Patroneo/qtgui/songeditor.py

#! /usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Copyright 2021, Nils Hilbricht, Germany ( https://www.hilbricht.net )

This file is part of Patroneo ( https://www.laborejo.org )

Laborejo is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

import logging; logger = logging.getLogger(__name__); logger.info("import")

from time import time
import engine.api as api #Session is already loaded and created, no duplication.
import template.qtgui.helper as helper

from PyQt5 import QtCore, QtGui, QtWidgets

SIZE_UNIT = 25 #this is in manual sync with timeline.py SIZE_UNIT
SIZE_TOP_OFFSET = 0

_zValuesRelativeToScene = { #Only use for objects added directly to the scene, not children.
    "trackStructure":3,
    "barline":5,
    "switch":6,
    "barlineGroupHighlight":8,
    "playhead":90,
}

class SongEditor(QtWidgets.QGraphicsScene):
    def __init__(self, parentView):
        super().__init__()
        self.parentView = parentView

        #Set color, otherwise it will be transparent in window managers or wayland that want that.
        self.backColor = QtGui.QColor(55, 61, 69)
        self.setBackgroundBrush(self.backColor)

        self._exportDictScore = None #cached

        #Subitems
        self.playhead = Playhead(parentScene = self)
        self.addItem(self.playhead)
        self.playhead.setY(SIZE_TOP_OFFSET)

        self.tracks = {} #TrackID:TrackStructures
        self.barlines = [] #in order

        self.cachedCombinedTrackHeight = 0 #set by callback_tracksChanged
        self.trackOrder = [] #contains engine-ids, set by callback_numberOfTracksChanged

        role = QtGui.QPalette.BrightText
        self.brightPen = QtGui.QPen(self.parentView.parentMainWindow.fPalBlue.color(role))
        self.normalPen = QtGui.QPen()

        api.callbacks.numberOfTracksChanged.append(self.callback_numberOfTracksChanged)
        api.callbacks.timeSignatureChanged.append(self.callback_timeSignatureChanged)
        api.callbacks.numberOfMeasuresChanged.append(self.callback_setnumberOfMeasures)

        api.callbacks.trackStructureChanged.append(self.callback_trackStructureChanged) #updates single tracks
        api.callbacks.exportCacheChanged.append(self.cacheExportDict)
        api.callbacks.scoreChanged.append(self.callback_scoreChanged) #sends information about measuresPerGroup
        api.callbacks.trackMetaDataChanged.append(self.callback_trackMetaDataChanged)
        api.callbacks.patternLengthMultiplicatorChanged.append(self.callback_patternLengthMultiplicatorChanged)

        #self.ticksToPixelRatio = None set by callback_timeSignatureChanged

    def wheelEvent(self, event):
        """zoom, otherwise ignore event"""
        if QtWidgets.QApplication.keyboardModifiers() == QtCore.Qt.ControlModifier:
            self.parentView.parentMainWindow.zoomUpperHalf(event.delta())
            event.accept()
        else:
            event.ignore()
            super().wheelEvent(event)

    def callback_trackMetaDataChanged(self, exportDict):
        """This is not for the initial track creation, only for later changes"""
        self.tracks[exportDict["id"]].updateMetaData(exportDict)

    def cacheExportDict(self, exportDict):
        """Does not get called on structure change because callback_trackStructureChanged
        also caches the exportDict """
        self.tracks[exportDict["id"]].exportDict = exportDict

    def callback_trackStructureChanged(self, exportDict):
        """Happens if a switch gets flipped"""
        track = self.tracks[exportDict["id"]]
        track.updateSwitches(exportDict)

    def callback_timeSignatureChanged(self, nr, typ):
        oneMeasureInTicks = nr * typ
        self.ticksToPixelRatio = oneMeasureInTicks / SIZE_UNIT

    def callback_numberOfTracksChanged(self, exportDictList):
        """Used for new tracks, delete track and move track"""
        toDelete = set(self.tracks.keys())
        self.trackOrder = []

        for index, exportDict in enumerate(exportDictList):
            if exportDict["id"] in self.tracks:
                toDelete.remove(exportDict["id"]) #keep this track and don't delete later.
            else:  #new track
                self.tracks[exportDict["id"]] = TrackStructure(parentScene=self)
                self.addItem(self.tracks[exportDict["id"]])
                self.tracks[exportDict["id"]].setZValue(_zValuesRelativeToScene["trackStructure"])

            self.trackOrder.append(self.tracks[exportDict["id"]])
            self.tracks[exportDict["id"]].setY(index * SIZE_UNIT + SIZE_TOP_OFFSET)
            self.tracks[exportDict["id"]].updateSwitches(exportDict)
            self.tracks[exportDict["id"]].updateStaffLines(exportDict["numberOfMeasures"])

        #We had these tracks in the GUI but they are gone in the export. This is track delete.
        for trackId in toDelete:
            trackStructure = self.tracks[trackId]
            for position, switch in trackStructure.switches.items():
                self.removeItem(switch) #switches are direct children of the scene. delete them here.
            #we don't need to delete from trackOrder here because that is cleared each time we call this function
            del self.tracks[trackId]
            self.removeItem(trackStructure) #remove from scene
            del trackStructure

        assert all(track.exportDict["sequencerInterface"]["index"] == self.trackOrder.index(track) for track in self.tracks.values())
        self.cachedCombinedTrackHeight = len(self.tracks) * SIZE_UNIT
        self.setSceneRect(0,0,exportDict["numberOfMeasures"]*SIZE_UNIT,self.cachedCombinedTrackHeight + 3*SIZE_TOP_OFFSET) #no empty space on top without a scene rect. Also a bit of leniance.
        self.playhead.setLine(0, 0, 0, self.cachedCombinedTrackHeight) #(x1, y1, x2, y2)
        self.adjustBarlineHeightForNewTrackCount()

