1 /* This Source Code Form is subject to the terms of the Mozilla Public 2 * License, v. 2.0. If a copy of the MPL was not distributed with this 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 4 5 #ifndef GFX_MATH_TABLE_H 6 #define GFX_MATH_TABLE_H 7 8 #include "gfxFont.h" 9 10 /** 11 * Used by |gfxFont| to represent the MATH table of an OpenType font. 12 * Each |gfxFont| owns at most one |gfxMathTable| instance. 13 */ 14 class gfxMathTable { 15 public: 16 /** 17 * @param aFace The HarfBuzz face containing the math table. 18 * @param aSize The font size to pass to HarfBuzz. 19 */ 20 gfxMathTable(hb_face_t *aFace, gfxFloat aSize); 21 22 /** 23 * Releases our reference to the MATH table and cleans up everything else. 24 */ 25 ~gfxMathTable(); 26 27 enum MathConstant { 28 // The order of the constants must match the order of the fields 29 // defined in the MATH table. 30 ScriptPercentScaleDown, 31 ScriptScriptPercentScaleDown, 32 DelimitedSubFormulaMinHeight, 33 DisplayOperatorMinHeight, 34 MathLeading, 35 AxisHeight, 36 AccentBaseHeight, 37 FlattenedAccentBaseHeight, 38 SubscriptShiftDown, 39 SubscriptTopMax, 40 SubscriptBaselineDropMin, 41 SuperscriptShiftUp, 42 SuperscriptShiftUpCramped, 43 SuperscriptBottomMin, 44 SuperscriptBaselineDropMax, 45 SubSuperscriptGapMin, 46 SuperscriptBottomMaxWithSubscript, 47 SpaceAfterScript, 48 UpperLimitGapMin, 49 UpperLimitBaselineRiseMin, 50 LowerLimitGapMin, 51 LowerLimitBaselineDropMin, 52 StackTopShiftUp, 53 StackTopDisplayStyleShiftUp, 54 StackBottomShiftDown, 55 StackBottomDisplayStyleShiftDown, 56 StackGapMin, 57 StackDisplayStyleGapMin, 58 StretchStackTopShiftUp, 59 StretchStackBottomShiftDown, 60 StretchStackGapAboveMin, 61 StretchStackGapBelowMin, 62 FractionNumeratorShiftUp, 63 FractionNumeratorDisplayStyleShiftUp, 64 FractionDenominatorShiftDown, 65 FractionDenominatorDisplayStyleShiftDown, 66 FractionNumeratorGapMin, 67 FractionNumDisplayStyleGapMin, 68 FractionRuleThickness, 69 FractionDenominatorGapMin, 70 FractionDenomDisplayStyleGapMin, 71 SkewedFractionHorizontalGap, 72 SkewedFractionVerticalGap, 73 OverbarVerticalGap, 74 OverbarRuleThickness, 75 OverbarExtraAscender, 76 UnderbarVerticalGap, 77 UnderbarRuleThickness, 78 UnderbarExtraDescender, 79 RadicalVerticalGap, 80 RadicalDisplayStyleVerticalGap, 81 RadicalRuleThickness, 82 RadicalExtraAscender, 83 RadicalKernBeforeDegree, 84 RadicalKernAfterDegree, 85 RadicalDegreeBottomRaisePercent 86 }; 87 88 /** 89 * Returns the value of the specified constant from the MATH table. 90 */ 91 gfxFloat Constant(MathConstant aConstant) const; 92 93 /** 94 * Returns the value of the specified constant in app units. 95 */ Constant(MathConstant aConstant,uint32_t aAppUnitsPerDevPixel)96 nscoord Constant(MathConstant aConstant, 97 uint32_t aAppUnitsPerDevPixel) const { 98 return NSToCoordRound(Constant(aConstant) * aAppUnitsPerDevPixel); 99 } 100 101 /** 102 * If the MATH table contains an italic correction for that glyph, this 103 * function returns the corresponding value. Otherwise it returns 0. 104 */ 105 gfxFloat ItalicsCorrection(uint32_t aGlyphID) const; 106 107 /** 108 * @param aGlyphID glyph index of the character we want to stretch 109 * @param aVertical direction of the stretching (vertical/horizontal) 110 * @param aSize the desired size variant 111 * 112 * Returns the glyph index of the desired size variant or 0 if there is not 113 * any such size variant. 114 */ 115 uint32_t VariantsSize(uint32_t aGlyphID, bool aVertical, 116 uint16_t aSize) const; 117 118 /** 119 * @param aGlyphID glyph index of the character we want to stretch 120 * @param aVertical direction of the stretching (vertical/horizontal) 121 * @param aGlyphs pre-allocated buffer of 4 elements where the glyph 122 * indexes (or 0 for absent parts) will be stored. The parts are stored in 123 * the order expected by the nsMathMLChar: Top (or Left), Middle, Bottom 124 * (or Right), Glue. 125 * 126 * Tries to fill-in aGlyphs with the relevant glyph indexes and returns 127 * whether the operation was successful. The function returns false if 128 * there is not any assembly for the character we want to stretch or if 129 * the format is not supported by the nsMathMLChar code. 130 * 131 */ 132 bool VariantsParts(uint32_t aGlyphID, bool aVertical, 133 uint32_t aGlyphs[4]) const; 134 135 private: 136 // size-specific font object, owned by the gfxMathTable 137 hb_font_t *mHBFont; 138 139 static const unsigned int kMaxCachedSizeCount = 10; 140 struct MathVariantCacheEntry { 141 uint32_t glyphID; 142 bool vertical; 143 uint32_t sizes[kMaxCachedSizeCount]; 144 uint32_t parts[4]; 145 bool arePartsValid; 146 }; 147 mutable MathVariantCacheEntry mMathVariantCache; 148 void ClearCache() const; 149 void UpdateMathVariantCache(uint32_t aGlyphID, bool aVertical) const; 150 }; 151 152 #endif 153