[AAT] Implement anchor point table
The AAT `ankr` anchor point table is an auxiliary table for `kerx`, used to store anchor overrides in case the glyph itself does not supply the needed anchors as control points. Among the fonts that come pre-installed with MacOS 10.12.6, `ankr` is used by a handful of non-Latin fonts such as “Myanmar MN”, “Devanagari Sangam MN”, and “Arial HB”. https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6ankr.html
This commit is contained in:
Sascha Brawer
parent
90f257cc60
commit
92124ee5a6
@ -50,6 +50,7 @@ def _moduleFinderHint():
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from . import V_D_M_X_
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from . import V_O_R_G_
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from . import V_V_A_R_
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from . import _a_n_k_r
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from . import _a_v_a_r
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from . import _b_s_l_n
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from . import _c_m_a_p
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13
Lib/fontTools/ttLib/tables/_a_n_k_r.py
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13
Lib/fontTools/ttLib/tables/_a_n_k_r.py
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@ -0,0 +1,13 @@
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from __future__ import print_function, division, absolute_import
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from fontTools.misc.py23 import *
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from .otBase import BaseTTXConverter
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# The anchor point table provides a way to define anchor points.
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# These are points within the coordinate space of a given glyph,
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# independent of the control points used to render the glyph.
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# Anchor points are used in conjunction with the 'kerx' table.
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#
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# https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6ankr.html
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class table__a_n_k_r(BaseTTXConverter):
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pass
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@ -5,7 +5,7 @@ from fontTools.misc.fixedTools import (
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versionToFixed as ve2fi)
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from fontTools.misc.textTools import safeEval
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from fontTools.ttLib import getSearchRange
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from .otBase import ValueRecordFactory, CountReference
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from .otBase import ValueRecordFactory, CountReference, OTTableWriter
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from functools import partial
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import struct
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import logging
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@ -806,6 +806,74 @@ class AATLookup(BaseConverter):
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xmlWriter.newline()
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# The AAT 'ankr' table has an unusual structure: An offset to an AATLookup
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# followed by an offset to a glyph data table. Other than usual, the
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# offsets in the AATLookup are not relative to the beginning of
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# the beginning of the 'ankr' table, but relative to the glyph data table.
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# So, to find the anchor data for a glyph, one needs to add the offset
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# to the data table to the offset found in the AATLookup, and then use
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# the sum of these two offsets to find the actual data.
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class AATLookupWithDataOffset(BaseConverter):
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def read(self, reader, font, tableDict):
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lookupOffset = reader.readULong()
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dataOffset = reader.readULong()
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lookupReader = reader.getSubReader(lookupOffset)
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lookup = AATLookup('DataOffsets', None, None, UShort)
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offsets = lookup.read(lookupReader, font, tableDict)
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result = {}
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for glyph, offset in offsets.items():
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dataReader = reader.getSubReader(offset + dataOffset)
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item = self.tableClass()
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item.decompile(dataReader, font)
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result[glyph] = item
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return result
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def write(self, writer, font, tableDict, value, repeatIndex=None):
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# We do not work with OTTableWriter sub-writers because
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# the offsets in our AATLookup are relative to our data
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# table, for which we need to provide an offset value itself.
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# It might have been possible to somehow make a kludge for
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# performing this indirect offset computation directly inside
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# OTTableWriter. But this would have made the internal logic
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# of OTTableWriter even more complex than it already is,
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# so we decided to roll our own offset computation for the
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# contents of the AATLookup and associated data table.
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offsetByGlyph, offsetByData, dataLen = {}, {}, 0
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compiledData = []
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for glyph in sorted(value, key=font.getGlyphID):
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subWriter = OTTableWriter()
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value[glyph].compile(subWriter, font)
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data = subWriter.getAllData()
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offset = offsetByData.get(data, None)
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if offset == None:
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offset = dataLen
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dataLen = dataLen + len(data)
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offsetByData[data] = offset
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compiledData.append(data)
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offsetByGlyph[glyph] = offset
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# For calculating the offsets to our AATLookup and data table,
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# we can use the regular OTTableWriter infrastructure.
