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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 : {
16 : public:
17 : /**
18 : * @param aFace The HarfBuzz face containing the math table.
19 : * @param aSize The font size to pass to HarfBuzz.
20 : */
21 : gfxMathTable(hb_face_t *aFace, gfxFloat aSize);
22 :
23 : /**
24 : * Releases our reference to the MATH table and cleans up everything else.
25 : */
26 : ~gfxMathTable();
27 :
28 : enum MathConstant {
29 : // The order of the constants must match the order of the fields
30 : // defined in the MATH table.
31 : ScriptPercentScaleDown,
32 : ScriptScriptPercentScaleDown,
33 : DelimitedSubFormulaMinHeight,
34 : DisplayOperatorMinHeight,
35 : MathLeading,
36 : AxisHeight,
37 : AccentBaseHeight,
38 : FlattenedAccentBaseHeight,
39 : SubscriptShiftDown,
40 : SubscriptTopMax,
41 : SubscriptBaselineDropMin,
42 : SuperscriptShiftUp,
43 : SuperscriptShiftUpCramped,
44 : SuperscriptBottomMin,
45 : SuperscriptBaselineDropMax,
46 : SubSuperscriptGapMin,
47 : SuperscriptBottomMaxWithSubscript,
48 : SpaceAfterScript,
49 : UpperLimitGapMin,
50 : UpperLimitBaselineRiseMin,
51 : LowerLimitGapMin,
52 : LowerLimitBaselineDropMin,
53 : StackTopShiftUp,
54 : StackTopDisplayStyleShiftUp,
55 : StackBottomShiftDown,
56 : StackBottomDisplayStyleShiftDown,
57 : StackGapMin,
58 : StackDisplayStyleGapMin,
59 : StretchStackTopShiftUp,
60 : StretchStackBottomShiftDown,
61 : StretchStackGapAboveMin,
62 : StretchStackGapBelowMin,
63 : FractionNumeratorShiftUp,
64 : FractionNumeratorDisplayStyleShiftUp,
65 : FractionDenominatorShiftDown,
66 : FractionDenominatorDisplayStyleShiftDown,
67 : FractionNumeratorGapMin,
68 : FractionNumDisplayStyleGapMin,
69 : FractionRuleThickness,
70 : FractionDenominatorGapMin,
71 : FractionDenomDisplayStyleGapMin,
72 : SkewedFractionHorizontalGap,
73 : SkewedFractionVerticalGap,
74 : OverbarVerticalGap,
75 : OverbarRuleThickness,
76 : OverbarExtraAscender,
77 : UnderbarVerticalGap,
78 : UnderbarRuleThickness,
79 : UnderbarExtraDescender,
80 : RadicalVerticalGap,
81 : RadicalDisplayStyleVerticalGap,
82 : RadicalRuleThickness,
83 : RadicalExtraAscender,
84 : RadicalKernBeforeDegree,
85 : RadicalKernAfterDegree,
86 : RadicalDegreeBottomRaisePercent
87 : };
88 :
89 : /**
90 : * Returns the value of the specified constant from the MATH table.
91 : */
92 : gfxFloat Constant(MathConstant aConstant) const;
93 :
94 : /**
95 : * Returns the value of the specified constant in app units.
96 : */
97 0 : nscoord Constant(MathConstant aConstant,
98 : uint32_t aAppUnitsPerDevPixel) const
99 : {
100 0 : return NSToCoordRound(Constant(aConstant) * aAppUnitsPerDevPixel);
101 : }
102 :
103 : /**
104 : * If the MATH table contains an italic correction for that glyph, this
105 : * function returns the corresponding value. Otherwise it returns 0.
106 : */
107 : gfxFloat
108 : ItalicsCorrection(uint32_t aGlyphID) const;
109 :
110 : /**
111 : * @param aGlyphID glyph index of the character we want to stretch
112 : * @param aVertical direction of the stretching (vertical/horizontal)
113 : * @param aSize the desired size variant
114 : *
115 : * Returns the glyph index of the desired size variant or 0 if there is not
116 : * any such size variant.
117 : */
118 : uint32_t VariantsSize(uint32_t aGlyphID, bool aVertical,
119 : uint16_t aSize) const;
120 :
121 : /**
122 : * @param aGlyphID glyph index of the character we want to stretch
123 : * @param aVertical direction of the stretching (vertical/horizontal)
124 : * @param aGlyphs pre-allocated buffer of 4 elements where the glyph
125 : * indexes (or 0 for absent parts) will be stored. The parts are stored in
126 : * the order expected by the nsMathMLChar: Top (or Left), Middle, Bottom
127 : * (or Right), Glue.
128 : *
129 : * Tries to fill-in aGlyphs with the relevant glyph indexes and returns
130 : * whether the operation was successful. The function returns false if
131 : * there is not any assembly for the character we want to stretch or if
132 : * the format is not supported by the nsMathMLChar code.
133 : *
134 : */
135 : bool VariantsParts(uint32_t aGlyphID, bool aVertical,
136 : uint32_t aGlyphs[4]) const;
137 :
138 : private:
139 : // size-specific font object, owned by the gfxMathTable
140 : hb_font_t *mHBFont;
141 :
142 : static const unsigned int kMaxCachedSizeCount = 10;
143 : struct MathVariantCacheEntry {
144 : uint32_t glyphID;
145 : bool vertical;
146 : uint32_t sizes[kMaxCachedSizeCount];
147 : uint32_t parts[4];
148 : bool arePartsValid;
149 : };
150 : mutable MathVariantCacheEntry mMathVariantCache;
151 : void ClearCache() const;
152 : void UpdateMathVariantCache(uint32_t aGlyphID, bool aVertical) const;
153 : };
154 :
155 : #endif
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