A startup script to preview a glyph with no overlap. Idea stolen from Glyphs (I still hate Glyphs)

removeOverlapPreview.py

from mojo.roboFont import RGlyph
from mojo.subscriber import Subscriber, registerGlyphEditorSubscriber
from mojo.UI import getDefault, setDefault
from lib.tools.notifications import PostNotification
from fontTools.pens.basePen import BasePen


class MyCopyDecomposingPen(BasePen):
    def __init__(self, glyphSet, outPen):
        super(MyCopyDecomposingPen, self).__init__(glyphSet)
        self._moveTo = outPen.moveTo
        self._lineTo = outPen.lineTo
        self._curveToOne = outPen.curveTo
        self._closePath = outPen.closePath
        self._endPath = outPen.endPath


class removeOverlapPreview(Subscriber):

    debug = True
    toggle = False

    def build(self):
        self.name = self.__class__.__name__
        if self.debug == True:
            print(self.name, 'build!')
        glyphEditor = self.getGlyphEditor()
        self.backgroundContainer = glyphEditor.extensionContainer(
            identifier='com.roboFont.removeOverlapPreview.background',
            location='background',
            clear=True
        )
        self.strokeColor = tuple(float(a) for a in getDefault('glyphViewStrokeColor'))
        self.compStrokeColor = tuple(float(a) for a in getDefault('glyphViewComponentStrokeColor'))

    def destroy(self):
        if self.debug == True:
            print(self.name, 'destroy!')
            self.clearView()

    def setView(self):
        opacity = .2
        setDefault('glyphViewComponentStrokeColor', tuple((self.compStrokeColor[0], self.compStrokeColor[1], self.compStrokeColor[2], opacity)))
        setDefault('glyphViewStrokeColor', tuple((self.strokeColor[0], self.strokeColor[1], self.strokeColor[2], opacity)))
        PostNotification('doodle.preferencesChanged')

    def clearView(self):
        self.backgroundContainer.clearSublayers()
        setDefault('glyphViewComponentStrokeColor', self.compStrokeColor)
        setDefault('glyphViewStrokeColor', self.strokeColor)
        PostNotification('doodle.preferencesChanged')

    def glyphEditorKeyDown(self, info):
        glyph = info['glyph']
        characters = info['lowLevelEvents'][0]['event'].characters()
        if characters == '~':
            self.toggle = not self.toggle
        self.nooverlap(glyph)

    def glyphEditorDidSetGlyph(self, info):
        glyph = info['glyph']
        self.nooverlap(glyph)

    def glyphDidChange(self, info):
        glyph = info['glyph']
        self.nooverlap(glyph)

    def nooverlap(self, glyph):
        if self.toggle == False:
            self.clearView()
        else:
            self.setView()
            nooverlapLayer = self.backgroundContainer.getSublayer('nooverlap')
            if nooverlapLayer is not None:
                nooverlapLayer.clearSublayers()
            else:
                nooverlapLayer = self.backgroundContainer.appendBaseSublayer(
                    name='nooverlap'
                )
            tempGlyph = RGlyph()
            pen = MyCopyDecomposingPen(glyph.font, tempGlyph.getPen())
            glyph.draw(pen)
            tempGlyph.removeOverlap(round=1)
            with nooverlapLayer.drawingTools() as bot:
                bot.fill(None)
                bot.strokeWidth((getDefault('glyphViewStrokeWidth')))
                bot.stroke(*self.strokeColor)
                bot.drawGlyph(tempGlyph)


registerGlyphEditorSubscriber(removeOverlapPreview)