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lookupWriter = writer.getSubWriter()
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lookupWriter.longOffset = True
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lookup = AATLookup('DataOffsets', None, None, UShort)
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lookup.write(lookupWriter, font, tableDict, offsetByGlyph, None)
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dataWriter = writer.getSubWriter()
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dataWriter.longOffset = True
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writer.writeSubTable(lookupWriter)
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writer.writeSubTable(dataWriter)
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for d in compiledData:
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dataWriter.writeData(d)
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def xmlRead(self, attrs, content, font):
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lookup = AATLookup('DataOffsets', None, None, self.tableClass)
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return lookup.xmlRead(attrs, content, font)
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def xmlWrite(self, xmlWriter, font, value, name, attrs):
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lookup = AATLookup('DataOffsets', None, None, self.tableClass)
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lookup.xmlWrite(xmlWriter, font, value, name, attrs)
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class DeltaValue(BaseConverter):
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def read(self, reader, font, tableDict):
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@ -970,13 +1038,16 @@ converterMapping = {
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"DeltaValue": DeltaValue,
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"VarIdxMapValue": VarIdxMapValue,
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"VarDataValue": VarDataValue,
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# AAT
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"MortChain": StructWithLength,
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"MortSubtable": StructWithLength,
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"MorxChain": StructWithLength,
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"MorxSubtable": StructWithLength,
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# "Template" types
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"AATLookup": lambda C: partial(AATLookup, tableClass=C),
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"AATLookupWithDataOffset": lambda C: partial(AATLookupWithDataOffset, tableClass=C),
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"OffsetTo": lambda C: partial(Table, tableClass=C),
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"LOffsetTo": lambda C: partial(LTable, tableClass=C),
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}
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@ -1186,6 +1186,31 @@ otData = [
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('uint16', 'value', None, None, 'A 16-bit offset from the start of the table to the data.'),
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]),
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#
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# ankr
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#
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('ankr', [
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('struct', 'AnchorPoints', None, None, 'Anchor points table.'),
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]),
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('AnchorPointsFormat0', [
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('uint16', 'Format', None, None, 'Format of the anchor points table, = 0.'),
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('uint16', 'Flags', None, None, 'Flags. Currenty unused, set to zero.'),
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('AATLookupWithDataOffset(AnchorGlyphData)', 'Anchors', None, None, 'Table of with anchor overrides for each glyph.'),
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]),
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('AnchorGlyphData', [
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('uint32', 'AnchorPointCount', None, None, 'Number of anchor points for this glyph.'),
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('struct', 'AnchorPoint', 'AnchorPointCount', 0, 'Individual anchor points.'),
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]),
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('AnchorPoint', [
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('int16', 'XCoordinate', None, None, 'X coordinate of this anchor point.'),
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('int16', 'YCoordinate', None, None, 'Y coordinate of this anchor point.'),
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]),
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#
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# bsln
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#
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@ -100,10 +100,10 @@ The following tables are currently supported:
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BASE, CBDT, CBLC, CFF, CFF2, COLR, CPAL, DSIG, EBDT, EBLC, FFTM,
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GDEF, GMAP, GPKG, GPOS, GSUB, HVAR, JSTF, LTSH, MATH, META, MVAR,
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OS/2, SING, STAT, SVG, TSI0, TSI1, TSI2, TSI3, TSI5, TSIB, TSID,
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TSIJ, TSIP, TSIS, TSIV, TTFA, VDMX, VORG, VVAR, avar, bsln, cmap,
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cvar, cvt, feat, fpgm, fvar, gasp, glyf, gvar, hdmx, head, hhea,
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hmtx, kern, lcar, loca, ltag, maxp, meta, mort, morx, name, opbd,
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post, prep, prop, sbix, trak, vhea and vmtx
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TSIJ, TSIP, TSIS, TSIV, TTFA, VDMX, VORG, VVAR, ankr, avar, bsln,
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cmap, cvar, cvt, feat, fpgm, fvar, gasp, glyf, gvar, hdmx, head,
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hhea, hmtx, kern, lcar, loca, ltag, maxp, meta, mort, morx, name,
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opbd, post, prep, prop, sbix, trak, vhea and vmtx
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.. end table list
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Other tables are dumped as hexadecimal data.
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142
Tests/ttLib/tables/_a_n_k_r_test.py
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142
Tests/ttLib/tables/_a_n_k_r_test.py
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@ -0,0 +1,142 @@
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# coding: utf-8
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from __future__ import print_function, division, absolute_import, unicode_literals
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from fontTools.misc.py23 import *
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from fontTools.misc.testTools import FakeFont, getXML, parseXML
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from fontTools.misc.textTools import deHexStr, hexStr
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from fontTools.ttLib import newTable
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import unittest
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# This is the anchor points table of the first font file in
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# “/Library/Fonts/Devanagari Sangam MN.ttc” on macOS 10.12.6.
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# For testing, we’ve changed the GlyphIDs to smaller values.
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# Also, in the AATLookup, we’ve changed GlyphDataOffset value
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# for the end-of-table marker from 0xFFFF to 0 since that is
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# what our encoder emits. (The value for end-of-table markers
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# does not actually matter).
