Flipped glyph preview in Robofont

flipped_preview.py

from mojo.events import BaseEventTool, addObserver
from AppKit import NSColor
from fontTools.pens.basePen import BasePen
from fontTools.pens.cocoaPen import CocoaPen


class CocoaGlyphPen(BasePen):

    def __init__(self, onCurveSize, offCurveSize, selection=[]):
        self.glyphPen = CocoaPen(None)
        self.glyphPath = self.glyphPen.path
        self.onCurvePen = CocoaPen(None)
        self.onCurvePoints = self.onCurvePen.path
        self.offCurvePen = CocoaPen(None)
        self.offCurvePoints = self.offCurvePen.path
        self.handleLinePen = CocoaPen(None)
        self.handleLines = self.handleLinePen.path
        self.selectedPen = CocoaPen(None)
        self.selectedPoints = self.selectedPen.path
        self.onCurveSize = onCurveSize
        self.offCurveSize = offCurveSize
        self.selection = selection

    def _moveTo(self, pt):
        self.glyphPen.moveTo(pt)
        self.drawOnCurve(pt)
        self.previousPoint = pt

    def _lineTo(self, pt):
        self.glyphPen.lineTo(pt)
        self.drawOnCurve(pt)
        self.previousPoint = pt

    def _curveToOne(self, pt1, pt2, pt3):
        self.glyphPen.curveTo(pt1, pt2, pt3)
        self.drawOffCurve(pt1)
        self.drawOffCurve(pt2)
        self.drawHandleLine(pt1, self.previousPoint)
        self.drawHandleLine(pt2, pt3)
        self.drawOnCurve(pt3)
        self.previousPoint = pt3

    def endPath(self):
        self.glyphPen.endPath()

    def closePath(self):
        self.glyphPen.closePath()

    def addComponent(self, baseName, transform):
        pass

    def drawOnCurve(self, pt, selection=False):
        if pt in self.selection:
            cocoaPen = self.selectedPen
        else:
            cocoaPen = self.onCurvePen
        size = self.onCurveSize
        x, y = pt
        cocoaPen.moveTo((x - size, y - size))
        cocoaPen.lineTo((x + size, y - size))
        cocoaPen.lineTo((x + size, y + size))
        cocoaPen.lineTo((x - size, y + size))
        cocoaPen.lineTo((x - size, y - size))
        cocoaPen.closePath()

    def drawOffCurve(self, pt, selection=False):
        if pt in self.selection:
            cocoaPen = self.selectedPen
        else:
            cocoaPen = self.offCurvePen
        size = self.offCurveSize
        x, y = pt
        cocoaPen.moveTo((x, y - size))
        cocoaPen.lineTo((x + size, y))
        cocoaPen.lineTo((x, y + size))
        cocoaPen.lineTo((x - size, y))
        cocoaPen.lineTo((x, y - size))
        cocoaPen.closePath()
        cocoaPen.closePath()

    def drawHandleLine(self, pt1, pt2):
        cocoaPen = self.handleLinePen
        x, y = pt1
        xa, ya = pt2
        cocoaPen.moveTo((xa, ya))
        cocoaPen.lineTo((x, y))


class PreviewFlipped(BaseEventTool):
    def __init__(self, *args, **kwargs):
        self.previewGlyph = None
        addObserver(self, 'previewSolid', 'drawPreview')

    def flip_glyph(self, glyph):
        rg = RGlyph()
        if glyph.contours:
            for c in glyph.contours:
                rg.appendContour(c)
            rg.width = glyph.width
            center_x = rg.box[0] + (rg.box[2] - rg.box[0]) / 2
            center_y = rg.box[1] + (rg.box[3] - rg.box[1]) / 2
            for c in rg.contours:
                c.scale((-1, -1), (center_x, center_y))
                c.move((rg.width, 0))
            return rg
        return

    def drawPreview(self, glyph):
        # scale = 1
        previewPen = CocoaGlyphPen(0, 0)
        glyph.draw(previewPen)

        fillColor = NSColor.colorWithCalibratedRed_green_blue_alpha_(
            0, 0, 0, 1)
        fillColor.set()
        previewPen.glyphPath.fill()

    def previewSolid(self, sender):
        g = sender['glyph']
        if g.contours:
            self.previewGlyph = self.flip_glyph(g)
            self.drawPreview(self.previewGlyph)


PreviewFlipped()