2 * Copyright © 2011,2012 Google, Inc.
4 * This is part of HarfBuzz, a text shaping library.
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.
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
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.
24 * Google Author(s): Behdad Esfahbod, Roderick Sheeter
27 #ifndef HB_OT_HMTX_TABLE_HH
28 #define HB_OT_HMTX_TABLE_HH
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 #include "hb-subset-plan.hh"
37 * hmtx -- Horizontal Metrics
38 * https://docs.microsoft.com/en-us/typography/opentype/spec/hmtx
39 * vmtx -- Vertical Metrics
40 * https://docs.microsoft.com/en-us/typography/opentype/spec/vmtx
42 #define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
43 #define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')
51 UFWORD advance; /* Advance width/height. */
52 FWORD lsb; /* Leading (left/top) side bearing. */
54 DEFINE_SIZE_STATIC (4);
57 template <typename T, typename H>
60 inline bool sanitize (hb_sanitize_context_t *c) const
62 TRACE_SANITIZE (this);
63 /* We don't check for anything specific here. The users of the
64 * struct do all the hard work... */
69 inline bool subset_update_header (hb_subset_plan_t *plan,
70 unsigned int num_hmetrics) const
72 hb_blob_t *src_blob = OT::Sanitizer<H> ().sanitize (plan->source->reference_table (H::tableTag));
73 hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail(src_blob);
74 hb_blob_destroy (src_blob);
76 if (unlikely (!dest_blob)) {
81 H *table = (H *) hb_blob_get_data (dest_blob, &length);
82 table->numberOfLongMetrics.set (num_hmetrics);
84 bool result = plan->add_table (H::tableTag, dest_blob);
85 hb_blob_destroy (dest_blob);
90 inline bool subset (hb_subset_plan_t *plan) const
92 typename T::accelerator_t _mtx;
93 _mtx.init (plan->source);
95 /* All the trailing glyphs with the same advance can use one LongMetric
96 * and just keep LSB */
97 hb_vector_t<hb_codepoint_t> &gids = plan->glyphs;
98 unsigned int num_advances = gids.len;
99 unsigned int last_advance = _mtx.get_advance (gids[num_advances - 1]);
100 while (num_advances > 1
101 && last_advance == _mtx.get_advance (gids[num_advances - 2]))
106 /* alloc the new table */
107 size_t dest_sz = num_advances * 4
108 + (gids.len - num_advances) * 2;
109 void *dest = (void *) malloc (dest_sz);
110 if (unlikely (!dest))
114 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);
115 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);
117 const char *source_table = hb_blob_get_data (_mtx.blob, nullptr);
118 // Copy everything over
119 LongMetric * old_metrics = (LongMetric *) source_table;
120 FWORD *lsbs = (FWORD *) (old_metrics + _mtx.num_advances);
121 char * dest_pos = (char *) dest;
124 for (unsigned int i = 0; i < gids.len; i++)
126 /* the last metric or the one for gids[i] */
127 LongMetric *src_metric = old_metrics + MIN ((hb_codepoint_t) _mtx.num_advances - 1, gids[i]);
128 if (gids[i] < _mtx.num_advances)
130 /* src is a LongMetric */
131 if (i < num_advances)
133 /* dest is a LongMetric, copy it */
134 *((LongMetric *) dest_pos) = *src_metric;
139 *((FWORD *) dest_pos) = src_metric->lsb;
144 if (gids[i] >= _mtx.num_metrics)
146 DEBUG_MSG(SUBSET, nullptr, "gid %d is >= number of source metrics %d",
147 gids[i], _mtx.num_metrics);
151 FWORD src_lsb = *(lsbs + gids[i] - _mtx.num_advances);
152 if (i < num_advances)
154 /* dest needs a full LongMetric */
155 LongMetric *metric = (LongMetric *)dest_pos;
156 metric->advance = src_metric->advance;
157 metric->lsb = src_lsb;
161 /* dest just needs an lsb */
162 *((FWORD *) dest_pos) = src_lsb;
165 dest_pos += (i < num_advances ? 4 : 2);
169 // Amend header num hmetrics
170 if (failed || unlikely (!subset_update_header (plan, num_advances)))
176 hb_blob_t *result = hb_blob_create ((const char *)dest,
178 HB_MEMORY_MODE_READONLY,
181 bool success = plan->add_table (T::tableTag, result);
182 hb_blob_destroy (result);
188 friend struct hmtxvmtx;
190 inline void init (hb_face_t *face,
191 unsigned int default_advance_ = 0)
193 default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);
