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| # Modified from https://github.com/adobe-type-tools/psautohint/blob/08b346865710ed3c172f1eb581d6ef243b203f99/python/psautohint/ufoFont.py#L800-L838 | |
| import hashlib | |
| from fontTools.pens.basePen import MissingComponentError | |
| from fontTools.pens.pointPen import AbstractPointPen | |
| class HashPointPen(AbstractPointPen): | |
| """ | |
| This pen can be used to check if a glyph's contents (outlines plus | |
| components) have changed. | |
| Components are added as the original outline plus each composite's | |
| transformation. | |
| Example: You have some TrueType hinting code for a glyph which you want to | |
| compile. The hinting code specifies a hash value computed with HashPointPen | |
| that was valid for the glyph's outlines at the time the hinting code was | |
| written. Now you can calculate the hash for the glyph's current outlines to | |
| check if the outlines have changed, which would probably make the hinting | |
| code invalid. | |
| > glyph = ufo[name] | |
| > hash_pen = HashPointPen(glyph.width, ufo) | |
| > glyph.drawPoints(hash_pen) | |
| > ttdata = glyph.lib.get("public.truetype.instructions", None) | |
| > stored_hash = ttdata.get("id", None) # The hash is stored in the "id" key | |
| > if stored_hash is None or stored_hash != hash_pen.hash: | |
| > logger.error(f"Glyph hash mismatch, glyph '{name}' will have no instructions in font.") | |
| > else: | |
| > # The hash values are identical, the outline has not changed. | |
| > # Compile the hinting code ... | |
| > pass | |
| If you want to compare a glyph from a source format which supports floating point | |
| coordinates and transformations against a glyph from a format which has restrictions | |
| on the precision of floats, e.g. UFO vs. TTF, you must use an appropriate rounding | |
| function to make the values comparable. For TTF fonts with composites, this | |
| construct can be used to make the transform values conform to F2Dot14: | |
| > ttf_hash_pen = HashPointPen(ttf_glyph_width, ttFont.getGlyphSet()) | |
| > ttf_round_pen = RoundingPointPen(ttf_hash_pen, transformRoundFunc=partial(floatToFixedToFloat, precisionBits=14)) | |
| > ufo_hash_pen = HashPointPen(ufo_glyph.width, ufo) | |
| > ttf_glyph.drawPoints(ttf_round_pen, ttFont["glyf"]) | |
| > ufo_round_pen = RoundingPointPen(ufo_hash_pen, transformRoundFunc=partial(floatToFixedToFloat, precisionBits=14)) | |
| > ufo_glyph.drawPoints(ufo_round_pen) | |
| > assert ttf_hash_pen.hash == ufo_hash_pen.hash | |
| """ | |
| def __init__(self, glyphWidth=0, glyphSet=None): | |
| self.glyphset = glyphSet | |
| self.data = ["w%s" % round(glyphWidth, 9)] | |
| def hash(self): | |
| data = "".join(self.data) | |
| if len(data) >= 128: | |
| data = hashlib.sha512(data.encode("ascii")).hexdigest() | |
| return data | |
| def beginPath(self, identifier=None, **kwargs): | |
| pass | |
| def endPath(self): | |
| self.data.append("|") | |
| def addPoint( | |
| self, | |
| pt, | |
| segmentType=None, | |
| smooth=False, | |
| name=None, | |
| identifier=None, | |
| **kwargs, | |
| ): | |
| if segmentType is None: | |
| pt_type = "o" # offcurve | |
| else: | |
| pt_type = segmentType[0] | |
| self.data.append(f"{pt_type}{pt[0]:g}{pt[1]:+g}") | |
| def addComponent(self, baseGlyphName, transformation, identifier=None, **kwargs): | |
| tr = "".join([f"{t:+}" for t in transformation]) | |
| self.data.append("[") | |
| try: | |
| self.glyphset[baseGlyphName].drawPoints(self) | |
| except KeyError: | |
| raise MissingComponentError(baseGlyphName) | |
| self.data.append(f"({tr})]") | |