1 | /* |
2 | * Copyright © 2011,2012 Google, Inc. |
3 | * |
4 | * This is part of HarfBuzz, a text shaping library. |
5 | * |
6 | * Permission is hereby granted, without written agreement and without |
7 | * license or royalty fees, to use, copy, modify, and distribute this |
8 | * software and its documentation for any purpose, provided that the |
9 | * above copyright notice and the following two paragraphs appear in |
10 | * all copies of this software. |
11 | * |
12 | * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR |
13 | * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES |
14 | * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN |
15 | * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH |
16 | * DAMAGE. |
17 | * |
18 | * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, |
19 | * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND |
20 | * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS |
21 | * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO |
22 | * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. |
23 | * |
24 | * Google Author(s): Behdad Esfahbod |
25 | */ |
26 | |
27 | #ifndef HB_OT_HMTX_TABLE_HH |
28 | #define HB_OT_HMTX_TABLE_HH |
29 | |
30 | #include "hb-open-type-private.hh" |
31 | #include "hb-ot-hhea-table.hh" |
32 | #include "hb-ot-os2-table.hh" |
33 | #include "hb-ot-var-hvar-table.hh" |
34 | |
35 | |
36 | namespace OT { |
37 | |
38 | |
39 | /* |
40 | * hmtx -- The Horizontal Metrics Table |
41 | * vmtx -- The Vertical Metrics Table |
42 | */ |
43 | |
44 | #define HB_OT_TAG_hmtx HB_TAG('h','m','t','x') |
45 | #define HB_OT_TAG_vmtx HB_TAG('v','m','t','x') |
46 | |
47 | |
48 | struct LongMetric |
49 | { |
50 | UFWORD advance; /* Advance width/height. */ |
51 | FWORD lsb; /* Leading (left/top) side bearing. */ |
52 | public: |
53 | DEFINE_SIZE_STATIC (4); |
54 | }; |
55 | |
56 | template <typename T> |
57 | struct hmtxvmtx |
58 | { |
59 | inline bool sanitize (hb_sanitize_context_t *c) const |
60 | { |
61 | TRACE_SANITIZE (this); |
62 | /* We don't check for anything specific here. The users of the |
63 | * struct do all the hard work... */ |
64 | return_trace (true); |
65 | } |
66 | |
67 | struct accelerator_t |
68 | { |
69 | inline void init (hb_face_t *face, |
70 | unsigned int default_advance_ = 0) |
71 | { |
72 | default_advance = default_advance_ ? default_advance_ : face->get_upem (); |
73 | |
74 | bool got_font_extents = false; |
75 | if (T::os2Tag) |
76 | { |
77 | hb_blob_t *os2_blob = Sanitizer<os2>::sanitize (blob: face->reference_table (tag: T::os2Tag)); |
78 | const os2 *os2_table = Sanitizer<os2>::lock_instance (blob: os2_blob); |
79 | #define USE_TYPO_METRICS (1u<<7) |
80 | if (0 != (os2_table->fsSelection & USE_TYPO_METRICS)) |
81 | { |
82 | ascender = os2_table->sTypoAscender; |
83 | descender = os2_table->sTypoDescender; |
84 | line_gap = os2_table->sTypoLineGap; |
85 | got_font_extents = (ascender | descender) != 0; |
86 | } |
87 | hb_blob_destroy (blob: os2_blob); |
88 | } |
89 | |
90 | hb_blob_t *_hea_blob = Sanitizer<_hea>::sanitize (blob: face->reference_table (tag: T::headerTag)); |
91 | const _hea *_hea_table = Sanitizer<_hea>::lock_instance (blob: _hea_blob); |
92 | num_advances = _hea_table->numberOfLongMetrics; |
93 | if (!got_font_extents) |
94 | { |
95 | ascender = _hea_table->ascender; |
96 | descender = _hea_table->descender; |
97 | line_gap = _hea_table->lineGap; |
98 | got_font_extents = (ascender | descender) != 0; |
99 | } |
100 | hb_blob_destroy (blob: _hea_blob); |
101 | |
102 | has_font_extents = got_font_extents; |
103 | |
104 | blob = Sanitizer<hmtxvmtx>::sanitize (face->reference_table (tag: T::tableTag)); |
105 | |
106 | /* Cap num_metrics() and num_advances() based on table length. */ |
