RoboFont script to fix contour direction for postscript curves (CFF/Cubic/OTF) on selected glyphs.

Fix Contour Directions.py

"""
RoboFont Script
based on:
https://gist.github.com/ryanbugden/a4ddf19cab034f837a51fb9d4f0db015

- Type: Mastering
- Purpose: To fix contour direction for postscript curves (CFF/Cubic/OTF) in selected glyphs.
- Specifications:
    - Sorts contours by area and clusters them into contours that contain other contours
    - Reverses the direction of contours in clusters where the largest contour is not clockwise
- Publish Date: 2024-11-08
- Author: Bahman Eskami
- License: MIT
"""

def fix_contour_direction(g):
    """
    Fixes the contour direction for postscript curves (CFF/Cubic/OTF) in a given glyph.

    Args:
        g (fontParts.RGlyph): The glyph to fix contour direction for.

    Returns:
        bool: True if any contours were reversed, False otherwise.
    """
    contours = list(sorted(g.contours, key=lambda c: -c.area)) # bigger contours first

    clusters = [] # cluster are made of contours that contain other contours
    for contour in contours:
        added = False
        for cluster in clusters:
            for c in cluster:
                if c.contourInside(contour):
                    # add the hole as part of the cluster
                    cluster.append(contour)
                    added = True
                    break
        if not added:
            clusters.append([contour, ])

    changed = False
    for contour_list in clusters:
        if contour_list[0].clockwise:
            for c in contour_list:
                c.reverse()
                changed = True
    return changed

if __name__ == '__main__':
    import fontgadgets.extensions.robofont.UI # requires fontgadgets extension
    from mojo.UI import limitFontViewToGlyphSet
    from mojo.UI import CurrentSelectedGlyphNames

    for f in AllFonts():
        gs = CurrentSelectedGlyphNames()
        lv = set()
        for gn in gs:
            g = f[gn]
            with g.undo():
                if fix_contour_direction(g):
                    lv.add(gn)

    limitFontViewToGlyphSet(lv)