    def adjustBarlineHeightForNewTrackCount(self):
        """Fetches the current context itself and modifies all existing barlines.
        """
        for barline in self.barlines:
            barline.setLine(0,0,0,self.cachedCombinedTrackHeight)

    def callback_setnumberOfMeasures(self, exportDictScore):
        self._exportDictScore = exportDictScore
        requestAmountOfMeasures = exportDictScore["numberOfMeasures"]
        requestAmountOfMeasures += 1 #the final closing barline
        maximumAmountIncludingHidden = len(self.barlines)

        if requestAmountOfMeasures == maximumAmountIncludingHidden:
            for l in self.barlines: l.show()
        elif requestAmountOfMeasures > maximumAmountIncludingHidden: #we need more than we have. Maybe new ones.
            for l in self.barlines: l.show()
            for i in range(maximumAmountIncludingHidden, requestAmountOfMeasures):
                barline = QtWidgets.QGraphicsLineItem(0,0,0,1) #correct length will be set below, but we need something other than 0 here
                self.addItem(barline)
                barline.setAcceptedMouseButtons(QtCore.Qt.NoButton) #barlines will intercept clicks on the track otherwise. We keep the horizontal stafflines blocking to prevent accidents though.
                barline.setPos(i*SIZE_UNIT, SIZE_TOP_OFFSET)
                barline.setEnabled(False)
                barline.setZValue(_zValuesRelativeToScene["barline"])
                self.barlines.append(barline)
        else: #user reduced the number of barlines. We only hide, never delete.
            for l in self.barlines[requestAmountOfMeasures:]:
                l.hide()

        #Guaranteed visible.
        for l in self.barlines[:requestAmountOfMeasures]:
            l.show()

        self.callback_scoreChanged(exportDictScore)  #colors from the start

        self.adjustBarlineHeightForNewTrackCount() #otherwise only the new ones have the correct height.

        self.setSceneRect(0,0,requestAmountOfMeasures*SIZE_UNIT,self.cachedCombinedTrackHeight + 3*SIZE_TOP_OFFSET) #no empty space on top without a scene rect

        for track in self.tracks.values():
            factor = track.exportDict["patternLengthMultiplicator"]
            track.updateSwitchVisibility(requestAmountOfMeasures=(requestAmountOfMeasures-1) // factor)
            track.updateStaffLines(requestAmountOfMeasures-1)

    def callback_scoreChanged(self, exportDictScore):
        self._exportDictScore = exportDictScore
        self.measuresPerGroupCache = exportDictScore["measuresPerGroup"]
        for i,barline in enumerate(self.barlines):
            if i > 0 and (i+1) % exportDictScore["measuresPerGroup"] == 1:
                barline.setPen(self.brightPen)
                barline.setZValue(_zValuesRelativeToScene["barlineGroupHighlight"])
            else:
                barline.setPen(self.normalPen)
                barline.setZValue(_zValuesRelativeToScene["barline"])


    def callback_patternLengthMultiplicatorChanged(self, exportDict):
        """This is only for a single track. We relay it"""
        track = self.tracks[exportDict["id"]]
        track.updatePatternLengthMultiplicator(exportDict)


class TrackStructure(QtWidgets.QGraphicsRectItem):
    """From left to right. Holds two lines to show the "staffline" and a number of switches,
    colored rectangles to indicate where a pattern is activated on the timeline"""

    def __init__(self, parentScene):
        super().__init__(0,0,1,SIZE_UNIT)
        self.parentScene = parentScene
        self.setAcceptHoverEvents(True) #for the preview highlight switch

        self.exportDict = None #self.update gets called immediately after creation.
        self.switches = {} # position:switchInstance

        self.currentColor = None #set in updateMetaData
        self.labelColor = None #set in updateMetaData for redable labels on our color. for example transpose number
        #The track holds the horizontal lines. The number of barlines is calculated in the parentScene for all tracks at once.
        self.topLine = QtWidgets.QGraphicsLineItem(0,0,1,0) #empty line is not possible. We need at least something to let self.update work with
        self.topLine.setParentItem(self)
        self.topLine.setPos(0,0)
        self.bottomLine = QtWidgets.QGraphicsLineItem(0,0,1,0) #empty line is not possible. We need at least something to let self.update work with
        self.bottomLine.setParentItem(self)
        self.bottomLine.setPos(0,SIZE_UNIT)

        self.topLine.setEnabled(False)
        self.bottomLine.setEnabled(False)

        #Interactive Marker to select several switches in a row
        self._mousePressOn = None #to remember the position of a mouse click
        #self._markerLine = QtWidgets.QGraphicsLineItem(0,0,10,0) #only updated, never replaced
        self._markerLine = QtWidgets.QGraphicsRectItem(0,0,10,SIZE_UNIT) #only updated, never replaced
        #self._markerLine.setParentItem(self) #incompatible with zValues. We need this relative to the scene
        self.parentScene.addItem(self._markerLine)
        #self._markerLine.setY(self.pos().y()) #won't work yet. We are not in the scene ourselves. We set it in mousePressEvent, before show()
        self._markerLine.setZValue(_zValuesRelativeToScene["switch"])
        self._markerLine.hide()

        #Semitransparent hover-switch to show which one would be activated/deactivated
        #Color and position is set in the callbacks and mouse handling
        #It is below the actual switch so it will not show when there is already a switch, which is ok
        self._highlightSwitch = QtWidgets.QGraphicsRectItem(0,0,SIZE_UNIT, SIZE_UNIT)
        self._highlightSwitch.setParentItem(self)
        self._highlightSwitch.setOpacity(0.2)
        self._highlightSwitch.hide()

    def _setColors(self, exportDict):
        """Called from various callbacks like updateSwitches and updateMetadata"""
        self.exportDict = exportDict
        c = QtGui.QColor(exportDict["color"])
        self.currentColor = c

        self._highlightSwitch.setBrush(c) #this is with low opacity.

