1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/thebes/gfxMathTable.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,122 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +#ifndef GFX_MATH_TABLE_H
1.9 +#define GFX_MATH_TABLE_H
1.10 +
1.11 +#include "gfxFont.h"
1.12 +
1.13 +struct Coverage;
1.14 +struct GlyphAssembly;
1.15 +struct MATHTableHeader;
1.16 +struct MathConstants;
1.17 +struct MathGlyphConstruction;
1.18 +struct MathGlyphInfo;
1.19 +struct MathVariants;
1.20 +
1.21 +/**
1.22 + * Used by |gfxFontEntry| to represent the MATH table of an OpenType font.
1.23 + * Each |gfxFontEntry| owns at most one |gfxMathTable| instance.
1.24 + */
1.25 +class gfxMathTable
1.26 +{
1.27 +public:
1.28 + /**
1.29 + * @param aMathTable The MATH table from the OpenType font
1.30 + *
1.31 + * The gfxMathTable object takes over ownership of the blob references
1.32 + * that are passed in, and will hb_blob_destroy() them when finished;
1.33 + * the caller should -not- destroy this reference.
1.34 + */
1.35 + gfxMathTable(hb_blob_t* aMathTable);
1.36 +
1.37 + /**
1.38 + * Releases our reference to the MATH table and cleans up everything else.
1.39 + */
1.40 + ~gfxMathTable();
1.41 +
1.42 + /**
1.43 + * Returns the value of the specified constant from the MATH table.
1.44 + */
1.45 + int32_t GetMathConstant(gfxFontEntry::MathConstant aConstant);
1.46 +
1.47 + /**
1.48 + * If the MATH table contains an italic correction for that glyph, this
1.49 + * function gets the value and returns true. Otherwise it returns false.
1.50 + */
1.51 + bool
1.52 + GetMathItalicsCorrection(uint32_t aGlyphID, int16_t* aItalicCorrection);
1.53 +
1.54 + /**
1.55 + * @param aGlyphID glyph index of the character we want to stretch
1.56 + * @param aVertical direction of the stretching (vertical/horizontal)
1.57 + * @param aSize the desired size variant
1.58 + *
1.59 + * Returns the glyph index of the desired size variant or 0 if there is not
1.60 + * any such size variant.
1.61 + */
1.62 + uint32_t GetMathVariantsSize(uint32_t aGlyphID, bool aVertical,
1.63 + uint16_t aSize);
1.64 +
1.65 + /**
1.66 + * @param aGlyphID glyph index of the character we want to stretch
1.67 + * @param aVertical direction of the stretching (vertical/horizontal)
1.68 + * @param aGlyphs pre-allocated buffer of 4 elements where the glyph
1.69 + * indexes (or 0 for absent parts) will be stored. The parts are stored in
1.70 + * the order expected by the nsMathMLChar: Top (or Left), Middle, Bottom
1.71 + * (or Right), Glue.
1.72 + *
1.73 + * Tries to fill-in aGlyphs with the relevant glyph indexes and returns
1.74 + * whether the operation was successful. The function returns false if
1.75 + * there is not any assembly for the character we want to stretch or if
1.76 + * the format is not supported by the nsMathMLChar code.
1.77 + *
1.78 + */
1.79 + bool GetMathVariantsParts(uint32_t aGlyphID, bool aVertical,
1.80 + uint32_t aGlyphs[4]);
1.81 +
1.82 +protected:
1.83 + friend class gfxFontEntry;
1.84 + // This allows gfxFontEntry to verify the validity of the main headers
1.85 + // before starting to use the MATH table.
1.86 + bool HasValidHeaders();
1.87 +
1.88 +private:
1.89 + // HarfBuzz blob where the MATH table is stored.
1.90 + hb_blob_t* mMathTable;
1.91 +
1.92 + // Cached values for the latest (mGlyphID, mVertical) pair that has been
1.93 + // accessed and the corresponding glyph construction. These are verified
1.94 + // by SelectGlyphConstruction and updated if necessary.
1.95 + // mGlyphConstruction will be set to nullptr if no construction is defined
1.96 + // for the glyph. If non-null, its mGlyphAssembly and mVariantCount fields
1.97 + // may be safely read, but no further validation will have been done.
1.98 + const MathGlyphConstruction* mGlyphConstruction;
1.99 + uint32_t mGlyphID;
1.100 + bool mVertical;
1.101 + void SelectGlyphConstruction(uint32_t aGlyphID, bool aVertical);
1.102 +
1.103 + // Access to some structures of the MATH table.
1.104 + // These accessors just return a pointer, but do NOT themselves check the
1.105 + // validity of anything. Until we've checked that HasValidHeaders (which
1.106 + // does validate them) returns true, they might return pointers that cannot
1.107 + // even safely be dereferenced. GetGlyphAssembly may return nullptr if the
1.108 + // given glyph has no assembly defined.
1.109 + const MATHTableHeader* GetMATHTableHeader();
1.110 + const MathConstants* GetMathConstants();
1.111 + const MathGlyphInfo* GetMathGlyphInfo();
1.112 + const MathVariants* GetMathVariants();
1.113 + const GlyphAssembly* GetGlyphAssembly(uint32_t aGlyphID, bool aVertical);
1.114 +
1.115 + // Verify whether a structure or an offset belongs to the math data and can
1.116 + // be read safely.
1.117 + bool ValidStructure(const char* aStructStart, uint16_t aStructSize);
1.118 + bool ValidOffset(const char* aOffsetStart, uint16_t aOffset);
1.119 +
1.120 + // Get the coverage index of a glyph index from an Open Type coverage table
1.121 + // or -1 if the glyph index is not found.
1.122 + int32_t GetCoverageIndex(const Coverage* aCoverage, uint32_t aGlyph);
1.123 +};
1.124 +
1.125 +#endif
