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, Roderick Sheeter
25 */
26
27#ifndef HB_OT_HMTX_TABLE_HH
28#define HB_OT_HMTX_TABLE_HH
29
30#include "hb-open-type.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 * hmtx -- Horizontal Metrics
37 * https://docs.microsoft.com/en-us/typography/opentype/spec/hmtx
38 * vmtx -- Vertical Metrics
39 * https://docs.microsoft.com/en-us/typography/opentype/spec/vmtx
40 */
41#define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
42#define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')
43
44
45namespace OT {
46
47
48struct 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
56template <typename T, typename H>
57struct 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
68 inline bool subset_update_header (hb_subset_plan_t *plan,
69 unsigned int num_hmetrics) const
70 {
71 hb_blob_t *src_blob = hb_sanitize_context_t().reference_table<H> (plan->source, H::tableTag);
72 hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail(src_blob);
73 hb_blob_destroy (src_blob);
74
75 if (unlikely (!dest_blob)) {
76 return false;
77 }
78
79 unsigned int length;
80 H *table = (H *) hb_blob_get_data (dest_blob, &length);
81 table->numberOfLongMetrics.set (num_hmetrics);
82
83 bool result = plan->add_table (H::tableTag, dest_blob);
84 hb_blob_destroy (dest_blob);
85
86 return result;
87 }
88
89 inline bool subset (hb_subset_plan_t *plan) const
90 {
91 typename T::accelerator_t _mtx;
92 _mtx.init (plan->source);
93
94 /* All the trailing glyphs with the same advance can use one LongMetric
95 * and just keep LSB */
96 hb_vector_t<hb_codepoint_t> &gids = plan->glyphs;
97 unsigned int num_advances = gids.len;
98 unsigned int last_advance = _mtx.get_advance (gids[num_advances - 1]);
99 while (num_advances > 1
100 && last_advance == _mtx.get_advance (gids[num_advances - 2]))
101 {
102 num_advances--;
103 }
104
105 /* alloc the new table */
106 size_t dest_sz = num_advances * 4
107 + (gids.len - num_advances) * 2;
108 void *dest = (void *) malloc (dest_sz);
109 if (unlikely (!dest))
110 {
111 return false;
112 }
113 DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in src has %d advances, %d lsbs", HB_UNTAG(T::tableTag), _mtx.num_advances, _mtx.num_metrics - _mtx.num_advances);
114 DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in dest has %d advances, %d lsbs, %u bytes", HB_UNTAG(T::tableTag), num_advances, gids.len - num_advances, (unsigned int) dest_sz);
115
116 const char *source_table = hb_blob_get_data (_mtx.blob, nullptr);
117 // Copy everything over
118 LongMetric * old_metrics = (LongMetric *) source_table;
119 FWORD *lsbs = (FWORD *) (old_metrics + _mtx.num_advances);
120 char * dest_pos = (char *) dest;
121
122 bool failed = false;
123 for (unsigned int i = 0; i < gids.len; i++)
124 {
125 /* the last metric or the one for gids[i] */
126 LongMetric *src_metric = old_metrics + MIN ((hb_codepoint_t) _mtx.num_advances - 1, gids[i]);
127 if (gids[i] < _mtx.num_advances)
128 {
129 /* src is a LongMetric */
130 if (i < num_advances)
131 {
132 /* dest is a LongMetric, copy it */
133 *((LongMetric *) dest_pos) = *src_metric;
134 }
135 else
136 {
137 /* dest just lsb */
138 *((FWORD *) dest_pos) = src_metric->lsb;
139 }
140 }
141 else
142 {
143 if (gids[i] >= _mtx.num_metrics)
144 {
145 DEBUG_MSG(SUBSET, nullptr, "gid %d is >= number of source metrics %d",
146 gids[i], _mtx.num_metrics);
147 failed = true;
148 break;
149 }
150 FWORD src_lsb = *(lsbs + gids[i] - _mtx.num_advances);
151 if (i < num_advances)
152 {
153 /* dest needs a full LongMetric */
154 LongMetric *metric = (LongMetric *)dest_pos;
155 metric->advance = src_metric->advance;
156 metric->lsb = src_lsb;
157 }
158 else
159 {
160 /* dest just needs an lsb */
161 *((FWORD *) dest_pos) = src_lsb;
162 }
163 }
164 dest_pos += (i < num_advances ? 4 : 2);
165 }
166 _mtx.fini ();
167
168 // Amend header num hmetrics
169 if (failed || unlikely (!subset_update_header (plan, num_advances)))
170 {
171 free (dest);
172 return false;
173 }
174
175 hb_blob_t *result = hb_blob_create ((const char *)dest,
176 dest_sz,
177 HB_MEMORY_MODE_READONLY,
178 dest,
179 free);
180 bool success = plan->add_table (T::tableTag, result);
181 hb_blob_destroy (result);
182 return success;
183 }
184
185 struct accelerator_t
186 {
187 friend struct hmtxvmtx;
188
189 inline void init (hb_face_t *face,
190 unsigned int default_advance_ = 0)
191 {
192 default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);
193
194 bool got_font_extents = false;
195 if (T::os2Tag)
196 {
197 hb_blob_t *os2_blob = hb_sanitize_context_t().reference_table<os2> (face);
198 const os2 *os2_table = os2_blob->as<os2> ();
199#define USE_TYPO_METRICS (1u<<7)
200 if (0 != (os2_table->fsSelection & USE_TYPO_METRICS))
201 {
202 ascender = os2_table->sTypoAscender;
203 descender = os2_table->sTypoDescender;
204 line_gap = os2_table->sTypoLineGap;
205 got_font_extents = (ascender | descender) != 0;
206 }
207 hb_blob_destroy (os2_blob);
208 }
209
210 hb_blob_t *_hea_blob = hb_sanitize_context_t().reference_table<H> (face);
211 const H *_hea_table = _hea_blob->as<H> ();
212 num_advances = _hea_table->numberOfLongMetrics;
213 if (!got_font_extents)
214 {
215 ascender = _hea_table->ascender;
216 descender = _hea_table->descender;
217 line_gap = _hea_table->lineGap;
218 got_font_extents = (ascender | descender) != 0;
219 }
220 hb_blob_destroy (_hea_blob);
221
222 has_font_extents = got_font_extents;
223
224 blob = hb_sanitize_context_t().reference_table<hmtxvmtx> (face, T::tableTag);
225
226 /* Cap num_metrics() and num_advances() based on table length. */
227 unsigned int len = hb_blob_get_length (blob);
228 if (unlikely (num_advances * 4 > len))
229 num_advances = len / 4;
230 num_metrics = num_advances + (len - 4 * num_advances) / 2;
231
232 /* We MUST set num_metrics to zero if num_advances is zero.
