guard against a rare crash that happens when a qt widget tries to access a just deleted track, because the widget itself got deleted which triggered an out-of-focus-send-to-engine event

engine/api.py

@@ -475,6 +475,7 @@ def set_measuresPerGroup(value):
 def changeTrackName(trackId, name):
     """The template gurantees a unique, sanitized name across tracks and groups"""
     track = session.data.trackById(trackId)
+    if not track: return
     if not name.lower() in (gr.lower() for gr in getGroups()):
         session.history.register(lambda trId=trackId, v=track.sequencerInterface.name: changeTrackName(trId,v), descriptionString="Track Name")
         track.sequencerInterface.name = name #sanitizes on its own. Checks for duplicate tracks but not groups
@@ -483,6 +484,7 @@ def changeTrackName(trackId, name):
 def changeTrackColor(trackId, colorInHex):
     """Expects "#rrggbb"""
     track = session.data.trackById(trackId)
+    if not track: return
     assert len(colorInHex) == 7, colorInHex
     session.history.register(lambda trId=trackId, v=track.color: changeTrackColor(trId,v), descriptionString="Track Color")
     track.color = colorInHex
@@ -495,6 +497,7 @@ def changeTrackMidiChannel(trackId, newChannel:int):
         logger.warning(f"Midi Channel must be between 1-16 for this function, was: {newChannel}. Doing nothing.")
         return
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.midiChannel: changeTrackMidiChannel(trId,v), descriptionString="Track Midi Channel")
     track.midiChannel = newChannel-1
     track.pattern.buildExportCache()
@@ -517,6 +520,7 @@ def createSiblingTrack(trackId): #aka clone track
     The jack midi out will be independent after creation, but connected to the same instrument
     (if any)"""
     track = session.data.trackById(trackId)
+    if not track: return
     assert type(track.pattern.scale) == tuple
     newTrack = session.data.addTrack(name=track.sequencerInterface.name, scale=track.pattern.scale, color=track.color, simpleNoteNames=track.pattern.simpleNoteNames) #track name increments itself from "Track A" to "Track B" or "Track 1" -> "Track 2"
     newTrack.pattern.averageVelocity = track.pattern.averageVelocity
@@ -551,6 +555,7 @@ def _reinsertDeletedTrack(track, trackIndex):
 
 def deleteTrack(trackId):
     track = session.data.trackById(trackId)
+    if not track: return
     oldIndex = session.data.tracks.index(track)
     with session.history.sequence("Delete Track"):
         setTrackGroup(trackId, "") #has it's own undo
@@ -562,8 +567,6 @@ def deleteTrack(trackId):
         else:
             session.history.register(lambda tr=deletedTrack, pos=oldIndex: _reinsertDeletedTrack(tr, pos), descriptionString="Delete Track")
 
-    print (session.data.groups)
-
     updatePlayback()
     callbacks._numberOfTracksChanged()
 
@@ -574,6 +577,7 @@ def moveTrack(trackId, newIndex):
     in session.data.tracks , so that jack metadata port order works, groups or not.
     """
     track = session.data.trackById(trackId)
+    if not track: return
     oldIndex = session.data.tracks.index(track)
     if not oldIndex == newIndex:
         session.history.register(lambda tr=trackId, pos=oldIndex: moveTrack(trackId, pos), descriptionString="Move Track")
@@ -587,6 +591,7 @@ def setTrackPatternLengthMultiplicator(trackId, newMultiplicator:int):
         return #Invalid input
 
