Check coordinates in font glyphs vs. x and y Min + Max value definitions defined in the glyph header (glyf table)

glyph-coord-check.py

#!/usr/bin/env python3

# ---------------------------------------------------------------------------
# Copyright 2019 Christopher Simpkins
# Apache License, v2.0
#
# Portions of this source file are derived from the
#
#    `com.google.fonts/check/points_out_of_bounds`
#
# check in the Font Bakery project (https://github.com/googlefonts/fontbakery/)
# and used under the Apache License, v2.0
# -----------------------------------------------------------------------------

import os
import sys

from fontTools.ttLib import TTFont


def main(argv):
    for fontpath in argv:
        if not os.path.isfile(fontpath):
            sys.stderr.write(
                f"[ERROR] {fontpath} does not appear to be a path to a valid font file"
            )
            sys.exit(1)

        tt = TTFont(fontpath)
        glyf_table = tt["glyf"]
        coord_bounds_error_list = []
        for gname in glyf_table.keys():
            glyph = tt["glyf"][gname]
            coords = glyph.getCoordinates(glyf_table)[0]
            message = ""
            # derived from the tests performed in the Fontbakery
            # com.google.fonts/check/points_out_of_bounds check
            for x, y in coords:
                if round(x) < glyph.xMin:
                    message = f"(comp: {glyph.isComposite()}) x value {x} < glyph xMin value {glyph.xMin} @ point ({x}, {y})"
                    coord_bounds_error_list.append((gname, x, y, message))
                elif round(x) > glyph.xMax:
                    message = f"(comp: {glyph.isComposite()}) x value {x} > glyph xMax value {glyph.xMax} @ point ({x}, {y})"
                    coord_bounds_error_list.append((gname, x, y, message))
                elif round(y) < glyph.yMin:
                    message = f"(comp: {glyph.isComposite()}) y value {y} < glyph yMin value {glyph.yMin} @ point ({x}, {y})"
                    coord_bounds_error_list.append((gname, x, y, message))
                elif round(y) > glyph.yMax:
                    message = f"(comp: {glyph.isComposite()}) y value {y} > glyph yMax value {glyph.yMax} @ point ({x}, {y})"
                    coord_bounds_error_list.append((gname, x, y, message))
                elif abs(x) > 32766:
                    message = f"(comp: {glyph.isComposite()}) x value {x} > 32766 @ point ({x}, {y})"
                    coord_bounds_error_list.append((gname, x, y, message))
                elif abs(y) > 32766:
                    message = f"(comp: {glyph.isComposite()}) y value {y} > 32766 @ point ({x}, {y})"
                    coord_bounds_error_list.append((gname, x, y, message))
                else:
                    pass

        if len(coord_bounds_error_list) == 0:
            print(f"[OK] No errors identified in '{fontpath}'")
        else:
            print(f"[RESULT] '{fontpath}'")
            for err in coord_bounds_error_list:
                # print glyph name and error message
                print(f"{err[0]}: {err[3]}")

            print(f"[END RESULT] '{fontpath}'\n")


if __name__ == "__main__":
    main(sys.argv[1:])