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ANKR_FORMAT_0_DATA = deHexStr(
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'0000 0000 ' # 0: Format=0, Flags=0
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'0000 000C ' # 4: LookupTableOffset=12
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'0000 0024 ' # 8: GlyphDataTableOffset=36
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'0006 0004 0002 ' # 12: LookupFormat=6, UnitSize=4, NUnits=2
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'0008 0001 0000 ' # 18: SearchRange=8, EntrySelector=1, RangeShift=0
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'0001 0000 ' # 24: Glyph=A, GlyphDataOffset=0 (+GlyphDataOffset=36)
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'0003 0008 ' # 28: Glyph=C, GlyphDataOffset=8 (+GlyphDataOffset=44)
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'FFFF 0000 ' # 32: Glyph=<end>, GlyphDataOffset=<n/a>
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'0000 0001 ' # 36: GlyphData[A].NumPoints=1
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'0235 045E ' # 40: GlyphData[A].Points[0].X=565, .Y=1118
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'0000 0001 ' # 44: GlyphData[C].NumPoints=1
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'FED2 045E ' # 48: GlyphData[C].Points[0].X=-302, .Y=1118
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) # 52: <end>
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assert len(ANKR_FORMAT_0_DATA) == 52
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ANKR_FORMAT_0_XML = [
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'<AnchorPoints Format="0">',
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' <Flags value="0"/>',
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' <Anchors>',
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' <Lookup glyph="A">',
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' <!-- AnchorPointCount=1 -->',
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' <AnchorPoint index="0">',
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' <XCoordinate value="565"/>',
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' <YCoordinate value="1118"/>',
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' </AnchorPoint>',
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' </Lookup>',
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' <Lookup glyph="C">',
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' <!-- AnchorPointCount=1 -->',
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' <AnchorPoint index="0">',
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' <XCoordinate value="-302"/>',
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' <YCoordinate value="1118"/>',
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' </AnchorPoint>',
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' </Lookup>',
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' </Anchors>',
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'</AnchorPoints>',
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]
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# Constructed test case where glyphs A and D share the same anchor data.
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ANKR_FORMAT_0_SHARING_DATA = deHexStr(
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'0000 0000 ' # 0: Format=0, Flags=0
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'0000 000C ' # 4: LookupTableOffset=12
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'0000 0028 ' # 8: GlyphDataTableOffset=40
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'0006 0004 0003 ' # 12: LookupFormat=6, UnitSize=4, NUnits=3
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'0008 0001 0004 ' # 18: SearchRange=8, EntrySelector=1, RangeShift=4
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'0001 0000 ' # 24: Glyph=A, GlyphDataOffset=0 (+GlyphDataOffset=36)
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'0003 0008 ' # 28: Glyph=C, GlyphDataOffset=8 (+GlyphDataOffset=44)
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'0004 0000 ' # 32: Glyph=D, GlyphDataOffset=0 (+GlyphDataOffset=36)
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'FFFF 0000 ' # 36: Glyph=<end>, GlyphDataOffset=<n/a>
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'0000 0001 ' # 40: GlyphData[A].NumPoints=1
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'0235 045E ' # 44: GlyphData[A].Points[0].X=565, .Y=1118
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'0000 0002 ' # 48: GlyphData[C].NumPoints=2
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'000B 000C ' # 52: GlyphData[C].Points[0].X=11, .Y=12
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'001B 001C ' # 56: GlyphData[C].Points[1].X=27, .Y=28
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) # 60: <end>
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assert len(ANKR_FORMAT_0_SHARING_DATA) == 60
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ANKR_FORMAT_0_SHARING_XML = [
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'<AnchorPoints Format="0">',
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' <Flags value="0"/>',
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' <Anchors>',
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' <Lookup glyph="A">',
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' <!-- AnchorPointCount=1 -->',
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' <AnchorPoint index="0">',
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' <XCoordinate value="565"/>',
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' <YCoordinate value="1118"/>',
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' </AnchorPoint>',
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' </Lookup>',
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' <Lookup glyph="C">',
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' <!-- AnchorPointCount=2 -->',
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' <AnchorPoint index="0">',
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' <XCoordinate value="11"/>',
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' <YCoordinate value="12"/>',
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' </AnchorPoint>',
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' <AnchorPoint index="1">',
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' <XCoordinate value="27"/>',
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' <YCoordinate value="28"/>',
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' </AnchorPoint>',
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' </Lookup>',
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' <Lookup glyph="D">',
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' <!-- AnchorPointCount=1 -->',
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' <AnchorPoint index="0">',
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' <XCoordinate value="565"/>',
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' <YCoordinate value="1118"/>',
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' </AnchorPoint>',
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' </Lookup>',
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' </Anchors>',
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'</AnchorPoints>',
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]
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class ANKRTest(unittest.TestCase):
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@classmethod
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def setUpClass(cls):
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cls.maxDiff = None
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cls.font = FakeFont(['.notdef', 'A', 'B', 'C', 'D'])
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def decompileToXML(self, data, xml):
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table = newTable('ankr')
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table.decompile(data, self.font)
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self.assertEqual(getXML(table.toXML), xml)
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def compileFromXML(self, xml, data):
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table = newTable('ankr')
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for name, attrs, content in parseXML(xml):
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table.fromXML(name, attrs, content, font=self.font)
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self.assertEqual(hexStr(table.compile(self.font)), hexStr(data))
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def roundtrip(self, data, xml):
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self.decompileToXML(data, xml)
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self.compileFromXML(xml, data)
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def testFormat0(self):
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self.roundtrip(ANKR_FORMAT_0_DATA, ANKR_FORMAT_0_XML)
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def testFormat0_sharing(self):
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self.roundtrip(ANKR_FORMAT_0_SHARING_DATA, ANKR_FORMAT_0_SHARING_XML)
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if __name__ == '__main__':
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import sys
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sys.exit(unittest.main())
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