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda tr=trackId, v=track.patternLengthMultiplicator: setTrackPatternLengthMultiplicator(trackId, v), descriptionString="Pattern Multiplier")
     track.patternLengthMultiplicator = newMultiplicator
     track.pattern.buildExportCache()
@@ -610,6 +615,7 @@ def setTrackGroup(trackId, groupName:str):
     """A not yet existing groupName will create that.
     Set to empty string to create a standalone track"""
     track = session.data.trackById(trackId)
+    if not track: return
     groupName = ''.join(ch for ch in groupName if ch.isalnum()) #sanitize
     groupName = " ".join(groupName.split()) #remove double spaces
     if not track.group == groupName:
@@ -675,6 +681,7 @@ def _setTrackStructure(trackId, structure, undoMessage):
     """For undo. Used by all functions as entry point, then calls itself for undo/redo.
     structure is a set of integers which we can copy with .copy()"""
     track = session.data.trackById(trackId)
+    if not track: return
 
     session.history.register(lambda tr=trackId, v=track.structure.copy(), msg=undoMessage: _setTrackStructure(trackId, v, msg), descriptionString=undoMessage)
 
@@ -687,6 +694,7 @@ def _setTrackStructure(trackId, structure, undoMessage):
 def setSwitches(trackId, setOfPositions, newBool):
     """Used in the GUI to select multiple switches in a row by dragging the mouse"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda tr=trackId, v=track.structure.copy(): _setTrackStructure(trackId, v, "Set Measures"), descriptionString="Set Measures")
     if newBool:
         track.structure = track.structure.union(setOfPositions) #merge: add setOfPositions to the existing one
@@ -698,6 +706,7 @@ def setSwitches(trackId, setOfPositions, newBool):
 
 def setSwitch(trackId, position, newBool):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Set Measures"), descriptionString="Set Measures")
     if newBool:
         if position in track.structure: return
@@ -712,6 +721,7 @@ def setSwitch(trackId, position, newBool):
 
 def trackInvertSwitches(trackId):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Invert Measures"), descriptionString="Invert Measures")
     """
     if track.structure:
@@ -728,6 +738,7 @@ def trackInvertSwitches(trackId):
 
 def trackOffAllSwitches(trackId):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Track Measures Off"), descriptionString="Track Measures Off")
     track.structure = set()
     track.buildTrack()
@@ -736,6 +747,7 @@ def trackOffAllSwitches(trackId):
 
 def trackOnAllSwitches(trackId):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Track Measures On"), descriptionString="Track Measures On")
     track.structure = set(i for i in range(session.data.numberOfMeasures))
     track.buildTrack()
@@ -773,6 +785,7 @@ def _setSwitchesScaleTranspose(trackId, whichPatternsAreScaleTransposed):
     """For undo. Used by all functions as entry point, then calls itself for undo/redo.
     whichPatternsAreScaleTransposed is a dicts of int:int which we can copy with .copy()"""
     track = session.data.trackById(trackId)
+    if not track: return
 
     session.history.register(lambda tr=trackId, v=track.whichPatternsAreScaleTransposed.copy(): _setSwitchesScaleTranspose(trackId, v), descriptionString="Set Modal Shift")
 
@@ -785,6 +798,7 @@ def _setSwitchesScaleTranspose(trackId, whichPatternsAreScaleTransposed):
 def setSwitchScaleTranspose(trackId, position, transpose):
     """Scale transposition is flipped. lower value means higher pitch"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda tr=trackId, v=track.whichPatternsAreScaleTransposed.copy(): _setSwitchesScaleTranspose(trackId, v), descriptionString="Set Modal Shift")
     track.whichPatternsAreScaleTransposed[position] = transpose
     track.buildTrack()
@@ -797,6 +811,7 @@ def _setSwitchHalftoneTranspose(trackId, whichPatternsAreHalftoneTransposed):
     """For undo. Used by all functions as entry point, then calls itself for undo/redo.
     whichPatternsAreScaleTransposed is a dicts of int:int which we can copy with .copy()"""
     track = session.data.trackById(trackId)
+    if not track: return
 
     session.history.register(lambda tr=trackId, v=track.whichPatternsAreHalftoneTransposed.copy(): _setSwitchHalftoneTranspose(trackId, v), descriptionString="Set Half Tone Shift")
 
