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Diffstat (limited to 'gfx/ots/src/math.cc')
| -rw-r--r-- | gfx/ots/src/math.cc | 619 |
1 files changed, 619 insertions, 0 deletions
diff --git a/gfx/ots/src/math.cc b/gfx/ots/src/math.cc new file mode 100644 index 000000000..36417dc29 --- /dev/null +++ b/gfx/ots/src/math.cc @@ -0,0 +1,619 @@ +// Copyright (c) 2014 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +// We use an underscore to avoid confusion with the standard math.h library. +#include "math_.h" + +#include <limits> +#include <vector> + +#include "layout.h" +#include "maxp.h" + +// MATH - The MATH Table +// The specification is not yet public but has been submitted to the MPEG group +// in response to the 'Call for Proposals for ISO/IEC 14496-22 "Open Font +// Format" Color Font Technology and MATH layout support'. Meanwhile, you can +// contact Microsoft's engineer Murray Sargent to obtain a copy. + +#define TABLE_NAME "MATH" + +namespace { + +// The size of MATH header. +// Version +// MathConstants +// MathGlyphInfo +// MathVariants +const unsigned kMathHeaderSize = 4 + 3 * 2; + +// The size of the MathGlyphInfo header. +// MathItalicsCorrectionInfo +// MathTopAccentAttachment +// ExtendedShapeCoverage +// MathKernInfo +const unsigned kMathGlyphInfoHeaderSize = 4 * 2; + +// The size of the MathValueRecord. +// Value +// DeviceTable +const unsigned kMathValueRecordSize = 2 * 2; + +// The size of the GlyphPartRecord. +// glyph +// StartConnectorLength +// EndConnectorLength +// FullAdvance +// PartFlags +const unsigned kGlyphPartRecordSize = 5 * 2; + +// Shared Table: MathValueRecord + +bool ParseMathValueRecord(const ots::Font *font, + ots::Buffer* subtable, const uint8_t *data, + const size_t length) { + // Check the Value field. + if (!subtable->Skip(2)) { + return OTS_FAILURE(); + } + + // Check the offset to device table. + uint16_t offset = 0; + if (!subtable->ReadU16(&offset)) { + return OTS_FAILURE(); + } + if (offset) { + if (offset >= length) { + return OTS_FAILURE(); + } + if (!ots::ParseDeviceTable(font, data + offset, length - offset)) { + return OTS_FAILURE(); + } + } + + return true; +} + +bool ParseMathConstantsTable(const ots::Font *font, + const uint8_t *data, size_t length) { + ots::Buffer subtable(data, length); + + // Part 1: int16 or uint16 constants. + // ScriptPercentScaleDown + // ScriptScriptPercentScaleDown + // DelimitedSubFormulaMinHeight + // DisplayOperatorMinHeight + if (!subtable.Skip(4 * 2)) { + return OTS_FAILURE(); + } + + // Part 2: MathValueRecord constants. + // MathLeading + // AxisHeight + // AccentBaseHeight + // FlattenedAccentBaseHeight + // SubscriptShiftDown + // SubscriptTopMax + // SubscriptBaselineDropMin + // SuperscriptShiftUp + // SuperscriptShiftUpCramped + // SuperscriptBottomMin + // + // SuperscriptBaselineDropMax + // SubSuperscriptGapMin + // SuperscriptBottomMaxWithSubscript + // SpaceAfterScript + // UpperLimitGapMin + // UpperLimitBaselineRiseMin + // LowerLimitGapMin + // LowerLimitBaselineDropMin + // StackTopShiftUp + // StackTopDisplayStyleShiftUp + // + // StackBottomShiftDown + // StackBottomDisplayStyleShiftDown + // StackGapMin + // StackDisplayStyleGapMin + // StretchStackTopShiftUp + // StretchStackBottomShiftDown + // StretchStackGapAboveMin + // StretchStackGapBelowMin + // FractionNumeratorShiftUp + // FractionNumeratorDisplayStyleShiftUp + // + // FractionDenominatorShiftDown + // FractionDenominatorDisplayStyleShiftDown + // FractionNumeratorGapMin + // FractionNumDisplayStyleGapMin + // FractionRuleThickness + // FractionDenominatorGapMin + // FractionDenomDisplayStyleGapMin + // SkewedFractionHorizontalGap + // SkewedFractionVerticalGap + // OverbarVerticalGap + // + // OverbarRuleThickness + // OverbarExtraAscender + // UnderbarVerticalGap + // UnderbarRuleThickness + // UnderbarExtraDescender + // RadicalVerticalGap + // RadicalDisplayStyleVerticalGap + // RadicalRuleThickness + // RadicalExtraAscender + // RadicalKernBeforeDegree + // + // RadicalKernAfterDegree + for (unsigned i = 0; i < static_cast<unsigned>(51); ++i) { + if (!ParseMathValueRecord(font, &subtable, data, length)) { + return OTS_FAILURE(); + } + } + + // Part 3: uint16 constant + // RadicalDegreeBottomRaisePercent + if (!subtable.Skip(2)) { + return OTS_FAILURE(); + } + + return true; +} + +bool ParseMathValueRecordSequenceForGlyphs(const ots::Font *font, + ots::Buffer* subtable, + const uint8_t *data, + const size_t length, + const uint16_t num_glyphs) { + // Check the header. + uint16_t offset_coverage = 0; + uint16_t sequence_count = 0; + if (!subtable->ReadU16(&offset_coverage) || + !subtable->ReadU16(&sequence_count)) { + return OTS_FAILURE(); + } + + const unsigned sequence_end = static_cast<unsigned>(2 * 2) + + sequence_count * kMathValueRecordSize; + if (sequence_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE(); + } + + // Check coverage table. + if (offset_coverage < sequence_end || offset_coverage >= length) { + return OTS_FAILURE(); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, + length - offset_coverage, + num_glyphs, sequence_count)) { + return OTS_FAILURE(); + } + + // Check sequence. + for (unsigned i = 0; i < sequence_count; ++i) { + if (!ParseMathValueRecord(font, subtable, data, length)) { + return OTS_FAILURE(); + } + } + + return true; +} + +bool ParseMathItalicsCorrectionInfoTable(const ots::Font *font, + const uint8_t *data, + size_t length, + const uint16_t num_glyphs) { + ots::Buffer subtable(data, length); + return ParseMathValueRecordSequenceForGlyphs(font, &subtable, data, length, + num_glyphs); +} + +bool ParseMathTopAccentAttachmentTable(const ots::Font *font, + const uint8_t *data, + size_t length, + const uint16_t num_glyphs) { + ots::Buffer subtable(data, length); + return ParseMathValueRecordSequenceForGlyphs(font, &subtable, data, length, + num_glyphs); +} + +bool ParseMathKernTable(const ots::Font *font, + const uint8_t *data, size_t length) { + ots::Buffer subtable(data, length); + + // Check the Height count. + uint16_t height_count = 0; + if (!subtable.ReadU16(&height_count)) { + return OTS_FAILURE(); + } + + // Check the Correction Heights. + for (unsigned i = 0; i < height_count; ++i) { + if (!ParseMathValueRecord(font, &subtable, data, length)) { + return OTS_FAILURE(); + } + } + + // Check the Kern Values. + for (unsigned i = 0; i <= height_count; ++i) { + if (!ParseMathValueRecord(font, &subtable, data, length)) { + return OTS_FAILURE(); + } + } + + return true; +} + +bool ParseMathKernInfoTable(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs) { + ots::Buffer subtable(data, length); + + // Check the header. + uint16_t offset_coverage = 0; + uint16_t sequence_count = 0; + if (!subtable.ReadU16(&offset_coverage) || + !subtable.ReadU16(&sequence_count)) { + return OTS_FAILURE(); + } + + const unsigned sequence_end = static_cast<unsigned>(2 * 2) + + sequence_count * 4 * 2; + if (sequence_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE(); + } + + // Check coverage table. + if (offset_coverage < sequence_end || offset_coverage >= length) { + return OTS_FAILURE(); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, length - offset_coverage, + num_glyphs, sequence_count)) { + return OTS_FAILURE(); + } + + // Check sequence of MathKernInfoRecord + for (unsigned i = 0; i < sequence_count; ++i) { + // Check TopRight, TopLeft, BottomRight and BottomLeft Math Kern. + for (unsigned j = 0; j < 4; ++j) { + uint16_t offset_math_kern = 0; + if (!subtable.ReadU16(&offset_math_kern)) { + return OTS_FAILURE(); + } + if (offset_math_kern) { + if (offset_math_kern < sequence_end || offset_math_kern >= length || + !ParseMathKernTable(font, data + offset_math_kern, + length - offset_math_kern)) { + return OTS_FAILURE(); + } + } + } + } + + return true; +} + +bool ParseMathGlyphInfoTable(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs) { + ots::Buffer subtable(data, length); + + // Check Header. + uint16_t offset_math_italics_correction_info = 0; + uint16_t offset_math_top_accent_attachment = 0; + uint16_t offset_extended_shaped_coverage = 0; + uint16_t offset_math_kern_info = 0; + if (!subtable.ReadU16(&offset_math_italics_correction_info) || + !subtable.ReadU16(&offset_math_top_accent_attachment) || + !subtable.ReadU16(&offset_extended_shaped_coverage) || + !subtable.ReadU16(&offset_math_kern_info)) { + return OTS_FAILURE(); + } + + // Check subtables. + // The