Use action-delay QTimers right

If a timer is simply meant to introduce a delay before some action, it
can be set .setSingleShot(True). Then:
  * start() will cause it to run for interval() ms, trigger once,
    and then auto-reset to stop()ped.
  * Calls to .start() WHILE it's running will reset the timeout to
    interval() ms. (Technically it's stopped-and-restarted.)
  * It will only ever run its timeout() callback ONCE per start()
    from a stopped state, even if it's reset multiple times.
  * It never needs to be explicitly stop()ped except to cancel it.

Author: ferdnyc

src/windows/export.py

@@ -34,9 +34,9 @@
 
 # Try to get the security-patched XML functions from defusedxml
 try:
-  from defusedxml import minidom as xml
+    from defusedxml import minidom as xml
 except ImportError:
-  from xml.dom import minidom as xml
+    from xml.dom import minidom as xml
 
 from xml.parsers.expat import ExpatError
 
@@ -101,8 +101,8 @@ def __init__(self):
         self.delayed_fps_timer = None
         self.delayed_fps_timer = QTimer()
         self.delayed_fps_timer.setInterval(200)
+        self.delayed_fps_timer.setSingleShot(True)
         self.delayed_fps_timer.timeout.connect(self.delayed_fps_callback)
-        self.delayed_fps_timer.stop()
 
         # Pause playback (to prevent crash since we are fixing to change the timeline's max size)
         get_app().window.actionPlay_trigger(None, force="pause")
@@ -288,10 +288,8 @@ def __init__(self):
         self.updateFrameRate()
 
     def delayed_fps_callback(self):
-        """Callback for fps/profile changed event timer (to delay the timeline mapping so we don't spam libopenshot)"""
-        # Stop timer
-        self.delayed_fps_timer.stop()
-
+        """Callback for fps/profile changed event timer
+        (to delay the timeline mapping so we don't spam libopenshot)"""
         # Calculate fps
         fps_double = self.timeline.info.fps.ToDouble()
 
@@ -355,7 +353,8 @@ def updateFrameRate(self):
         self.timeline.info.channels = self.txtChannels.value()
         self.timeline.info.channel_layout = self.cboChannelLayout.currentData()
 
-        # Send changes to libopenshot (apply mappings to all framemappers)... after a small delay
+        # Send changes to libopenshot (apply mappings to all framemappers)
+        # Start or restart timer to process changes after a small delay
         self.delayed_fps_timer.start()
 
         # Determine max frame (based on clips)

src/windows/main_window.py

@@ -2534,11 +2534,10 @@ def hideEvent(self, event):
     def show_property_timeout(self):
         """Callback for show property timer"""
 
-        # Stop timer
-        self.show_property_timer.stop()
-
         # Emit load properties signal
-        self.propertyTableView.loadProperties.emit(self.show_property_id, self.show_property_type)
+        self.propertyTableView.loadProperties.emit(
+            self.show_property_id,
+            self.show_property_type)
 
     def InitKeyboardShortcuts(self):
         """Initialize all keyboard shortcuts from the settings file"""
@@ -2754,8 +2753,8 @@ def __init__(self, mode=None):
         self.show_property_type = None
         self.show_property_timer = QTimer()
         self.show_property_timer.setInterval(100)
+        self.show_property_timer.setSingleShot(True)
         self.show_property_timer.timeout.connect(self.show_property_timeout)
-        self.show_property_timer.stop()
 
         # Setup video preview QWidget
         self.videoPreview = VideoWidget()

src/windows/models/properties_model.py

@@ -549,9 +549,6 @@ def update_model(self, filter=""):
         app = get_app()
         _ = app._tr
 
-        # Stop QTimer
-        self.update_timer.stop()
-
         # Check for a selected clip
         if self.selected and self.selected[0]:
             c, item_type = self.selected[0]
@@ -824,8 +821,8 @@ def __init__(self, parent, *args):
         # to update the property model hundreds of times)
         self.update_timer = QTimer()
         self.update_timer.setInterval(100)
+        self.update_timer.setSingleShot(True)
         self.update_timer.timeout.connect(self.update_item_timeout)
-        self.update_timer.stop()
         self.next_item_id = None
         self.next_item_type = None
 

src/windows/video_widget.py

@@ -717,9 +717,6 @@ def resizeEvent(self, event):
 
     def delayed_resize_callback(self):
         """Callback for resize event timer (to delay the resize event, and prevent lots of similar resize events)"""
-        # Stop timer
-        self.delayed_resize_timer.stop()
-
         # Ensure width & height are divisible by 2 (round decimals).
         # Trying to find the closest even number to the requested aspect ratio
         # so that both width and height are divisible by 2. This is to prevent some
@@ -838,8 +835,8 @@ def __init__(self, *args):
         self.delayed_size = None
         self.delayed_resize_timer = QTimer()
         self.delayed_resize_timer.setInterval(200)
+        self.delayed_resize_timer.setSingleShot(True)
         self.delayed_resize_timer.timeout.connect(self.delayed_resize_callback)
-        self.delayed_resize_timer.stop()
 
         # Connect to signals
         self.win.TransformSignal.connect(self.transformTriggered)

src/windows/views/timeline_webview.py

@@ -1936,7 +1936,7 @@ def Slice_Triggered(self, action, clip_ids, trans_ids, playhead_position=0):
             # Save changes
             self.update_clip_data(clip.data, only_basic_props=False, ignore_reader=True)
 
-        # Start timer to redraw audio waveforms
+        # Start or restart timer to redraw audio waveforms
         self.redraw_audio_timer.start()
 
         # Loop through each transition (using the list of ids)
@@ -2737,7 +2737,7 @@ def update_zoom(self, newValue):
         cmd = JS_SCOPE_SELECTOR + ".setScale(" + str(newScale) + "," + str(cursor_x) + ");"
         self.eval_js(cmd)
 
-        # Start timer to redraw audio
+        # Start or restart timer to redraw audio
         self.redraw_audio_timer.start()
 
         # Only update scale if different
@@ -3046,9 +3046,6 @@ def redraw_audio_onTimeout(self):
         """Timer is ready to redraw audio (if any)"""
         log.info('redraw_audio_onTimeout')
 
-        # Stop timer
-        self.redraw_audio_timer.stop()
-
         # Pass to javascript timeline (and render)
         cmd = JS_SCOPE_SELECTOR + ".reDrawAllAudioData();"
         self.page().mainFrame().evaluateJavaScript(cmd)
@@ -3138,6 +3135,7 @@ def __init__(self, window):
         # Delayed zoom audio redraw
         self.redraw_audio_timer = QTimer(self)
         self.redraw_audio_timer.setInterval(300)
+        self.redraw_audio_timer.setSingleShot(True)
         self.redraw_audio_timer.timeout.connect(self.redraw_audio_onTimeout)
 
         # QTimer for cache rendering