@@ -808,6 +823,7 @@ def _setSwitchHalftoneTranspose(trackId, whichPatternsAreHalftoneTransposed):
 def setSwitchHalftoneTranspose(trackId, position, transpose):
     """Halftone transposition is not flipped. Higher value means higher pitch"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda tr=trackId, v=track.whichPatternsAreHalftoneTransposed.copy(): _setSwitchHalftoneTranspose(trackId, v), descriptionString="Set Half Tone Shift")
     track.whichPatternsAreHalftoneTransposed[position] = transpose
     track.buildTrack()
@@ -1015,6 +1031,7 @@ def setPattern(trackId, patternList, undoMessage):
     It is rarely used directly by the GUI, if at all. Normal changes are atomic.
     """
     track = session.data.trackById(trackId)
+    if not track: return
 
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(), msg=undoMessage: setPattern(trId, v, msg), descriptionString=undoMessage)
 
@@ -1037,6 +1054,7 @@ def setStep(trackId, stepExportDict):
     This is also for velocity!
     """
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Change Step"), descriptionString="Change Step")
     oldNote = track.pattern.stepByIndexAndPitch(index=stepExportDict["index"], pitch=stepExportDict["pitch"])
     if oldNote:  #modify existing note
@@ -1054,6 +1072,7 @@ def setStep(trackId, stepExportDict):
 def removeStep(trackId, index, pitch):
     """Reverse of setStep"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Remove Step"), descriptionString="Remove Step")
     oldNote = track.pattern.stepByIndexAndPitch(index, pitch)
     track.pattern.data.remove(oldNote)
@@ -1066,6 +1085,7 @@ def setScale(trackId, scale, callback = True):
     """Expects a scale list or tuple from lowest index to highest.
     Actual pitches don't matter."""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.scale[:]: setScale(trId, v, callback=True), descriptionString="Set Scale")
     track.pattern.scale = scale #tuple, or list if oversight in json loading :)
     track.pattern.buildExportCache()
@@ -1078,12 +1098,14 @@ def setSimpleNoteNames(trackId, simpleNoteNames):
     """note names is a list of strings with length 128. One name for each midi note.
     It is saved to file"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.simpleNoteNames[:]: setSimpleNoteNames(trId, v), descriptionString="Note Names")
     track.pattern.simpleNoteNames = simpleNoteNames #list of strings
     callbacks._trackMetaDataChanged(track)
 
 def transposeHalftoneSteps(trackId, steps):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.scale[:]: setScale(trId, v, callback=True), descriptionString="Transpose Scale")
     track.pattern.scale = [midipitch+steps for midipitch in track.pattern.scale]
     track.pattern.buildExportCache()
@@ -1093,6 +1115,7 @@ def transposeHalftoneSteps(trackId, steps):
 
 def patternInvertSteps(trackId):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Invert Steps"), descriptionString="Invert Steps")
     track.pattern.invert()
     track.pattern.buildExportCache()
@@ -1102,6 +1125,7 @@ def patternInvertSteps(trackId):
 
 def patternOnAllSteps(trackId):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "All Steps On"), descriptionString="All Steps On")
     track.pattern.fill()
     track.pattern.buildExportCache()
@@ -1111,6 +1135,7 @@ def patternOnAllSteps(trackId):
 
 def patternOffAllSteps(trackId):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "All Steps Off"), descriptionString="All Steps Off")
     track.pattern.empty()
     track.pattern.buildExportCache()
@@ -1121,6 +1146,7 @@ def patternOffAllSteps(trackId):
 def patternInvertRow(trackId, pitchindex):
     """Pitchindex is the row"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Invert Row"), descriptionString="Invert Row")
     track.pattern.invertRow(pitchindex)
     track.pattern.buildExportCache()
@@ -1132,6 +1158,7 @@ def patternClearRow(trackId, pitchindex):
     """Pitchindex is the row.
     Index is the column"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Clear Row"), descriptionString="Clear Row")
     track.pattern.clearRow(pitchindex)
     track.pattern.buildExportCache()
@@ -1143,6 +1170,7 @@ def patternRowRepeatFromStep(trackId, pitchindex, index):
     """Pitchindex is the row.
     Index is the column"""
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Fill Row with Repeat"), descriptionString="Fill Row with Repeat")
     track.pattern.repeatFromStep(pitchindex, index)
     track.pattern.buildExportCache()
@@ -1152,6 +1180,7 @@ def patternRowRepeatFromStep(trackId, pitchindex, index):
 