        if c.lightness() > 127: #between 0 (for black) and 255 (for white)
            labelColor = QtGui.QColor("black")
        else:
            labelColor = QtGui.QColor("white")
        self.labelColor = labelColor #save for new switches


    def updateSwitches(self, exportDict):
        self.exportDict = exportDict
        self._setColors(exportDict)

        #Create new switches
        for position in exportDict["structure"]:
            if not position in self.switches:
                self.switches[position] = self._createSwitch(position)

        factor = exportDict["patternLengthMultiplicator"]
        effectiveNumberOfMeasures = exportDict["numberOfMeasures"] // factor  # //integer division
        self.updateSwitchVisibility(effectiveNumberOfMeasures)

    def updateMetaData(self, exportDict):
        """Color and Transposition status.
        Does not get called on track structure change."""
        self.exportDict = exportDict
        self._setColors(exportDict)

        for switch in self.switches.values():
            switch.setBrush(self.currentColor)
            switch.setScaleTransposeColor(self.labelColor)
            switch.setHalftoneTransposeColor(self.labelColor)

    def updatePatternLengthMultiplicator(self, exportDict):
        """Comes via its own callback, also named callback_patternLengthMultiplicatorChanged.
        The spinBox to set this is in TrackLabel"""
        self.updateSwitches(exportDict) # contains exportDict caching.
        effectiveNumberOfMeasures = exportDict["numberOfMeasures"] // exportDict["patternLengthMultiplicator"]  # //integer division
        #self.updateStaffLines(effectiveNumberOfMeasures) #we do not need to adjust the overall track length. That stays the same, no matter the factor.

    def updateStaffLines(self, requestAmountOfMeasures):
        """The two horizontal lines that mark our track.
        We do NOT need to handle patternLengthMultiplicator since the overall track length
        stays the same. Just the measure divisions are different.
        """
        l = self.topLine.line()
        l.setLength(requestAmountOfMeasures * SIZE_UNIT)
        self.topLine.setLine(l)

        l = self.bottomLine.line()
        l.setLength(requestAmountOfMeasures * SIZE_UNIT)
        self.bottomLine.setLine(l)

        #Update self, which is the track background
        self.setRect(0,0,requestAmountOfMeasures * SIZE_UNIT, SIZE_UNIT)

    def _createSwitch(self, position):
        """Called only by self.updateSwitches
        Qt can't put the same item into the scene twice. We need to create a new one each time"""
        switch = Switch(parentTrackStructure=self, position=position)
        assert self.currentColor
        switch.setBrush(self.currentColor)
        #switch.setParentItem(self)  #prevents zValue because switches are children of trackStructure. add to scene directly instead:

        #For now we assume no stretch factor. One measure is one base measure.
        #We set that in self.updateSwitchVisibility
        self.scene().addItem(switch)
        switch.setPos(position * SIZE_UNIT, self.y())
        switch.setZValue(_zValuesRelativeToScene["switch"])
        return switch

    def updateSwitchVisibility(self, requestAmountOfMeasures):
        """Switch pattern-visibility on and off.
        This never creates or deletes switches
        We assume self.exportDict is up to date
        because we get called by self.updateSwitches, which saves the exportDict."""
        structure = self.exportDict["structure"]
        whichPatternsAreScaleTransposed = self.exportDict["whichPatternsAreScaleTransposed"]
        whichPatternsAreHalftoneTransposed = self.exportDict["whichPatternsAreHalftoneTransposed"]
        factor = self.exportDict["patternLengthMultiplicator"]

        #requestAmountOfMeasures = requestAmountOfMeasures // factor  #already is.

        #Adjust highlight mouse hover to new stretch factor
        r = self._highlightSwitch.rect()
        r.setRight(SIZE_UNIT * factor)
        self._highlightSwitch.setRect(r)

        for position, switch in self.switches.items():
            #Deal with measures that stretch multiple base measures
            switch.stretch(factor)
            switch.setPos(position * SIZE_UNIT * factor, self.y())

            #both position and requestAmountOfMeasures below are adjusted with scale factors
            if not position in structure:
                switch.hide() #Not delete because this may be just a temporary reduction of measures
                switch.scaleTransposeOff()
            elif position >= requestAmountOfMeasures: #switch is out of bounds. For factor 1 this is the same as not in the score-area
                switch.hide()
                switch.scaleTransposeOff()
            else:
                switch.show()

            if position in whichPatternsAreScaleTransposed:
                switch.setScaleTranspose(-1 * whichPatternsAreScaleTransposed[position]) #we flip the polarity from "makes sense" to row based "lower is higher" here. The opposite, sending, flip is done in switch hover leave event
            else:
                switch.scaleTransposeOff()

            if position in whichPatternsAreHalftoneTransposed:
                switch.setHalftoneTranspose(whichPatternsAreHalftoneTransposed[position]) #half tone transposition is not flipped
            else:
                switch.halftoneTransposeOff()


    def contextMenuEvent(self, event):
        if self._mousePressOn: #Right click can happen while the left button is still pressed down, which we don't want.
            return
        menu = QtWidgets.QMenu()


        position = self.scenePos2switchPosition(event.scenePos().x()) #measure number 0 based
        position = position * self.exportDict["patternLengthMultiplicator"] #We need the position in the global system, without the factor
        measuresPerGroup = self.parentScene.measuresPerGroupCache
        offset = position % measuresPerGroup
        startMeasureForGroup = position - offset
        endMeasureExclusive = startMeasureForGroup + measuresPerGroup

