xref: /aosp_15_r20/external/fonttools/Lib/fontTools/subset/cff.py (revision e1fe3e4ad2793916b15cccdc4a7da52a7e1dd0e9)

from fontTools.misc import psCharStrings
from fontTools import ttLib
from fontTools.pens.basePen import NullPen
from fontTools.misc.roundTools import otRound
from fontTools.misc.loggingTools import deprecateFunction
from fontTools.subset.util import _add_method, _uniq_sort


class _ClosureGlyphsT2Decompiler(psCharStrings.SimpleT2Decompiler):
    def __init__(self, components, localSubrs, globalSubrs):
        psCharStrings.SimpleT2Decompiler.__init__(self, localSubrs, globalSubrs)
        self.components = components

    def op_endchar(self, index):
        args = self.popall()
        if len(args) >= 4:
            from fontTools.encodings.StandardEncoding import StandardEncoding

            # endchar can do seac accent bulding; The T2 spec says it's deprecated,
            # but recent software that shall remain nameless does output it.
            adx, ady, bchar, achar = args[-4:]
            baseGlyph = StandardEncoding[bchar]
            accentGlyph = StandardEncoding[achar]
            self.components.add(baseGlyph)
            self.components.add(accentGlyph)


@_add_method(ttLib.getTableClass("CFF "))
def closure_glyphs(self, s):
    cff = self.cff
    assert len(cff) == 1
    font = cff[cff.keys()[0]]
    glyphSet = font.CharStrings

    decompose = s.glyphs
    while decompose:
        components = set()
        for g in decompose:
            if g not in glyphSet:
                continue
            gl = glyphSet[g]

            subrs = getattr(gl.private, "Subrs", [])
            decompiler = _ClosureGlyphsT2Decompiler(components, subrs, gl.globalSubrs)
            decompiler.execute(gl)
        components -= s.glyphs
        s.glyphs.update(components)
        decompose = components


def _empty_charstring(font, glyphName, isCFF2, ignoreWidth=False):
    c, fdSelectIndex = font.CharStrings.getItemAndSelector(glyphName)
    if isCFF2 or ignoreWidth:
        # CFF2 charstrings have no widths nor 'endchar' operators
        c.setProgram([] if isCFF2 else ["endchar"])
    else:
        if hasattr(font, "FDArray") and font.FDArray is not None:
            private = font.FDArray[fdSelectIndex].Private
        else:
            private = font.Private
        dfltWdX = private.defaultWidthX
        nmnlWdX = private.nominalWidthX
        pen = NullPen()
        c.draw(pen)  # this will set the charstring's width
        if c.width != dfltWdX:
            c.program = [c.width - nmnlWdX, "endchar"]
        else:
            c.program = ["endchar"]


@_add_method(ttLib.getTableClass("CFF "))
def prune_pre_subset(self, font, options):
    cff = self.cff
    # CFF table must have one font only
    cff.fontNames = cff.fontNames[:1]

    if options.notdef_glyph and not options.notdef_outline:
        isCFF2 = cff.major > 1
        for fontname in cff.keys():
            font = cff[fontname]
            _empty_charstring(font, ".notdef", isCFF2=isCFF2)

    # Clear useless Encoding
    for fontname in cff.keys():
        font = cff[fontname]
        # https://github.com/fonttools/fonttools/issues/620
        font.Encoding = "StandardEncoding"

    return True  # bool(cff.fontNames)


@_add_method(ttLib.getTableClass("CFF "))
def subset_glyphs(self, s):
    cff = self.cff
    for fontname in cff.keys():
        font = cff[fontname]
        cs = font.CharStrings

        glyphs = s.glyphs.union(s.glyphs_emptied)

        # Load all glyphs
        for g in font.charset:
            if g not in glyphs:
                continue
            c, _ = cs.getItemAndSelector(g)

        if cs.charStringsAreIndexed:
            indices = [i for i, g in enumerate(font.charset) if g in glyphs]
            csi = cs.charStringsIndex
            csi.items = [csi.items[i] for i in indices]
            del csi.file, csi.offsets
            if hasattr(font, "FDSelect"):
                sel = font.FDSelect
                sel.format = None
                sel.gidArray = [sel.gidArray[i] for i in indices]
            newCharStrings = {}
            for indicesIdx, charsetIdx in enumerate(indices):
                g = font.charset[charsetIdx]
                if g in cs.charStrings:
                    newCharStrings[g] = indicesIdx
            cs.charStrings = newCharStrings
        else:
            cs.charStrings = {g: v for g, v in cs.charStrings.items() if g in glyphs}
        font.charset = [g for g in font.charset if g in glyphs]
        font.numGlyphs = len(font.charset)

        if s.options.retain_gids:
            isCFF2 = cff.major > 1
            for g in s.glyphs_emptied:
                _empty_charstring(font, g, isCFF2=isCFF2, ignoreWidth=True)

    return True  # any(cff[fontname].numGlyphs for fontname in cff.keys())


