change color of block labels according to background

CHANGELOG

@@ -11,6 +11,7 @@ Add midi-in selector drop down, as seen in Tembro and Fluajho.
 Rewrite grid, which was a performance drag in the past.
 Add functions to move block to start or end of track.
 Scroll view when dragging blocks and tracks with the mouse.
+Block name font color is now always readable, no matter the background color
 Add 3/2 to metrical instruction.
 Autosave when exporting Lilypond .ly or PDF.
 Command to quickly add text below or above a staff.

qtgui/musicstructures.py

@@ -58,7 +58,6 @@ class GuiBlockHandle(QtWidgets.QGraphicsRectItem):
         #self.setFlag(QtWidgets.QGraphicsItem.ItemContainsChildrenInShape, True)
         self.parent = parent #GuiTrack instance
         self.parentGuiTrack = parent #redundant, but specifically for block movement. see ScoreScene
-        self.color = None #QColor inserted by the creating function in GuiTrack. Used during dragging, then reset to transparent.
         self.trans = QtGui.QColor("transparent")
         self.setPen(self.trans)
         self.setBrush(self.trans)
@@ -68,7 +67,7 @@ class GuiBlockHandle(QtWidgets.QGraphicsRectItem):
         self.setParentItem(parent)
         self.setZValue(10) #This is the z value within GuiTrack
         self.staticExportItem = staticExportItem
-
+        self._color = None # @property
         self.posBeforeMove = None
         self.cursorPosOnMoveStart = None
 
@@ -99,6 +98,25 @@ class GuiBlockHandle(QtWidgets.QGraphicsRectItem):
         self.endLabel.setPos(self.rect().width() - self.endLabel.boundingRect().width(), constantsAndConfigs.stafflineGap)
         self.endLabel.setFlags(QtWidgets.QGraphicsItem.ItemIgnoresParentOpacity)
 
+    @property
+    def color(self):
+        assert self._color
+        return self._color
+
+    @color.setter
+    def color(self, c:QtGui.QColor):
+        """QColor inserted by the creating function in GuiTrack.
+        Only available during mousePressEvent. Used during dragging, then reset to transparent.
+
+        This is on every change. Every note."""
+        self._color = c
+        if c.lightness() > 127: #between 0 (for black) and 255 (for white)
+            labelColor = QtGui.QColor("black")
+        else:
+            labelColor = QtGui.QColor("white")
+        self.startLabel.setBrush(labelColor)
+        self.endLabel.setBrush(labelColor)
+
     def stretchXCoordinates(self, factor):
         """Reposition the items on the X axis.
         Call goes through all parents/children, starting from ScoreView._stretchXCoordinates.
@@ -114,6 +132,7 @@ class GuiBlockHandle(QtWidgets.QGraphicsRectItem):
         self.startLabel.hide()
         self.endLabel.hide()
 
+
     def mousePressEventCustom(self, event):
         """Not a qt-override. This is called directly by GuiScore
         if you click on a block with the right modifier keys (none)"""
@@ -143,8 +162,6 @@ class GuiBlockHandle(QtWidgets.QGraphicsRectItem):
          We do not use event parameter. This is for compatibility.
          """
         if self.startLabel.isVisible(): #block mode
-            print (self.staticExportItem["name"], event)
-
             listOfLabelsAndFunctions = [
                 (translate("musicstructures", "edit properties"), lambda: BlockPropertiesEdit(self.scene().parentView.mainWindow, staticExportItem = self.staticExportItem)),
                 ("separator", None),