        listOfLabelsAndFunctions = [
            (QtCore.QCoreApplication.translate("SongStructure", "Insert empty group before this one"), lambda: api.insertSilence(howMany=measuresPerGroup, beforeMeasureNumber=startMeasureForGroup)),
            (QtCore.QCoreApplication.translate("SongStructure", "Exchange group with right neigbour"), lambda: api.exchangeSwitchGroupWithGroupToTheRight(startMeasureForGroup, endMeasureExclusive)),
            (QtCore.QCoreApplication.translate("SongStructure", "Delete whole group"), lambda: api.deleteSwitches(howMany=measuresPerGroup, fromMeasureNumber=startMeasureForGroup)),
            (QtCore.QCoreApplication.translate("SongStructure", "Duplicate whole group including measures"), lambda: api.duplicateSwitchGroup(startMeasureForGroup, endMeasureExclusive)),
            (QtCore.QCoreApplication.translate("SongStructure", "Clear all group transpositions"), lambda: api.clearSwitchGroupTranspositions(startMeasureForGroup, endMeasureExclusive)),
            ]

        for text, function in listOfLabelsAndFunctions:
            a = QtWidgets.QAction(text, menu)
            menu.addAction(a)
            a.triggered.connect(function)

        pos = QtGui.QCursor.pos()
        pos.setY(pos.y() + 5)
        self.parentScene.parentView.parentMainWindow.setFocus()
        menu.exec_(pos)

    def scenePos2switchPosition(self, x):
        """Map scene coordinates to counted switch engine position"""
        factor = self.exportDict["patternLengthMultiplicator"]
        return int(x / SIZE_UNIT / factor)

    def mousePressEvent(self, event):
        #First we need to find the mouse clicks position. self.switches only holds pos that were at least activated once.
        #The track is only the area where the rectangles and lines meet. it is impossible to click below or right of the tracks.
        #we always get a valid position this way.

        if event.button() == QtCore.Qt.MiddleButton and not self._mousePressOn:
            self.parentScene.parentView.parentMainWindow.patternGrid.createShadow(self.exportDict)
        else:
            self.parentScene.parentView.parentMainWindow.chooseCurrentTrack(self.exportDict)
            if event.button() == QtCore.Qt.LeftButton: #Create a switch or continue to hold down mouse button and drag to draw -> mouseMoveEvent
                assert not self._mousePressOn
                position = self.scenePos2switchPosition(event.scenePos().x()) #measure number 0 based
                self._markerLine.setX(position * SIZE_UNIT * self.exportDict["patternLengthMultiplicator"])
                self._markerLine.setY(self.pos().y()) #we can't do that in init because self is not in the scene by then. markerLine is a child directly to the scene, no magic reparenting.
                newBool = not position in self.switches or not self.switches[position].isVisible()
                if newBool:
                    self._markerLine.setBrush(self.currentColor)
                else:
                    self._markerLine.setBrush(self.parentScene.parentView.parentMainWindow.fPalBlue.color(QtGui.QPalette.AlternateBase)) #we are always the active track so this is our color

                self._mousePressOn = (time(), self, position, newBool) #Reset to None in mouseReleaseEvent
                result = api.setSwitch(self.exportDict["id"], position, newBool) #returns True if a switch happend

            #elif event.button() == QtCore.Qt.RightButton and not self._mousePressOn:
            #no, this is done with contextMenuEvent directly so it also reacts to the context menu keyboard key.


    def mouseMoveEvent(self, event):
        """Draw new switches by holding and dragging the mouse
        This is only the visual aspect. Actual calcuation and insert is in mouseReleaseEvent
        The initial _markerLine is setup in mousePressEvent, where the first switch is already set as well

        In Patroneo this is only triggered when left mouse button is down.
        We don't set the Qt flag to always react"""
        position = self.scenePos2switchPosition(event.scenePos().x()) #measure number 0 based
        factor = self.exportDict["patternLengthMultiplicator"]
        if self._mousePressOn and position != self._mousePressOn[2]:
            #self._markerLine.setLine(0,0, (position - self._mousePressOn[2])*SIZE_UNIT + SIZE_UNIT/2, 0)
            rect = self._markerLine.rect()
            if position < 0:
                position = 0
            elif position + 1  > self.exportDict["numberOfMeasures"]: #position is already a switch position
                position = self.exportDict["numberOfMeasures"] - 1

            if position < self._mousePressOn[2]:
                left = (position - self._mousePressOn[2]) * SIZE_UNIT
                rect.setLeft(left*factor)
                rect.setRight(SIZE_UNIT)
            else:
                right = (position - self._mousePressOn[2]) * SIZE_UNIT + SIZE_UNIT
                rect.setRight(right*factor)
                rect.setLeft(0)

            self._markerLine.setRect(rect)
            self._markerLine.show()
        else:
            self._markerLine.hide()

    def hoverEnterEvent(self, event):
        self._highlightSwitch.show()
        #This seemed to be a good idea but horrible UX. If you move the mouse down to edit a pattern you end up choosing the last track
        #self.scene().parentView.parentMainWindow.chooseCurrentTrack(self.exportDict)

    def hoverLeaveEvent(self, event):
        self._highlightSwitch.hide()

    def hoverMoveEvent(self, event):
        """Snap the highlight switch to grid and stretch factor"""
        #x = round((event.scenePos().x() / SIZE_UNIT)-1) * SIZE_UNIT
        switchPos = self.scenePos2switchPosition(event.scenePos().x())
        factor = self.exportDict["patternLengthMultiplicator"]
        x = switchPos * SIZE_UNIT * factor
        self._highlightSwitch.setX(x)


    def mouseReleaseEvent(self, event):
        if event.button() == QtCore.Qt.LeftButton:
            self._markerLine.hide()
            position = self.scenePos2switchPosition(event.scenePos().x())
            if position < 0:
                position = 0
            elif position +1 > self.exportDict["numberOfMeasures"]: #position is already a switch position
                position = self.exportDict["numberOfMeasures"] -1

            startTime, startTrack, startPosition, setTo = self._mousePressOn
            self._mousePressOn = None
            if not startPosition == position and time() - startTime > 0.4: #optimisation to spare the engine from redundant work. Also prevent hectic drag-clicking
                #setTo is a bool that tells us if all the switches in our range should go on (True) or off (False). The first switch, startPosition, is already set in mousePressEvent for a better user experience.
                low, high = sorted((startPosition, position)) #both included
                setOfPositions = set(range(low, high+1)) #range does not include the last one, we want it in. it MUST be a set.
                api.setSwitches(self.exportDict["id"], setOfPositions, setTo)

    def mark(self, boolean):
        """Mark the whole Track as active or not"""
        if boolean:
            role = QtGui.QPalette.AlternateBase
        else:
            role = QtGui.QPalette.Base
        c = self.parentScene.parentView.parentMainWindow.fPalBlue.color(role)
        self.setBrush(c)

class Switch(QtWidgets.QGraphicsRectItem):
    """Switches live for the duration of the track. Once created they only ever get hidden/shown,
    never deleted.