 def patternRowChangeVelocity(trackId, pitchindex, delta):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Change Row Velocity"), descriptionString="Change Row Velocity")
     for note in track.pattern.getRow(pitchindex):
         new = note["velocity"] + delta
@@ -1204,6 +1233,7 @@ def setScaleToKeyword(trackId, keyword):
     This function is called not often and does not need to be performant.
     """
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.scale[:]: setScale(trId, v, callback=True), descriptionString="Set Scale")
 
     rememberRootNote = track.pattern.scale[-1] #The last note has a special role by convention. No matter if this is the lowest midi-pitch or not. Most of the time it is the lowest though.
@@ -1248,6 +1278,7 @@ def setScaleToKeyword(trackId, keyword):
 
 def changePatternVelocity(trackId, steps):
     track = session.data.trackById(trackId)
+    if not track: return
     session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Change Pattern Velocity"), descriptionString="Change Pattern Velocity")
     for note in track.pattern.data:
         new = note["velocity"] + steps
@@ -1272,6 +1303,7 @@ def resizePatternWithoutScale(trackId, steps):
         return
 
     track = session.data.trackById(trackId)
+    if not track: return
 
     #We could use setScale for undo. But this requires a different set of callbacks. We use our own function, eventhough some of the calculations are not needed for undo.
 
@@ -1305,11 +1337,13 @@ def resizePatternWithoutScale(trackId, steps):
 #Other functions. These can't be template functions because they use a specific track and Patroneos row and scale system.
 def noteOn(trackId, row):
     track = session.data.trackById(trackId)
+    if not track: return
     midipitch = track.pattern.scale[row]
     cbox.send_midi_event(0x90+track.midiChannel, midipitch, track.pattern.averageVelocity, output=track.cboxMidiOutAbstraction)
 
 def noteOff(trackId, row):
     track = session.data.trackById(trackId)
+    if not track: return
     midipitch = track.pattern.scale[row]
     cbox.send_midi_event(0x80+track.midiChannel, midipitch, track.pattern.averageVelocity, output=track.cboxMidiOutAbstraction)
 

template/engine/sequencer.py

@@ -61,6 +61,7 @@ class Score(Data):
         self.tracks = [] #see docstring
         self.tempoMap = TempoMap(parentData = self)
         self._template_processAfterInit()
+        self._tracksFailedLookup = []
 
     def _template_processAfterInit(self): #needs a different name because there is an inherited class with the same method.
         """Call this after either init or instanceFromSerializedData"""
@@ -119,11 +120,21 @@ class Score(Data):
         except Exception as e: #No Jack Meta Data or Error with ports.
             logger.error(e)
 
+
     def trackById(self, trackId:int):
+        """Returns a track or None, if not found"""
         for track in self.tracks:
             if trackId == id(track):
                 return track
-        raise ValueError(f"Track {trackId} not found. Current Tracks: {[id(tr) for tr in self.tracks]}")
+        else:
+            #Previously this crashed with a ValueError. However, after a rare bug that a gui widget focussed out because a track was deleted and then tried to send its value to the engine we realize that this lookup can gracefully return None.
+            #Nothing will break: Functions that are not aware yet, that None is an option will crash when they try to access None as a track object. For this case we present the following logger error:
+            if not trackId in self._tracksFailedLookup:
+                logger.error(f"Track {trackId} not found. Current Tracks: {[id(tr) for tr in self.tracks]}")
+                self._tracksFailedLookup.append(trackId) #prevent multiple error messages for the same track in a row.
+                return None
+                #raise ValueError(f"Track {trackId} not found. Current Tracks: {[id(tr) for tr in self.tracks]}")
+
 
 
     #Save / Load / Export