@_add_method(psCharStrings.T2CharString)
def subset_subroutines(self, subrs, gsubrs):
    p = self.program
    for i in range(1, len(p)):
        if p[i] == "callsubr":
            assert isinstance(p[i - 1], int)
            p[i - 1] = subrs._used.index(p[i - 1] + subrs._old_bias) - subrs._new_bias
        elif p[i] == "callgsubr":
            assert isinstance(p[i - 1], int)
            p[i - 1] = (
                gsubrs._used.index(p[i - 1] + gsubrs._old_bias) - gsubrs._new_bias
            )


@_add_method(psCharStrings.T2CharString)
def drop_hints(self):
    hints = self._hints

    if hints.deletions:
        p = self.program
        for idx in reversed(hints.deletions):
            del p[idx - 2 : idx]

    if hints.has_hint:
        assert not hints.deletions or hints.last_hint <= hints.deletions[0]
        self.program = self.program[hints.last_hint :]
        if not self.program:
            # TODO CFF2 no need for endchar.
            self.program.append("endchar")
        if hasattr(self, "width"):
            # Insert width back if needed
            if self.width != self.private.defaultWidthX:
                # For CFF2 charstrings, this should never happen
                assert (
                    self.private.defaultWidthX is not None
                ), "CFF2 CharStrings must not have an initial width value"
                self.program.insert(0, self.width - self.private.nominalWidthX)

    if hints.has_hintmask:
        i = 0
        p = self.program
        while i < len(p):
            if p[i] in ["hintmask", "cntrmask"]:
                assert i + 1 <= len(p)
                del p[i : i + 2]
                continue
            i += 1

    assert len(self.program)

    del self._hints


class _MarkingT2Decompiler(psCharStrings.SimpleT2Decompiler):
    def __init__(self, localSubrs, globalSubrs, private):
        psCharStrings.SimpleT2Decompiler.__init__(
            self, localSubrs, globalSubrs, private
        )
        for subrs in [localSubrs, globalSubrs]:
            if subrs and not hasattr(subrs, "_used"):
                subrs._used = set()

    def op_callsubr(self, index):
        self.localSubrs._used.add(self.operandStack[-1] + self.localBias)
        psCharStrings.SimpleT2Decompiler.op_callsubr(self, index)

    def op_callgsubr(self, index):
        self.globalSubrs._used.add(self.operandStack[-1] + self.globalBias)
        psCharStrings.SimpleT2Decompiler.op_callgsubr(self, index)


class _DehintingT2Decompiler(psCharStrings.T2WidthExtractor):
    class Hints(object):
        def __init__(self):
            # Whether calling this charstring produces any hint stems
            # Note that if a charstring starts with hintmask, it will
            # have has_hint set to True, because it *might* produce an
            # implicit vstem if called under certain conditions.
            self.has_hint = False
            # Index to start at to drop all hints
            self.last_hint = 0
            # Index up to which we know more hints are possible.
            # Only relevant if status is 0 or 1.
            self.last_checked = 0
            # The status means:
            # 0: after dropping hints, this charstring is empty
            # 1: after dropping hints, there may be more hints
            # 	continuing after this, or there might be
            # 	other things.  Not clear yet.
            # 2: no more hints possible after this charstring
            self.status = 0
            # Has hintmask instructions; not recursive
            self.has_hintmask = False
            # List of indices of calls to empty subroutines to remove.
            self.deletions = []

        pass

    def __init__(
        self, css, localSubrs, globalSubrs, nominalWidthX, defaultWidthX, private=None
    ):
        self._css = css
        psCharStrings.T2WidthExtractor.__init__(
            self, localSubrs, globalSubrs, nominalWidthX, defaultWidthX
        )
        self.private = private

    def execute(self, charString):
        old_hints = charString._hints if hasattr(charString, "_hints") else None
        charString._hints = self.Hints()

        psCharStrings.T2WidthExtractor.execute(self, charString)

        hints = charString._hints

        if hints.has_hint or hints.has_hintmask:
            self._css.add(charString)