195 bool got_font_extents = false;
198 hb_blob_t *os2_blob = Sanitizer<os2> ().sanitize (face->reference_table (T::os2Tag));
199 const os2 *os2_table = os2_blob->as<os2> ();
200 #define USE_TYPO_METRICS (1u<<7)
201 if (0 != (os2_table->fsSelection & USE_TYPO_METRICS))
203 ascender = os2_table->sTypoAscender;
204 descender = os2_table->sTypoDescender;
205 line_gap = os2_table->sTypoLineGap;
206 got_font_extents = (ascender | descender) != 0;
208 hb_blob_destroy (os2_blob);
211 hb_blob_t *_hea_blob = Sanitizer<H> ().sanitize (face->reference_table (H::tableTag));
212 const H *_hea_table = _hea_blob->as<H> ();
213 num_advances = _hea_table->numberOfLongMetrics;
214 if (!got_font_extents)
216 ascender = _hea_table->ascender;
217 descender = _hea_table->descender;
218 line_gap = _hea_table->lineGap;
219 got_font_extents = (ascender | descender) != 0;
221 hb_blob_destroy (_hea_blob);
223 has_font_extents = got_font_extents;
225 blob = Sanitizer<hmtxvmtx> ().sanitize (face->reference_table (T::tableTag));
227 /* Cap num_metrics() and num_advances() based on table length. */
228 unsigned int len = hb_blob_get_length (blob);
229 if (unlikely (num_advances * 4 > len))
230 num_advances = len / 4;
231 num_metrics = num_advances + (len - 4 * num_advances) / 2;
233 /* We MUST set num_metrics to zero if num_advances is zero.
234 * Our get_advance() depends on that. */
235 if (unlikely (!num_advances))
237 num_metrics = num_advances = 0;
238 hb_blob_destroy (blob);
239 blob = hb_blob_get_empty ();
241 table = blob->as<hmtxvmtx> ();
243 var_blob = Sanitizer<HVARVVAR> ().sanitize (face->reference_table (T::variationsTag));
244 var_table = var_blob->as<HVARVVAR> ();
247 inline void fini (void)
249 hb_blob_destroy (blob);
250 hb_blob_destroy (var_blob);
253 inline unsigned int get_advance (hb_codepoint_t glyph) const
255 if (unlikely (glyph >= num_metrics))
257 /* If num_metrics is zero, it means we don't have the metrics table
258 * for this direction: return default advance. Otherwise, it means that the
259 * glyph index is out of bound: return zero. */
263 return default_advance;
266 return table->longMetric[MIN (glyph, (uint32_t) num_advances - 1)].advance;
269 inline unsigned int get_advance (hb_codepoint_t glyph,
270 hb_font_t *font) const
272 unsigned int advance = get_advance (glyph);
273 if (likely(glyph < num_metrics))
275 advance += (font->num_coords ? var_table->get_advance_var (glyph, font->coords, font->num_coords) : 0); // TODO Optimize?!
281 bool has_font_extents;
282 unsigned short ascender;
283 unsigned short descender;
284 unsigned short line_gap;
287 unsigned int num_metrics;
288 unsigned int num_advances;
289 unsigned int default_advance;
292 const hmtxvmtx *table;
294 const HVARVVAR *var_table;
299 LongMetric longMetric[VAR]; /* Paired advance width and leading
300 * bearing values for each glyph. The
301 * value numOfHMetrics comes from
302 * the 'hhea' table. If the font is
303 * monospaced, only one entry need
304 * be in the array, but that entry is
305 * required. The last entry applies to
306 * all subsequent glyphs. */
307 /*FWORD leadingBearingX[VAR];*/ /* Here the advance is assumed
308 * to be the same as the advance
309 * for the last entry above. The
310 * number of entries in this array is
311 * derived from numGlyphs (from 'maxp'
312 * table) minus numberOfLongMetrics.
313 * This generally is used with a run
314 * of monospaced glyphs (e.g., Kanji
315 * fonts or Courier fonts). Only one
316 * run is allowed and it must be at
317 * the end. This allows a monospaced
318 * font to vary the side bearing
319 * values for each glyph. */
321 DEFINE_SIZE_ARRAY (0, longMetric);
324 struct hmtx : hmtxvmtx<hmtx, hhea> {
325 static const hb_tag_t tableTag = HB_OT_TAG_hmtx;
326 static const hb_tag_t variationsTag = HB_OT_TAG_HVAR;
327 static const hb_tag_t os2Tag = HB_OT_TAG_os2;
329 struct vmtx : hmtxvmtx<vmtx, vhea> {
330 static const hb_tag_t tableTag = HB_OT_TAG_vmtx;
331 static const hb_tag_t variationsTag = HB_OT_TAG_VVAR;
332 static const hb_tag_t os2Tag = HB_TAG_NONE;
338 #endif /* HB_OT_HMTX_TABLE_HH */