specification does not say whether the offsets for + // MathItalicsCorrectionInfo, MathTopAccentAttachment and MathKernInfo may + // be NULL, but that's the case in some fonts (e.g STIX) so we accept that. + if (offset_math_italics_correction_info) { + if (offset_math_italics_correction_info >= length || + offset_math_italics_correction_info < kMathGlyphInfoHeaderSize || + !ParseMathItalicsCorrectionInfoTable( + font, data + offset_math_italics_correction_info, + length - offset_math_italics_correction_info, + num_glyphs)) { + return OTS_FAILURE(); + } + } + if (offset_math_top_accent_attachment) { + if (offset_math_top_accent_attachment >= length || + offset_math_top_accent_attachment < kMathGlyphInfoHeaderSize || + !ParseMathTopAccentAttachmentTable(font, data + + offset_math_top_accent_attachment, + length - + offset_math_top_accent_attachment, + num_glyphs)) { + return OTS_FAILURE(); + } + } + if (offset_extended_shaped_coverage) { + if (offset_extended_shaped_coverage >= length || + offset_extended_shaped_coverage < kMathGlyphInfoHeaderSize || + !ots::ParseCoverageTable(font, data + offset_extended_shaped_coverage, + length - offset_extended_shaped_coverage, + num_glyphs)) { + return OTS_FAILURE(); + } + } + if (offset_math_kern_info) { + if (offset_math_kern_info >= length || + offset_math_kern_info < kMathGlyphInfoHeaderSize || + !ParseMathKernInfoTable(font, data + offset_math_kern_info, + length - offset_math_kern_info, num_glyphs)) { + return OTS_FAILURE(); + } + } + + return true; +} + +bool ParseGlyphAssemblyTable(const ots::Font *font, + const uint8_t *data, + size_t length, const uint16_t num_glyphs) { + ots::Buffer subtable(data, length); + + // Check the header. + uint16_t part_count = 0; + if (!ParseMathValueRecord(font, &subtable, data, length) || + !subtable.ReadU16(&part_count)) { + return OTS_FAILURE(); + } + + const unsigned sequence_end = kMathValueRecordSize + + static_cast<unsigned>(2) + part_count * kGlyphPartRecordSize; + if (sequence_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE(); + } + + // Check the sequence of GlyphPartRecord. + for (unsigned i = 0; i < part_count; ++i) { + uint16_t glyph = 0; + uint16_t part_flags = 0; + if (!subtable.ReadU16(&glyph) || + !subtable.Skip(2 * 3) || + !subtable.ReadU16(&part_flags)) { + return OTS_FAILURE(); + } + if (glyph >= num_glyphs) { + return OTS_FAILURE_MSG("bad glyph ID: %u", glyph); + } + if (part_flags & ~0x00000001) { + return OTS_FAILURE_MSG("unknown part flag: %u", part_flags); + } + } + + return true; +} + +bool ParseMathGlyphConstructionTable(const ots::Font *font, + const uint8_t *data, + size_t length, const uint16_t num_glyphs) { + ots::Buffer subtable(data, length); + + // Check the header. + uint16_t offset_glyph_assembly = 0; + uint16_t variant_count = 0; + if (!subtable.ReadU16(&offset_glyph_assembly) || + !subtable.ReadU16(&variant_count)) { + return OTS_FAILURE(); + } + + const unsigned sequence_end = static_cast<unsigned>(2 * 2) + + variant_count * 2 * 2; + if (sequence_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE(); + } + + // Check the GlyphAssembly offset. + if (offset_glyph_assembly) { + if (offset_glyph_assembly >= length || + offset_glyph_assembly < sequence_end) { + return OTS_FAILURE(); + } + if (!ParseGlyphAssemblyTable(font, data + offset_glyph_assembly, + length - offset_glyph_assembly, num_glyphs)) { + return OTS_FAILURE(); + } + } + + // Check the sequence of MathGlyphVariantRecord. + for (unsigned i = 0; i < variant_count; ++i) { + uint16_t glyph = 0; + if (!subtable.ReadU16(&glyph) || + !subtable.Skip(2)) { + return OTS_FAILURE(); + } + if (glyph >= num_glyphs) { + return OTS_FAILURE_MSG("bad glyph ID: %u", glyph); + } + } + + return true; +} + +bool ParseMathGlyphConstructionSequence(const ots::Font *font, + ots::Buffer* subtable, + const uint8_t *data, + size_t length, + const uint16_t num_glyphs, + uint16_t offset_coverage, + uint16_t glyph_count, + const unsigned sequence_end) { + // Zero glyph count, nothing to parse. + if (!glyph_count) { + return true; + } + + // Check coverage table. + if (offset_coverage < sequence_end || offset_coverage >= length) { + return OTS_FAILURE(); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, + length - offset_coverage, + num_glyphs, glyph_count)) { + return OTS_FAILURE(); + } + + // Check sequence of MathGlyphConstruction. + for (unsigned i = 0; i < glyph_count; ++i) { + uint16_t offset_glyph_construction = 0; + if (!subtable->ReadU16(&offset_glyph_construction)) { + return OTS_FAILURE(); + } + if (offset_glyph_construction < sequence_end || + offset_glyph_construction >= length || + !ParseMathGlyphConstructionTable(font, data + offset_glyph_construction, + length - offset_glyph_construction, + num_glyphs)) { + return OTS_FAILURE(); + } + } + + return true; +} + +bool ParseMathVariantsTable(const ots::Font *font, + const uint8_t *data, + size_t length, const uint16_t num_glyphs) { + ots::Buffer subtable(data, length); + + // Check the header. + uint16_t offset_vert_glyph_coverage = 0; + uint16_t offset_horiz_glyph_coverage = 0; + uint16_t vert_glyph_count = 0; + uint16_t horiz_glyph_count = 0; + if (!subtable.Skip(2) || // MinConnectorOverlap + !subtable.ReadU16(&offset_vert_glyph_coverage) || + !subtable.ReadU16(&offset_horiz_glyph_coverage) || + !subtable.ReadU16(&vert_glyph_count) || + !subtable.ReadU16(&horiz_glyph_count)) { + return OTS_FAILURE(); + } + + const unsigned sequence_end = 5 * 2 + vert_glyph_count * 2 + + horiz_glyph_count * 2; + if (sequence_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE(); + } + + if (!ParseMathGlyphConstructionSequence(font, &subtable, data, length, num_glyphs, + offset_vert_glyph_coverage, + vert_glyph_count, + sequence_end) || + !ParseMathGlyphConstructionSequence(font, &subtable, data, length, num_glyphs, + offset_horiz_glyph_coverage, + horiz_glyph_count, + sequence_end)) { + return OTS_FAILURE(); + } + + return true; +} + +} // namespace + +#define DROP_THIS_TABLE(msg_) \ + do { \ + OTS_FAILURE_MSG(msg_ ", table discarded"); \ + font->math->data = 0; \ + font->math->length = 0; \ + } while (0) + +namespace ots { + +bool ots_math_parse(Font *font, const uint8_t *data, size_t length) { + // Grab the number of glyphs in the font from the maxp table to check + // GlyphIDs in MATH table. + if (!font->maxp) { + return OTS_FAILURE(); + } + const uint16_t num_glyphs = font->maxp->num_glyphs; + + Buffer table(data, length); + + OpenTypeMATH* math = new OpenTypeMATH; + font->math = math; + + uint32_t version = 0; + if (!table.ReadU32(&version)) { + return OTS_FAILURE(); + } + if (version != 0x00010000) { + DROP_THIS_TABLE("bad MATH version"); + return true; + } + + uint16_t offset_math_constants = 0; + uint16_t offset_math_glyph_info = 0; + uint16_t offset_math_variants = 0; + if (!table.ReadU16(&offset_math_constants) || + !table.ReadU16(&offset_math_glyph_info) || + !table.ReadU16(&offset_math_variants)) { + return OTS_FAILURE(); + } + + if (offset_math_constants >= length || + offset_math_constants < kMathHeaderSize || + offset_math_glyph_info >= length || + offset_math_glyph_info < kMathHeaderSize || + offset_math_variants >= length || + offset_math_variants < kMathHeaderSize) { + DROP_THIS_TABLE("bad offset in MATH header"); + return true; + } + + if (!ParseMathConstantsTable(font, data + offset_math_constants, + length - offset_math_constants)) { + DROP_THIS_TABLE("failed to parse MathConstants table"); + return true; + } + if (!ParseMathGlyphInfoTable(font, data + offset_math_glyph_info, + length - offset_math_glyph_info, num_glyphs)) { + DROP_THIS_TABLE("failed to parse MathGlyphInfo table"); + return true; + } + if (!ParseMathVariantsTable(font, data + offset_math_variants, + length - offset_math_variants, num_glyphs)) { + DROP_THIS_TABLE("failed to parse MathVariants table"); + return true; + } + + math->data = data; + math->length = length; + return true; +} + +bool ots_math_should_serialise(Font *font) { + return font->math != NULL && font->math->data != NULL; +} + +bool ots_math_serialise(OTSStream *out, Font *font) { + if (!out->Write(font->math->data, font->math->length)) { + return OTS_FAILURE(); + } + + return true; +} + +void ots_math_reuse(Font *font, Font *other) { + font->math = other->math; + font->math_reused = true; +} + +void ots_math_free(Font *font) { + delete font->math; +} + +} // namespace ots + +#undef TABLE_NAME +#undef DROP_THIS_TABLE |