        if hints.status != 2:
            # Check from last_check, make sure we didn't have any operators.
            for i in range(hints.last_checked, len(charString.program) - 1):
                if isinstance(charString.program[i], str):
                    hints.status = 2
                    break
                else:
                    hints.status = 1  # There's *something* here
            hints.last_checked = len(charString.program)

        if old_hints:
            assert hints.__dict__ == old_hints.__dict__

    def op_callsubr(self, index):
        subr = self.localSubrs[self.operandStack[-1] + self.localBias]
        psCharStrings.T2WidthExtractor.op_callsubr(self, index)
        self.processSubr(index, subr)

    def op_callgsubr(self, index):
        subr = self.globalSubrs[self.operandStack[-1] + self.globalBias]
        psCharStrings.T2WidthExtractor.op_callgsubr(self, index)
        self.processSubr(index, subr)

    def op_hstem(self, index):
        psCharStrings.T2WidthExtractor.op_hstem(self, index)
        self.processHint(index)

    def op_vstem(self, index):
        psCharStrings.T2WidthExtractor.op_vstem(self, index)
        self.processHint(index)

    def op_hstemhm(self, index):
        psCharStrings.T2WidthExtractor.op_hstemhm(self, index)
        self.processHint(index)

    def op_vstemhm(self, index):
        psCharStrings.T2WidthExtractor.op_vstemhm(self, index)
        self.processHint(index)

    def op_hintmask(self, index):
        rv = psCharStrings.T2WidthExtractor.op_hintmask(self, index)
        self.processHintmask(index)
        return rv

    def op_cntrmask(self, index):
        rv = psCharStrings.T2WidthExtractor.op_cntrmask(self, index)
        self.processHintmask(index)
        return rv

    def processHintmask(self, index):
        cs = self.callingStack[-1]
        hints = cs._hints
        hints.has_hintmask = True
        if hints.status != 2:
            # Check from last_check, see if we may be an implicit vstem
            for i in range(hints.last_checked, index - 1):
                if isinstance(cs.program[i], str):
                    hints.status = 2
                    break
            else:
                # We are an implicit vstem
                hints.has_hint = True
                hints.last_hint = index + 1
                hints.status = 0
        hints.last_checked = index + 1

    def processHint(self, index):
        cs = self.callingStack[-1]
        hints = cs._hints
        hints.has_hint = True
        hints.last_hint = index
        hints.last_checked = index

    def processSubr(self, index, subr):
        cs = self.callingStack[-1]
        hints = cs._hints
        subr_hints = subr._hints

        # Check from last_check, make sure we didn't have
        # any operators.
        if hints.status != 2:
            for i in range(hints.last_checked, index - 1):
                if isinstance(cs.program[i], str):
                    hints.status = 2
                    break
            hints.last_checked = index

        if hints.status != 2:
            if subr_hints.has_hint:
                hints.has_hint = True

                # Decide where to chop off from
                if subr_hints.status == 0:
                    hints.last_hint = index
                else:
                    hints.last_hint = index - 2  # Leave the subr call in

        elif subr_hints.status == 0:
            hints.deletions.append(index)

        hints.status = max(hints.status, subr_hints.status)


@_add_method(ttLib.getTableClass("CFF "))
def prune_post_subset(self, ttfFont, options):
    cff = self.cff
    for fontname in cff.keys():
        font = cff[fontname]
        cs = font.CharStrings

        # Drop unused FontDictionaries
        if hasattr(font, "FDSelect"):
            sel = font.FDSelect
            indices = _uniq_sort(sel.gidArray)
            sel.gidArray = [indices.index(ss) for ss in sel.gidArray]
            arr = font.FDArray
            arr.items = [arr[i] for i in indices]
            del arr.file, arr.offsets

    # Desubroutinize if asked for
    if options.desubroutinize:
        cff.desubroutinize()

    # Drop hints if not needed
    if not options.hinting:
        self.remove_hints()
    elif not options.desubroutinize:
        self.remove_unused_subroutines()
    return True


def _delete_empty_subrs(private_dict):
    if hasattr(private_dict, "Subrs") and not private_dict.Subrs:
        if "Subrs" in private_dict.rawDict:
            del private_dict.rawDict["Subrs"]
        del private_dict.Subrs


@deprecateFunction(
    "use 'CFFFontSet.desubroutinize()' instead", category=DeprecationWarning
)
@_add_method(ttLib.getTableClass("CFF "))
def desubroutinize(self):
    self.cff.desubroutinize()


