab_maindisplay.assert_called_once()
+    slide_controller.preview_display.set_single_image_data.assert_called_once_with('#000', 'placeholder bytified')
+
+
 def test_paint_event_text_fits():
     """
     Test the paintEvent method when text fits the label