Support on-the-fly tempo changes in Playback (#78)

melanchall · Feb 6, 2025 · 44559f4 · 44559f4
1 parent af3cb6b
commit 44559f4
Showing 1 changed file with 46 additions and 7 deletions.
diff --git a/DryWetMidi/Multimedia/Playback/Playback.DataManagement.cs b/DryWetMidi/Multimedia/Playback/Playback.DataManagement.cs
@@ -75,7 +75,6 @@ private void OnObservableTimedObjectsCollectionChanged(object sender, Observable
                     }
                 }
 
-                // TODO: optimize (see below for add, need to think about remove)
                 if (maxTime > _duration)
                 {
                     _duration = maxTime;
@@ -190,6 +189,10 @@ private void RemoveTimedObject(ITimedObject timedObject, long oldTime)
 
                 RemoveTrackedData(playbackEvent.Event, oldTime);
             }
+
+            TryRemoveSetTempoEvent(
+                timedEvent,
+                oldTime);
         }
 
         private void InitializePlaybackEvents(IEnumerable<ITimedObject> timedObjects, TempoMap tempoMap)
@@ -282,6 +285,29 @@ private NoteId GetNoteId(NoteEvent noteEvent)
             return new NoteId(noteEvent.Channel, noteEvent.NoteNumber);
         }
 
+        private void TryRemoveSetTempoEvent(
+            TimedEvent timedEvent,
+            long oldTime)
+        {
+            if (timedEvent == null)
+                return;
+
+            var setTempoEvent = timedEvent.Event as SetTempoEvent;
+            if (setTempoEvent == null)
+                return;
+
+            var valuesChanges = TempoMap.TempoLine.ToArray();
+            var valueChange = valuesChanges.FirstOrDefault(v => v.Time == oldTime);
+            if (valueChange == null)
+                return;
+
+
+            TempoMap.TempoLine.DeleteValues(oldTime, oldTime);
+
+            var oldTempo = valueChange.Value;
+            var newTempo = TempoMap.TempoLine.GetValueAtTime(oldTime);
+        }
+
         private void PrepareSetTempoEventAdding(
             TimedEvent timedEvent,
             out TimeSpan? nextTempoTime,
@@ -359,8 +385,26 @@ private bool TryAddSetTempoEvent(
                 ? _playbackEvents.GetLastNodeBelowThreshold(nextTempoTime.Value)
                 : null;
 
-            //
+            ScaleTimesAfterTempoChange(
+                oldTempo,
+                newTempo,
+                tempoChangeTime,
+                nextTempoTime,
+                firstNodeAfterTempoChange,
+                nodeBeforeNextTempo);
+
+            TempoMap.TempoLine.SetValue(timedEvent.Time, newTempo);
+            return true;
+        }
 
+        private void ScaleTimesAfterTempoChange(
+            Tempo oldTempo,
+            Tempo newTempo,
+            TimeSpan tempoChangeTime,
+            TimeSpan? nextTempoTime,
+            RedBlackTreeNode<TimeSpan, PlaybackEvent> firstNodeAfterTempoChange,
+            RedBlackTreeNode<TimeSpan, PlaybackEvent> nodeBeforeNextTempo)
+        {
             var scaleFactor = oldTempo.MicrosecondsPerQuarterNote / (double)newTempo.MicrosecondsPerQuarterNote;
 
             var shift = TimeSpan.Zero;
@@ -399,11 +443,6 @@ private bool TryAddSetTempoEvent(
 
                 _clock.SetCurrentTime(currentTime);
             }
-
-            //
-
-            TempoMap.TempoLine.SetValue(timedEvent.Time, newTempo);
-            return true;
         }
 
         private bool TryAddNoteEvent(