    Not every "empty square" has a switch already. Only switches that were activated at least once.
    """
    def __init__(self, parentTrackStructure, position):
        self.parentTrackStructure = parentTrackStructure
        self.position = position
        super().__init__(0,0,SIZE_UNIT,SIZE_UNIT)

        #self.rect().setWidth(SIZE_UNIT)

        self.setAcceptHoverEvents(True)

        self.scaleTransposeGlyph = QtWidgets.QGraphicsSimpleTextItem("")
        self.scaleTransposeGlyph.setParentItem(self)
        self.scaleTransposeGlyph.setScale(0.80)
        self.scaleTransposeGlyph.setPos(2,1)
        self.scaleTransposeGlyph.setBrush(self.parentTrackStructure.labelColor)
        self.scaleTransposeGlyph.hide()
        self.scaleTranspose = 0

        self.halftoneTransposeGlyph = QtWidgets.QGraphicsSimpleTextItem("")
        self.halftoneTransposeGlyph.setParentItem(self)
        self.halftoneTransposeGlyph.setScale(0.80)
        self.halftoneTransposeGlyph.setPos(1,13)
        self.halftoneTransposeGlyph.setBrush(self.parentTrackStructure.labelColor)
        self.halftoneTransposeGlyph.hide()
        self.halftoneTranspose = 0

    def stretch(self, factor):
        """factor assumes relative to SIZE_UNIT"""
        r = self.rect()
        r.setRight(SIZE_UNIT * factor)
        self.setRect(r)


    def setScaleTranspose(self, value):
        """
        Called by track callbacks and also for the temporary buffer display

        while internally both the engine and us, the GUI, use steps and transposition through
        "negative is higher pitch" we present it reversed for the user.
        Greater number is higher pitch

        It is guaranteed that only active switches can have a transposition.
        Also transposition=0 is not included.
        """
        self.scaleTranspose = value
        self._setScaleTransposeLabel(value)

    def _setScaleTransposeLabel(self, value):
        text = ("+" if value > 0 else "") + str(value) + "s"
        self.scaleTransposeGlyph.setText(text)
        self.scaleTransposeGlyph.show()

    def setScaleTransposeColor(self, c):
        self.scaleTransposeGlyph.setBrush(c)

    def scaleTransposeOff(self):
        self.scaleTransposeGlyph.setText("")
        #self.scaleTransposeGlyph.hide()
        self.scaleTranspose = 0
        self._bufferScaleTranspose = 0

    def setHalftoneTranspose(self, value):
        self.halftoneTranspose = value
        self._setHalftoneTransposeLabel(value)

    def _setHalftoneTransposeLabel(self, value):
        text = ("+" if value > 0 else "") + str(value) + "h"
        self.halftoneTransposeGlyph.setText(text)
        self.halftoneTransposeGlyph.show()

    def setHalftoneTransposeColor(self, c):
        self.halftoneTransposeGlyph.setBrush(c)

    def halftoneTransposeOff(self):
        self.halftoneTransposeGlyph.setText("")
        #self.halftoneTransposeGlyph.hide()
        self.halftoneTranspose = 0
        self._bufferhalftoneTranspose = 0

    def mousePressEvent(self, event):
        """A mouse events on the track activate a switch. Then we receive the event to turn it
        off again."""
        event.ignore()

    def hoverEnterEvent(self, event):
        self._bufferScaleTranspose = self.scaleTranspose
        self._bufferHalftoneTranspose = self.halftoneTranspose

    def hoverLeaveEvent(self, event):
        """only triggered when active/shown"""
        event.accept()

        #Scale Transpose. Independent of Halftone Transpose
        if not self._bufferScaleTranspose == self.scaleTranspose:
            api.setSwitchScaleTranspose(self.parentTrackStructure.exportDict["id"], self.position, -1*self._bufferScaleTranspose) #we flip the polarity here. The receiving flip is done in the callback.
            #new transpose/buffer gets set via callback
        if self._bufferScaleTranspose == 0:
            self.scaleTransposeOff()

        #Halftone Transpose. Independent of Scale Transpose
        if not self._bufferHalftoneTranspose == self.halftoneTranspose:
            api.setSwitchHalftoneTranspose(self.parentTrackStructure.exportDict["id"], self.position, self._bufferHalftoneTranspose)  #half tone transposition is not flipped
            #new transpose/buffer gets set via callback
        if self._bufferHalftoneTranspose == 0:
            self.halftoneTransposeOff()

    def wheelEvent(self, event):
        """Does not get triggered when switch is off.
        This buffers until hoverLeaveEvent and then the new value is sent in self.hoverLeaveEvent"""
        event.accept()

        if QtWidgets.QApplication.keyboardModifiers() == QtCore.Qt.ShiftModifier: #half tone transposition
            if event.delta() > 0:
                self._bufferHalftoneTranspose = min(+24, self._bufferHalftoneTranspose+1)
            else:
                self._bufferHalftoneTranspose = max(-24, self._bufferHalftoneTranspose-1)
            self._setHalftoneTransposeLabel(self._bufferHalftoneTranspose)

        else: #scale transposition
            if event.delta() > 0:
                self._bufferScaleTranspose = min(+7, self._bufferScaleTranspose+1)
            else:
                self._bufferScaleTranspose = max(-7, self._bufferScaleTranspose-1)
            self._setScaleTransposeLabel(self._bufferScaleTranspose)

