A script to make all glyphs in a TTF blank, while leaving metrics, features, etc in place.

make-blank-glyphs-in-ttf.py

"""
    A script to make all glyphs in a TTF blank, while leaving metrics, features, etc in place.
"""

from fontTools import ttLib
from fontTools.ttLib.tables._g_l_y_f import Glyph
from argparse import ArgumentParser


def eraseGlyphs(fontPath, inplace=False):

    # open font to edit as TTFont object
    font = ttLib.TTFont(fontPath)

    for glyphName in font.getGlyphNames():

        # check if the glyph is composite, and set it to an empty glyph object if not
        # credit to @_justinpenner and @jenskutilek for pointing this out
        if not font['glyf'][glyphName].isComposite():
            font['glyf'][glyphName] = Glyph()

        ## Alternatively, you could make a blank shape in a pen, then set the glyph to that blank path.
        ## It’s not as good a solution as above, but I’m leaving it here for potential future reference. :D
        # from fontTools.pens.ttGlyphPen import TTGlyphPen      # move this to the top, obviously
        # pen = TTGlyphPen(None)                                # make a new pen
        # pen.lineTo((0,0))                                     # set up a single point
        # pen.closePath()                                       # close path
        # font['glyf'][glyphName] = pen.glyph()                 # set glyph to the shape

    # if the font is variable, delete the gvar table because it’s no longer needed, and deleting it will reduce font data by a lot
    if 'gvar' in font:
        del font['gvar']

    # save font
    if inplace:
        font.save(fontPath)
        print("\nGlyphs are now blank.\n")
    else:
        newPath = fontPath.replace('.ttf','.blank.ttf')
        font.save(newPath)
        print("Saved font with blank glyphs at ", newPath)

def main():
    description = "Make all glyphs in a TTF blank, while leaving metrics, features, etc in place."
    parser = ArgumentParser(description=description)
    parser.add_argument('font', nargs=1)
    parser.add_argument('--inplace', action='store_true')
    args = parser.parse_args()

    eraseGlyphs(args.font[0], args.inplace)


if __name__ == '__main__':
    main()