@_add_method(ttLib.getTableClass("CFF "))
def remove_hints(self):
    cff = self.cff
    for fontname in cff.keys():
        font = cff[fontname]
        cs = font.CharStrings
        # This can be tricky, but doesn't have to. What we do is:
        #
        # - Run all used glyph charstrings and recurse into subroutines,
        # - For each charstring (including subroutines), if it has any
        #   of the hint stem operators, we mark it as such.
        #   Upon returning, for each charstring we note all the
        #   subroutine calls it makes that (recursively) contain a stem,
        # - Dropping hinting then consists of the following two ops:
        #   * Drop the piece of the program in each charstring before the
        #     last call to a stem op or a stem-calling subroutine,
        #   * Drop all hintmask operations.
        # - It's trickier... A hintmask right after hints and a few numbers
        #    will act as an implicit vstemhm. As such, we track whether
        #    we have seen any non-hint operators so far and do the right
        #    thing, recursively... Good luck understanding that :(
        css = set()
        for g in font.charset:
            c, _ = cs.getItemAndSelector(g)
            c.decompile()
            subrs = getattr(c.private, "Subrs", [])
            decompiler = _DehintingT2Decompiler(
                css,
                subrs,
                c.globalSubrs,
                c.private.nominalWidthX,
                c.private.defaultWidthX,
                c.private,
            )
            decompiler.execute(c)
            c.width = decompiler.width
        for charstring in css:
            charstring.drop_hints()
        del css

        # Drop font-wide hinting values
        all_privs = []
        if hasattr(font, "FDArray"):
            all_privs.extend(fd.Private for fd in font.FDArray)
        else:
            all_privs.append(font.Private)
        for priv in all_privs:
            for k in [
                "BlueValues",
                "OtherBlues",
                "FamilyBlues",
                "FamilyOtherBlues",
                "BlueScale",
                "BlueShift",
                "BlueFuzz",
                "StemSnapH",
                "StemSnapV",
                "StdHW",
                "StdVW",
                "ForceBold",
                "LanguageGroup",
                "ExpansionFactor",
            ]:
                if hasattr(priv, k):
                    setattr(priv, k, None)
    self.remove_unused_subroutines()


@_add_method(ttLib.getTableClass("CFF "))
def remove_unused_subroutines(self):
    cff = self.cff
    for fontname in cff.keys():
        font = cff[fontname]
        cs = font.CharStrings
        # Renumber subroutines to remove unused ones

        # Mark all used subroutines
        for g in font.charset:
            c, _ = cs.getItemAndSelector(g)
            subrs = getattr(c.private, "Subrs", [])
            decompiler = _MarkingT2Decompiler(subrs, c.globalSubrs, c.private)
            decompiler.execute(c)

        all_subrs = [font.GlobalSubrs]
        if hasattr(font, "FDArray"):
            all_subrs.extend(
                fd.Private.Subrs
                for fd in font.FDArray
                if hasattr(fd.Private, "Subrs") and fd.Private.Subrs
            )
        elif hasattr(font.Private, "Subrs") and font.Private.Subrs:
            all_subrs.append(font.Private.Subrs)

        subrs = set(subrs)  # Remove duplicates

        # Prepare
        for subrs in all_subrs:
            if not hasattr(subrs, "_used"):
                subrs._used = set()
            subrs._used = _uniq_sort(subrs._used)
            subrs._old_bias = psCharStrings.calcSubrBias(subrs)
            subrs._new_bias = psCharStrings.calcSubrBias(subrs._used)

        # Renumber glyph charstrings
        for g in font.charset:
            c, _ = cs.getItemAndSelector(g)
            subrs = getattr(c.private, "Subrs", None)
            c.subset_subroutines(subrs, font.GlobalSubrs)

        # Renumber subroutines themselves
        for subrs in all_subrs:
            if subrs == font.GlobalSubrs:
                if not hasattr(font, "FDArray") and hasattr(font.Private, "Subrs"):
                    local_subrs = font.Private.Subrs
                else:
                    local_subrs = None
            else:
                local_subrs = subrs

            subrs.items = [subrs.items[i] for i in subrs._used]
            if hasattr(subrs, "file"):
                del subrs.file
            if hasattr(subrs, "offsets"):
                del subrs.offsets

            for subr in subrs.items:
                subr.subset_subroutines(local_subrs, font.GlobalSubrs)

        # Delete local SubrsIndex if empty
        if hasattr(font, "FDArray"):
            for fd in font.FDArray:
                _delete_empty_subrs(fd.Private)
        else:
            _delete_empty_subrs(font.Private)

        # Cleanup
        for subrs in all_subrs:
            del subrs._used, subrs._old_bias, subrs._new_bias