class TrackLabelEditor(QtWidgets.QGraphicsScene):
    """Only the track labels"""
    def __init__(self, parentView):
        super().__init__()
        self.parentView = parentView
        self.tracks = {} #TrackID:TrackLabel

        self._cachedExportDictsInOrder = []
        self._exportDictScore = None #cache

        #Set color, otherwise it will be transparent in window managers or wayland that want that.
        self.backColor = QtGui.QColor(55, 61, 69)
        self.backColor = QtGui.QColor(48, 53, 60)
        self.setBackgroundBrush(self.backColor)

        api.callbacks.numberOfTracksChanged.append(self.callback_numberOfTracksChanged)
        api.callbacks.trackMetaDataChanged.append(self.callback_trackMetaDataChanged)
        api.callbacks.numberOfMeasuresChanged.append(self.callback_setnumberOfMeasures)
        api.callbacks.exportCacheChanged.append(self.cacheExportDict)
        api.callbacks.patternLengthMultiplicatorChanged.append(self.callback_patternLengthMultiplicatorChanged)

        self.cachedCombinedTrackHeight = 0 #set by callback_tracksChanged

    def cacheExportDict(self, exportDict):
        self.tracks[exportDict["id"]].exportDict = exportDict

    def callback_trackMetaDataChanged(self, exportDict):
        """This is not for the initial track creation, only for later changes"""
        self.tracks[exportDict["id"]].update(exportDict)

    def callback_setnumberOfMeasures(self, exportDictScore):
        self._exportDictScore = exportDictScore

    def callback_numberOfTracksChanged(self, exportDictList):

        toDelete = set(self.tracks.keys())

        self._cachedExportDictsInOrder = exportDictList

        width = self.parentView.geometry().width()


        for index, exportDict in enumerate(exportDictList):
            if exportDict["id"] in self.tracks:
                toDelete.remove(exportDict["id"])
            else:  #new track
                self.tracks[exportDict["id"]] = TrackLabel(parentScene=self, width=width, height=SIZE_UNIT)
                self.addItem(self.tracks[exportDict["id"]])

            self.tracks[exportDict["id"]].setY(index * SIZE_UNIT + SIZE_TOP_OFFSET)
            self.tracks[exportDict["id"]].update(exportDict)


        #We had this tracks in the GUI but they are gone in the export. This is track delete.
        for trackId in toDelete:
            trackLabel = self.tracks[trackId]
            del self.tracks[trackId]
            self.removeItem(trackLabel) #remove from scene
            del trackLabel
        if toDelete and self.parentView.parentMainWindow.currentTrackId in toDelete: #toDelete still exist if tracks were deleted above
            anyExistingTrack = next(iter(self.tracks.values()))
            self.parentView.parentMainWindow.chooseCurrentTrack(anyExistingTrack.exportDict)

        self.cachedCombinedTrackHeight = len(self.tracks) * SIZE_UNIT
        self.setSceneRect(0,0,width-1,self.cachedCombinedTrackHeight + 3*SIZE_TOP_OFFSET)


    def callback_patternLengthMultiplicatorChanged(self, exportDict):
        self.tracks[exportDict["id"]].update(exportDict) #general update function that also covers our value

    def contextMenuEvent(self, event):
        """
        We can't delete this properly object from within. The engine callback will react faster
        than we need to finish this function. That means qt and python will try to access
        objects that are non-existent"""

        menu = QtWidgets.QMenu()

        item = self.itemAt(event.scenePos().x(), event.scenePos().y(), self.parentView.transform())
        if not type(item) is QtWidgets.QGraphicsProxyWidget:
            return None

        exportDict = item.parentItem().exportDict.copy()
        del item #yes, manual memory management in Python. We need to get rid of anything we want to delete later or Qt will crash because we have a python wrapper without a qt object

        listOfLabelsAndFunctions = [
            (exportDict["sequencerInterface"]["name"], None),
            (QtCore.QCoreApplication.translate("TrackLabelContext", "Invert Measures"), lambda: api.trackInvertSwitches(exportDict["id"])),
            (QtCore.QCoreApplication.translate("TrackLabelContext", "All Measures On"), lambda: api.trackOnAllSwitches(exportDict["id"])),
            (QtCore.QCoreApplication.translate("TrackLabelContext", "All Measures Off"), lambda: api.trackOffAllSwitches(exportDict["id"])),
            (QtCore.QCoreApplication.translate("TrackLabelContext", "Clone this Track"), lambda: api.createSiblingTrack(exportDict["id"])),
            (QtCore.QCoreApplication.translate("TrackLabelContext", "Delete Track"), lambda: api.deleteTrack(exportDict["id"])),
            ]

        for text, function in listOfLabelsAndFunctions:
            if function is None:
                l = QtWidgets.QLabel(text)
                l.setAlignment(QtCore.Qt.AlignCenter)
                a = QtWidgets.QWidgetAction(menu)
                a.setDefaultWidget(l)
                menu.addAction(a)
            else:
                a = QtWidgets.QAction(text, menu)
                menu.addAction(a)
                a.triggered.connect(function)

        #Add a submenu for merge/cop

        mergeMenu = menu.addMenu(QtCore.QCoreApplication.translate("TrackLabelContext", "Merge/Copy Measure-Structure from"))

        def createCopyMergeLambda(srcId):
            return lambda: api.trackMergeCopyFrom(srcId, exportDict["id"])

        for sourceDict in self._cachedExportDictsInOrder:
            a = QtWidgets.QAction(sourceDict["sequencerInterface"]["name"], mergeMenu)
            mergeMenu.addAction(a)
            mergeCommand = createCopyMergeLambda(sourceDict["id"])
            if sourceDict["id"] == exportDict["id"]:
                a.setEnabled(False)
            a.triggered.connect(mergeCommand)

