Reimplement the grid with a simpler and faster version

qtgui/grid.py

@@ -36,6 +36,9 @@ from .constantsAndConfigs import constantsAndConfigs
 import engine.api as api
 
 
+gridPen = QtGui.QPen(QtCore.Qt.DotLine)
+gridPen.setCosmetic(True)
+
 masterLine = QtCore.QLineF(0, 0, 0, 128*constantsAndConfigs.stafflineGap)  # (x1, y1, x2, y2)
 class RhythmLine(QtWidgets.QGraphicsLineItem):
     def __init__(self, parentGrid):
@@ -44,8 +47,99 @@ class RhythmLine(QtWidgets.QGraphicsLineItem):
         self.setParentItem(parentGrid)
         self.setAcceptedMouseButtons(QtCore.Qt.NoButton) #we still need this otherwise no rubberband.
 
+class ActualGrid(QtWidgets.QGraphicsItem):
+
+    def boundingRect(self):
+        return self.childrenBoundingRect()
+
+class GuiGrid(QtWidgets.QGraphicsItem):
+    """Third version of the grid.
+    Version 1: QGraphicsItemGroup with horizontal and vertical lines.  Slow, disturbing to look at
+    even when the horizontal lines where nice ledger lines.
+    Drawing all lines for the whole score.
+
+    Version 2: QGraphicsItemGroup only vertical lines.
+    Only a few lines were created and were moved on scrolling.
+    QGraphicsItemGroupp.addToGroup and the constant updating was still too much.
+
+    Version 3: QGraphicsItem. Only vertical. Draw full scene. No scrolling trickery.
+    As simple as possible. Leave as much of the work to Qt.
+    We have a subitem that is actually the grid, so we can show/hide/delete that at once.
+
+    """
+
+    def __init__(self, parentScene):
+        super(GuiGrid, self).__init__()
+        self.parent = parentScene #QGraphicsScene
+        self.setFlag(QtWidgets.QGraphicsItem.ItemHasNoContents, True) #only child items. Without this we get notImplementedError: QGraphicsItem.paint() is abstract and must be overridden
+        self.setAcceptedMouseButtons(QtCore.Qt.NoButton)
+        self.setEnabled(False)
+        self.setOpacity(constantsAndConfigs.gridOpacity)
+        self.actualGridItem = None
+        self.nrOfVerticalLines = 0 #remember for optimisations
+        self._rememberSceneHeight = 0
+
+
+    def reactOnScoreChange(self):
+        """Entry point for callbacks and parent functions"""
+        self.redrawTickGrid()
+
+    def boundingRect(self):
+        return self.childrenBoundingRect()
+
+    def updateMode(self, nameAsString):
+        assert nameAsString in constantsAndConfigs.availableEditModes
+        if nameAsString == "block":
+            self.hide()
+        else:
+            self.show()
+
+    def redrawTickGrid(self):
+        """A complete redraw when triggered."""
+
+        gapVertical = constantsAndConfigs.gridRhythm / constantsAndConfigs.ticksToPixelRatio #this is necessary every time after stretching (ticksToPixelRatio) and after changing the gridRhythm
+        width = self.parent.maxTrackLength()
+        height = self.parent.cachedSceneHeight
+
+        lines = int(width / gapVertical) + 8 # + extra ones for a good feeling
+
+        if lines == self.nrOfVerticalLines and self._rememberSceneHeight == height:
+            return
+        else: #change
+            self.nrOfVerticalLines = lines
+            self._rememberSceneHeight = height
+
+        try:
+            self.parent.removeWhenIdle(self.actualGridItem) #remove all at once
+        except:
+            pass #will fail the first time on start
+
+        self.actualGridItem = ActualGrid(self)
+        self.actualGridItem.setFlag(QtWidgets.QGraphicsItem.ItemHasNoContents, True) #only child items. Without this we get notImplementedError: QGraphicsItem.paint() is abstract and must be overridden
+        self.actualGridItem.setParentItem(self)
+        self.actualGridItem.setPos(0,0)
+
+        for i in range(lines):
+            l = QtWidgets.QGraphicsLineItem(0,0,0, height, self.actualGridItem) #x1, y1, x2, y2, parent
+            l.setPos(i * gapVertical, 0)
+
+    def reactToresizeEventOrZoom(self):
+        """Called by the Views resizeEvent.
+        When the views geometry changes or zooms"""
+        pass
+
+    def stretchXCoordinates(self, factor):
+        """Reposition the items on the X axis.
+        Call goes through all parents/children, starting from ScoreView._stretchXCoordinates.
+        Docstring there."""
+        gapVertical = constantsAndConfigs.gridRhythm / constantsAndConfigs.ticksToPixelRatio #this is necessary every time after stretching (ticksToPixelRatio) and after changing the gridRhythm
+
+        for vline in self.actualGridItem.childItems(): #rhythm- and barlines
+            vline.setX(vline.x() * factor)
+
 
