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.UI import getDefault, setDefault, inDarkMode
from lib.tools.notifications import PostNotification
from fontTools.pens.basePen import BasePen
from mojo.subscriber import Subscriber, registerGlyphEditorSubscriber, unregisterGlyphEditorSubscriber, listRegisteredSubscribers


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 = False
    if inDarkMode():
        suff = ".dark"
    else:
        suff = ""

    def build(self):
        glyphEditor = self.getGlyphEditor()
        self.container = glyphEditor.extensionContainer(
            identifier='com.roboFont.removeOverlapPreview.background',
            location='background',
            clear=True,
        )
                
        self.strokeColor = tuple(float(a) for a in getDefault(f'glyphViewStrokeColor{self.suff}'))
        self.compStrokeColor = tuple(float(a) for a in getDefault(f'glyphViewComponentStrokeColor{self.suff}'))
        
        self.pathLayer = self.container.appendPathSublayer(
            strokeColor=None,
            fillColor=None,
            strokeWidth=getDefault(f'glyphViewStrokeWidth'),
            )

        self.setView()

    def resetDefaults(self):
        setDefault(f'glyphViewComponentStrokeColor{self.suff}', self.compStrokeColor)
        setDefault(f'glyphViewStrokeColor{self.suff}', self.strokeColor)
        PostNotification('doodle.preferencesChanged')

    def setView(self):
        opacity = .3
        setDefault(f'glyphViewComponentStrokeColor{self.suff}', tuple((self.compStrokeColor[0], self.compStrokeColor[1], self.compStrokeColor[2], opacity)))
        setDefault(f'glyphViewStrokeColor{self.suff}', tuple((self.strokeColor[0], self.strokeColor[1], self.strokeColor[2], opacity)))
        PostNotification('doodle.preferencesChanged')

    def destroy(self):
        self.container.clearSublayers()
        self.resetDefaults()

    def glyphEditorDidSetGlyph(self, info):
        glyph = info['glyph']
        if glyph is not None:
            self.nooverlap(glyph)

    def glyphEditorGlyphDidChange(self, info):
        glyph = info['glyph']
        if glyph is not None:
            self.nooverlap(glyph)
        
    def glyphEditorDidMouseDrag(self, info):
        glyph = info['glyph']
        if glyph is not None:
            self.nooverlap(glyph)

    def nooverlap(self, glyph):
        self.pathLayer.clearSublayers()
        tempGlyph = RGlyph()
        pen = MyCopyDecomposingPen(glyph.font, tempGlyph.getPen())
        glyph.draw(pen)
        tempGlyph.removeOverlap(round=1)
        glyphPath = tempGlyph.getRepresentation("merz.CGPath")
        self.pathLayer.setPath(glyphPath)
        if not glyph.contours:
            strokeColor = self.compStrokeColor
        else:
            strokeColor = self.strokeColor
        self.pathLayer.setStrokeColor(strokeColor)
        

if __name__ == '__main__':
    
    finder = [subs for subs in listRegisteredSubscribers() if 'removeOverlapPreview' in subs.getIdentifier()]
    if finder:        
        for s in finder:
            unregisterGlyphEditorSubscriber(s)
            print("uninstall")
    else:
        registerGlyphEditorSubscriber(removeOverlapPreview)
        print("install")