        #Add a submenu for pattern merge/copy
        copyMenu = menu.addMenu(QtCore.QCoreApplication.translate("TrackLabelContext", "Replace Pattern with"))

        def replacePatternWithLambda(srcId):
            return lambda: api.trackPatternReplaceFrom(srcId, exportDict["id"])

        for sourceDict in self._cachedExportDictsInOrder:
            a = QtWidgets.QAction(sourceDict["sequencerInterface"]["name"], copyMenu)
            copyMenu.addAction(a)
            mergeCommand = replacePatternWithLambda(sourceDict["id"])
            if sourceDict["id"] == exportDict["id"]:
                a.setEnabled(False)
            a.triggered.connect(mergeCommand)

        #Add a submenu to set the midi channel of this track. Highlight the current one
        midiChannelMenu = menu.addMenu(QtCore.QCoreApplication.translate("TrackLabelContext", "Send on MIDI Channel"))
        for mch in range(1, 17):
            mchAction =  QtWidgets.QAction(str(mch), midiChannelMenu)
            midiChannelMenu.addAction(mchAction)
            midiChannelCommand = lambda discard, chArg=mch: api.changeTrackMidiChannel(exportDict["id"], chArg) #discard parameter given by QAction
            if exportDict["midiChannel"] == mch:
                mchAction.setEnabled(False)
            mchAction.triggered.connect(midiChannelCommand)

        pos = QtGui.QCursor.pos()
        pos.setY(pos.y() + 5)
        self.parentView.parentMainWindow.setFocus()
        menu.exec_(pos)

class TrackLabel(QtWidgets.QGraphicsRectItem):
    def __init__(self, parentScene, width, height):
        super().__init__(0, 0, width, height)
        self.parentScene = parentScene
        self.setPen(QtGui.QPen(QtCore.Qt.NoPen))
        self.setFlag(self.ItemIgnoresTransformations) #zoom will repostion but not make the font bigger.

        #Child widgets. SIZE_UNIT is used as positioning block. Multiply yourself :)

        self.positioningHandle = TrackLabel.PositioningHandle(parentTrackLabel=self)
        self.positioningHandle.setParentItem(self)
        self.positioningHandle.setPos(0,0)
        self.positioningHandle.setToolTip(QtCore.QCoreApplication.translate("TrackLabel", "grab and move to reorder tracks"))

        self.lengthMultiplicatorSpinBox = TrackLabel.lengthMultiplicatorSpinBox(parentTrackLabel=self)
        self.lengthMultiplicatorSpinBox.setParentItem(self)
        self.lengthMultiplicatorSpinBox.setPos(SIZE_UNIT,0)

        self.colorButton = TrackLabel.ColorPicker(parentTrackLabel=self)
        self.colorButton.setParentItem(self)
        self.colorButton.setPos(4*SIZE_UNIT, 3)
        self.colorButton.setToolTip(QtCore.QCoreApplication.translate("TrackLabel", "change track color"))

        self.lineEdit = TrackLabel.NameLineEdit(parentTrackLabel=self)
        self.label = QtWidgets.QGraphicsProxyWidget()
        self.label.setWidget(self.lineEdit)
        self.label.setParentItem(self)
        self.label.setPos(5*SIZE_UNIT+3,0)

    class lengthMultiplicatorSpinBox(QtWidgets.QGraphicsProxyWidget):
        def __init__(self, parentTrackLabel):
            super().__init__()

            self.parentTrackLabel = parentTrackLabel
            self.spinBox = QtWidgets.QSpinBox()
            self.spinBox.setSuffix("x")
            #self.spinBox.setFrame(True)
            self.spinBox.setMinimum(1)
            self.setWidget(self.spinBox)
            self.spinBox.valueChanged.connect(self.spinBoxValueChanged) #Callback for setting is in ParentTrackLabel.update

        def spinBoxValueChanged(self):
            self.parentTrackLabel.parentScene.parentView.parentMainWindow.chooseCurrentTrack(self.parentTrackLabel.exportDict)
            api.setTrackPatternLengthMultiplicator(self.parentTrackLabel.exportDict["id"], self.spinBox.value())


    class ColorPicker(QtWidgets.QGraphicsRectItem):
        def __init__(self, parentTrackLabel):
            super().__init__(0,0,SIZE_UNIT*0.75,SIZE_UNIT*0.75)
            self.parentTrackLabel = parentTrackLabel
            self.setBrush(QtGui.QColor("cyan"))

        def mousePressEvent(self, event):
            if event.button() == QtCore.Qt.LeftButton:
                self.parentTrackLabel.parentScene.parentView.parentMainWindow.chooseCurrentTrack(self.parentTrackLabel.exportDict)
                event.accept()
                colorDialog = QtWidgets.QColorDialog()
                color = colorDialog.getColor(self.brush().color()) #blocks
                if color.isValid(): #and not abort
                    #self.setBrush(color) #done via callback.
                    api.changeTrackColor(self.parentTrackLabel.exportDict["id"], color.name())
                #else:
                #    colorDialog.setStandardColor(self.brush().color())
            else:
                event.ignore()
            #super().mousePressEvent(event)

    class PositioningHandle(QtWidgets.QGraphicsEllipseItem):
        def __init__(self, parentTrackLabel):
            super().__init__(0,0,SIZE_UNIT-2,SIZE_UNIT-2)
            self.parentTrackLabel = parentTrackLabel
            self.setPen(QtGui.QPen(QtCore.Qt.NoPen))
            role = QtGui.QPalette.ToolTipBase
            c = self.parentTrackLabel.parentScene.parentView.parentMainWindow.fPalBlue.color(role)
            self.setBrush(c)
            self.setOpacity(0.08) #this is meant as a slight overlay/highlight of both the current track and the other tracks