-class GuiGrid(QtWidgets.QGraphicsItemGroup):
+class OldGuiGrid(QtWidgets.QGraphicsItemGroup):
+    #Don't use that. QGraphicsItemGroup is very slow.
     """The grid consists of vertical lines.
     lines help to estimate
     the rhythm or tick positions e.g. when trying to find the right place for a tempo change or CC.
@@ -129,7 +223,7 @@ class GuiGrid(QtWidgets.QGraphicsItemGroup):
         """Only allowed to get called by reactToresizeEventOrZoom because we need an updated
         self.height value"""
         #Check if we need longer lines. Do this before creating new lines, because new lines
-        #have the heighest
+        #have the highest
         oldHeight = self.linesVertical[-1].line().y2() #this is a bit less than .length() so we use that
         if self.height > oldHeight:
             for vline in self.linesVertical:

qtgui/scorescene.py

@@ -70,12 +70,14 @@ class GuiScore(QtWidgets.QGraphicsScene):
         self.backColor.setNamedColor("#fdfdff")
         self.setBackgroundBrush(self.backColor)
 
+        self.cachedSceneHeight = 0 #set in self.redraw. Used by updateTrack to set the sceneRect
+
         self.grid = GuiGrid(parentScene=self)
         self.addItem(self.grid)
         self.grid.setPos(0, -20 * constantsAndConfigs.stafflineGap) #this is more calculation than simply using self.yStart, and might require manual adjustment in the future, but at least it guarantees the grid matches the staffline positions
         self.grid.setZValue(-50)
 
-        self.cachedSceneHeight = 0 #set in self.redraw. Used by updateTrack to set the sceneRect
+
 
         #All Cursors
         self.cursor = Cursor()
@@ -109,8 +111,8 @@ class GuiScore(QtWidgets.QGraphicsScene):
     def updateModeSingleTrackRedraw(self, nameAsString:str, trackId:int, trackExport:tuple):
         """trackExport is a tuple of block export dicts"""
         self.tracks[trackId].updateMode(nameAsString)
-        if nameAsString == "block":
-            self.tracks[trackId].stretchXCoordinates(0.25) #go into small scaling mode. 0.25 is hardcoded and the same as scoreView.updateMode
+        #if nameAsString == "block":
+        #    self.tracks[trackId].stretchXCoordinates(0.25) #go into small scaling mode. 0.25 is hardcoded and the same as scoreView.updateMode
 
     def maxTrackLength(self):
         if self.tracks:
@@ -129,6 +131,7 @@ class GuiScore(QtWidgets.QGraphicsScene):
             self.tracks[trackId].redraw(staticRepresentationList)
         #else:
             #hidden track. But this can still happen through the data editor
+        self.grid.reactOnScoreChange()
         self.updateSceneRect()
 
     def trackPaintBlockBackgroundColors(self, trackId, staticBlocksRepresentation):

qtgui/scoreview.py

@@ -139,7 +139,7 @@ class ScoreView(QtWidgets.QGraphicsView):
         function() #this is most likely an api function
 
     def resizeEvent(self, event):
-        """Triggers mostly when new notes are entered"""
+        """Triggers at least when the window is resized"""
         self.scoreScene.grid.reactToresizeEventOrZoom()
         super().resizeEvent(event)
 
@@ -200,8 +200,8 @@ class ScoreView(QtWidgets.QGraphicsView):
 
 
         if self.mainWindow.ui.actionCC_Mode.isChecked():
-            if calledByMenu and self._lastSavedMode == "block":
-                self.stretchXCoordinates(4.0) #return from half sized mode. If we do not come from block mode this is not needed. CC and Note mode have the same scaling
+            #if calledByMenu and self._lastSavedMode == "block":
+            #    self.stretchXCoordinates(4.0) #return from half sized mode. If we do not come from block mode this is not needed. CC and Note mode have the same scaling
 
             self.mainWindow.menuActionDatabase.ccEditMode()
             self.mainWindow.menuActionDatabase.writeProtection(True)
@@ -209,8 +209,8 @@ class ScoreView(QtWidgets.QGraphicsView):
             self.mainWindow.menuActionDatabase.loadToolbarContext("cc")
 
         elif self.mainWindow.ui.actionNotation_Mode.isChecked():
-            if calledByMenu and self._lastSavedMode == "block":
-                self.stretchXCoordinates(4.0) #return from half sized mode. If we do not come from block mode this is not needed. CC and Note mode have the same scaling
+            #if calledByMenu and self._lastSavedMode == "block":
+            #    self.stretchXCoordinates(4.0) #return from half sized mode. If we do not come from block mode this is not needed. CC and Note mode have the same scaling
 
             self.mainWindow.menuActionDatabase.noteEditMode()
             self.mainWindow.menuActionDatabase.writeProtection(False)
@@ -219,8 +219,8 @@ class ScoreView(QtWidgets.QGraphicsView):
 
         elif self.mainWindow.ui.actionBlock_Mode.isChecked():
             assert calledByMenu, "We currently assume that only the program start calls this function not via the menu, and that chooses notation mode"
-            if not self._lastSavedMode == "block": #check that we don't go from block mode to block mode again, since XScaling is cumulative
-                self.stretchXCoordinates(0.25) #go into small scaling mode. 0.25 is hardcoded and the same as scene.updateModeSingleTrackRedraw
+            #if not self._lastSavedMode == "block": #check that we don't go from block mode to block mode again, since XScaling is cumulative
+            #    self.stretchXCoordinates(0.25) #go into small scaling mode. 0.25 is hardcoded and the same as scene.updateModeSingleTrackRedraw
             self.mainWindow.menuActionDatabase.noteEditMode()
             self.mainWindow.menuActionDatabase.writeProtection(True)
             self.scoreScene.updateMode("block")