233 * Our get_advance() depends on that. */
234 if (unlikely (!num_advances))
235 {
236 num_metrics = num_advances = 0;
237 hb_blob_destroy (blob);
238 blob = hb_blob_get_empty ();
239 }
240 table = blob->as<hmtxvmtx> ();
241
242 var_blob = hb_sanitize_context_t().reference_table<HVARVVAR> (face, T::variationsTag);
243 var_table = var_blob->as<HVARVVAR> ();
244 }
245
246 inline void fini (void)
247 {
248 hb_blob_destroy (blob);
249 hb_blob_destroy (var_blob);
250 }
251
252 inline unsigned int get_advance (hb_codepoint_t glyph) const
253 {
254 if (unlikely (glyph >= num_metrics))
255 {
256 /* If num_metrics is zero, it means we don't have the metrics table
257 * for this direction: return default advance. Otherwise, it means that the
258 * glyph index is out of bound: return zero. */
259 if (num_metrics)
260 return 0;
261 else
262 return default_advance;
263 }
264
265 return table->longMetric[MIN (glyph, (uint32_t) num_advances - 1)].advance;
266 }
267
268 inline unsigned int get_advance (hb_codepoint_t glyph,
269 hb_font_t *font) const
270 {
271 unsigned int advance = get_advance (glyph);
272 if (likely(glyph < num_metrics))
273 {
274 advance += (font->num_coords ? var_table->get_advance_var (glyph, font->coords, font->num_coords) : 0); // TODO Optimize?!
275 }
276 return advance;
277 }
278
279 public:
280 bool has_font_extents;
281 unsigned short ascender;
282 unsigned short descender;
283 unsigned short line_gap;
284
285 protected:
286 unsigned int num_metrics;
287 unsigned int num_advances;
288 unsigned int default_advance;
289
290 private:
291 const hmtxvmtx *table;
292 hb_blob_t *blob;
293 const HVARVVAR *var_table;
294 hb_blob_t *var_blob;
295 };
296
297 protected:
298 LongMetric longMetric[VAR]; /* Paired advance width and leading
299 * bearing values for each glyph. The
300 * value numOfHMetrics comes from
301 * the 'hhea' table. If the font is
302 * monospaced, only one entry need
303 * be in the array, but that entry is
304 * required. The last entry applies to
305 * all subsequent glyphs. */
306/*FWORD leadingBearingX[VAR];*/ /* Here the advance is assumed
307 * to be the same as the advance
308 * for the last entry above. The
309 * number of entries in this array is
310 * derived from numGlyphs (from 'maxp'
311 * table) minus numberOfLongMetrics.
312 * This generally is used with a run
313 * of monospaced glyphs (e.g., Kanji
314 * fonts or Courier fonts). Only one
315 * run is allowed and it must be at
316 * the end. This allows a monospaced
317 * font to vary the side bearing
318 * values for each glyph. */
319 public:
320 DEFINE_SIZE_ARRAY (0, longMetric);
321};
322
323struct hmtx : hmtxvmtx<hmtx, hhea> {
324 static const hb_tag_t tableTag = HB_OT_TAG_hmtx;
325 static const hb_tag_t variationsTag = HB_OT_TAG_HVAR;
326 static const hb_tag_t os2Tag = HB_OT_TAG_os2;
327};
328struct vmtx : hmtxvmtx<vmtx, vhea> {
329 static const hb_tag_t tableTag = HB_OT_TAG_vmtx;
330 static const hb_tag_t variationsTag = HB_OT_TAG_VVAR;
331 static const hb_tag_t os2Tag = HB_TAG_NONE;
332};
333
334struct hmtx_accelerator_t : hmtx::accelerator_t {};
335struct vmtx_accelerator_t : vmtx::accelerator_t {};
336
337} /* namespace OT */
338
339
340#endif /* HB_OT_HMTX_TABLE_HH */
341