            self.arrowLabel = QtWidgets.QGraphicsSimpleTextItem("↕")
            self.arrowLabel.setFlag(QtWidgets.QGraphicsItem.ItemIgnoresParentOpacity)
            self.arrowLabel.setParentItem(self)
            self.arrowLabel.setScale(1.6)
            self.arrowLabel.setPos(2,1)
            role = QtGui.QPalette.Text
            self.arrowLabel.setBrush(self.parentTrackLabel.parentScene.parentView.parentMainWindow.fPalBlue.color(role))

            self._cursorPosOnMoveStart = None

        def yPos2trackIndex(self, y):
            """0 based"""
            pos = round(y / SIZE_UNIT)
            pos = min(pos, len(self.parentTrackLabel.parentScene.tracks)-1)
            return pos

        def mouseMoveEvent(self, event):
            if self._cursorPosOnMoveStart:
                self.parentTrackLabel.setY(max(0, event.scenePos().y()))
            #super().mouseMoveEvent(event)  #with this the sync between cursor and item is off.

        def mousePressEvent(self, event):
            """release gets only triggered when mousePressEvent was on the same item.
            We don't need to worry about the user just releasing the mouse on this item"""
            self._posBeforeMove = self.parentTrackLabel.pos()
            self._cursorPosOnMoveStart = QtGui.QCursor.pos()

            self._lineCursor = self.parentTrackLabel.lineEdit.cursor()
            self.parentTrackLabel.mousePressEvent(event)
            #super().mousePressEvent(event) #with this in mouseMoveEvent does not work. IIRC because we do not set the movableFlag

        def mouseReleaseEvent(self, event):
            newIndex = self.yPos2trackIndex(self.parentTrackLabel.y()) #we need to save that first, right after this we reset the position
            self.parentTrackLabel.setPos(self._posBeforeMove) #In case the block was moved to a position where no track is (below the tracks) we just reset the graphics before anything happens. The user will never see this really
            self._posBeforeMove = None
            self._cursorPosOnMoveStart = None
            api.moveTrack(self.parentTrackLabel.exportDict["id"], newIndex)

    class NameLineEdit(QtWidgets.QLineEdit):
        def __init__(self, parentTrackLabel):
            super().__init__("")
            self.parentTrackLabel = parentTrackLabel
            self.setFrame(False)
            self.setMaxLength(25)
            self.setMinimumSize(QtCore.QSize(0, SIZE_UNIT))
            self.setStyleSheet("background-color: rgba(0,0,0,0)") #transparent so we see the RectItem color
            self.setReadOnly(True)
            self.setFocusPolicy(QtCore.Qt.ClickFocus) #nmo tab
            self.editingFinished.connect(self.sendToEngine)
            self.returnPressed.connect(self.enter)

        def mousePressEvent(self,event):
            """We also need to force this track as active"""
            event.accept() #we need this for doubleClick
            self.parentTrackLabel.parentScene.parentView.parentMainWindow.chooseCurrentTrack(self.parentTrackLabel.exportDict)
            #event.ignore() #send to parent instead
            #super().mousePressEvent(event)

        def mouseDoubleClickEvent(self, event):
            event.accept()
            self.setReadOnly(False)

        def enter(self):
            self.sendToEngine()

        def sendToEngine(self):
            self.setReadOnly(True)
            new = self.text()
            if not new == self.parentTrackLabel.exportDict["sequencerInterface"]["name"]:
                self.blockSignals(True)
                api.changeTrackName(self.parentTrackLabel.exportDict["id"], new)
                self.blockSignals(False)

        #def keyPressEvent(self, event):
        #    if event.key()) == QtCore.Qt.Key_Return:
        #        event.accept()
        #
        #    else:
        #        event.ignore()
        #        super().keyPressEvent(event)


    def update(self, exportDict):
        self.exportDict = exportDict
        self.lineEdit.setText(exportDict["sequencerInterface"]["name"])
        self.colorButton.setBrush(QtGui.QColor(exportDict["color"]))
        self.lengthMultiplicatorSpinBox.spinBox.blockSignals(True)
        self.lengthMultiplicatorSpinBox.spinBox.setValue(int(exportDict["patternLengthMultiplicator"]))
        self.lengthMultiplicatorSpinBox.spinBox.blockSignals(False)

    def mousePressEvent(self,event):
        self.parentScene.parentView.parentMainWindow.chooseCurrentTrack(self.exportDict)
        #event.ignore() #don't add that here. Will destroy mouseMove and Release events of child widgets

    #def mouseReleaseEvent(self, event):
    #    event.

    def mark(self, boolean):
        if boolean:
            role = QtGui.QPalette.AlternateBase
        else:
            role = QtGui.QPalette.Base
        c = self.parentScene.parentView.parentMainWindow.fPalBlue.color(role)
        self.setBrush(c)

class Playhead(QtWidgets.QGraphicsLineItem):
    def __init__(self, parentScene):
        super().__init__(0, 0,  0, 0)        # (x1, y1, x2, y2)
        self.parentScene = parentScene
        p = QtGui.QPen()
        p.setColor(QtGui.QColor("red"))
        p.setWidth(3)
        #p.setCosmetic(True)
        self.setPen(p)
        api.callbacks.setPlaybackTicks.append(self.setCursorPosition)
        self.setZValue(_zValuesRelativeToScene["playhead"])

    def setCursorPosition(self, tickindex, playbackStatus):
        """Set the playhead to the right position, but keep the viewport stable.
        Shift the entire "page" if the cursor becomes invisible because its steps outside the viewport"""
        x = tickindex / self.parentScene.ticksToPixelRatio
        self.setX(x)
        if playbackStatus: # api.duringPlayback:
            scenePos = self.parentScene.parentView.mapFromScene(self.pos())
            cursorViewPosX = scenePos.x() #the cursor position in View coordinates
            width = self.parentScene.parentView.geometry().width()
            if cursorViewPosX <= 0 or cursorViewPosX >= width: #"pageflip"
                self.parentScene.parentView.horizontalScrollBar().setValue(x)