107 | unsigned int len = hb_blob_get_length (blob); |
108 | if (unlikely (num_advances * 4 > len)) |
109 | num_advances = len / 4; |
110 | num_metrics = num_advances + (len - 4 * num_advances) / 2; |
111 | |
112 | /* We MUST set num_metrics to zero if num_advances is zero. |
113 | * Our get_advance() depends on that. */ |
114 | if (unlikely (!num_advances)) |
115 | { |
116 | num_metrics = num_advances = 0; |
117 | hb_blob_destroy (blob); |
118 | blob = hb_blob_get_empty (); |
119 | } |
120 | table = Sanitizer<hmtxvmtx>::lock_instance (blob); |
121 | |
122 | var_blob = Sanitizer<HVARVVAR>::sanitize (blob: face->reference_table (tag: T::variationsTag)); |
123 | var_table = Sanitizer<HVARVVAR>::lock_instance (blob: var_blob); |
124 | } |
125 | |
126 | inline void fini (void) |
127 | { |
128 | hb_blob_destroy (blob); |
129 | hb_blob_destroy (blob: var_blob); |
130 | } |
131 | |
132 | inline unsigned int get_advance (hb_codepoint_t glyph, |
133 | hb_font_t *font) const |
134 | { |
135 | if (unlikely (glyph >= num_metrics)) |
136 | { |
137 | /* If num_metrics is zero, it means we don't have the metrics table |
138 | * for this direction: return default advance. Otherwise, it means that the |
139 | * glyph index is out of bound: return zero. */ |
140 | if (num_metrics) |
141 | return 0; |
142 | else |
143 | return default_advance; |
144 | } |
145 | |
146 | return table->longMetric[MIN (a: glyph, b: (uint32_t) num_advances - 1)].advance |
147 | + var_table->get_advance_var (glyph, coords: font->coords, coord_count: font->num_coords); // TODO Optimize?! |
148 | } |
149 | |
150 | public: |
151 | bool has_font_extents; |
152 | unsigned short ascender; |
153 | unsigned short descender; |
154 | unsigned short line_gap; |
155 | |
156 | private: |
157 | unsigned int num_metrics; |
158 | unsigned int num_advances; |
159 | unsigned int default_advance; |
160 | |
161 | const hmtxvmtx *table; |
162 | hb_blob_t *blob; |
163 | const HVARVVAR *var_table; |
164 | hb_blob_t *var_blob; |
165 | }; |
166 | |
167 | protected: |
168 | LongMetric longMetric[VAR]; /* Paired advance width and leading |
169 | * bearing values for each glyph. The |
170 | * value numOfHMetrics comes from |
171 | * the 'hhea' table. If the font is |
172 | * monospaced, only one entry need |
173 | * be in the array, but that entry is |
174 | * required. The last entry applies to |
175 | * all subsequent glyphs. */ |
176 | FWORD leadingBearingX[VAR]; /* Here the advance is assumed |
177 | * to be the same as the advance |
178 | * for the last entry above. The |
179 | * number of entries in this array is |
180 | * derived from numGlyphs (from 'maxp' |
181 | * table) minus numberOfLongMetrics. |
182 | * This generally is used with a run |
183 | * of monospaced glyphs (e.g., Kanji |
184 | * fonts or Courier fonts). Only one |
185 | * run is allowed and it must be at |
186 | * the end. This allows a monospaced |
187 | * font to vary the side bearing |
188 | * values for each glyph. */ |
189 | public: |
190 | DEFINE_SIZE_ARRAY2 (0, longMetric, leadingBearingX); |
191 | }; |
192 | |
193 | struct hmtx : hmtxvmtx<hmtx> { |
194 | static const hb_tag_t tableTag = HB_OT_TAG_hmtx; |
195 | static const hb_tag_t = HB_OT_TAG_hhea; |
196 | static const hb_tag_t variationsTag = HB_OT_TAG_HVAR; |
197 | static const hb_tag_t os2Tag = HB_OT_TAG_os2; |
198 | }; |
199 | struct vmtx : hmtxvmtx<vmtx> { |
200 | static const hb_tag_t tableTag = HB_OT_TAG_vmtx; |
201 | static const hb_tag_t = HB_OT_TAG_vhea; |
202 | static const hb_tag_t variationsTag = HB_OT_TAG_VVAR; |
203 | static const hb_tag_t os2Tag = HB_TAG_NONE; |
204 | }; |
205 | |
206 | } /* namespace OT */ |
207 | |
208 | |
209 | #endif /* HB_OT_HMTX_TABLE_HH */ |
210 | |