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.hh"
31 #include "hb-ot-hhea-table.hh"
32 #include "hb-ot-os2-table.hh"
33 #include "hb-ot-var-hvar-table.hh"
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
41 #define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
42 #define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')
50 UFWORD advance; /* Advance width/height. */
51 FWORD sb; /* Leading (left/top) side bearing. */
53 DEFINE_SIZE_STATIC (4);
56 template <typename T, typename H>
59 bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
61 TRACE_SANITIZE (this);
62 /* We don't check for anything specific here. The users of the
63 * struct do all the hard work... */
68 bool subset_update_header (hb_subset_plan_t *plan,
69 unsigned int num_hmetrics) const
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);
75 if (unlikely (!dest_blob)) {
80 H *table = (H *) hb_blob_get_data (dest_blob, &length);
81 table->numberOfLongMetrics.set (num_hmetrics);
83 bool result = plan->add_table (H::tableTag, dest_blob);
84 hb_blob_destroy (dest_blob);
89 bool subset (hb_subset_plan_t *plan) const
91 typename T::accelerator_t _mtx;
92 _mtx.init (plan->source);
94 /* All the trailing glyphs with the same advance can use one LongMetric
95 * and just keep LSB */
96 unsigned int num_output_glyphs = plan->num_output_glyphs ();
97 unsigned int num_advances = _mtx.num_advances_for_subset (plan);
99 /* alloc the new table */
100 size_t dest_sz = num_advances * 4
101 + (num_output_glyphs - num_advances) * 2;
102 void *dest = (void *) malloc (dest_sz);
103 if (unlikely (!dest))
107 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);
108 DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in dest has %d advances, %d lsbs, %u bytes",
109 HB_UNTAG(T::tableTag), num_advances, num_output_glyphs - num_advances, (unsigned int) dest_sz);
111 // Copy everything over
112 char * dest_pos = (char *) dest;
115 for (unsigned int i = 0; i < num_output_glyphs; i++)
117 unsigned int side_bearing = 0;
118 unsigned int advance = 0;
119 hb_codepoint_t old_gid;
120 if (plan->old_gid_for_new_gid (i, &old_gid))
122 // Glyph is not an empty glyph so copy advance and side bearing
123 // from the input font.
124 side_bearing = _mtx.get_side_bearing (old_gid);
125 advance = _mtx.get_advance (old_gid);
128 bool has_advance = i < num_advances;
131 ((LongMetric *) dest_pos)->advance.set (advance);
132 ((LongMetric *) dest_pos)->sb.set (side_bearing);
136 ((FWORD *) dest_pos)->set (side_bearing);
138 dest_pos += (has_advance ? 4 : 2);
142 // Amend header num hmetrics
143 if (failed || unlikely (!subset_update_header (plan, num_advances)))
149 hb_blob_t *result = hb_blob_create ((const char *)dest,
151 HB_MEMORY_MODE_READONLY,
154 bool success = plan->add_table (T::tableTag, result);
155 hb_blob_destroy (result);
161 friend struct hmtxvmtx;
163 void init (hb_face_t *face,
164 unsigned int default_advance_ = 0)
166 default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);
168 bool got_font_extents = false;
169 if (T::os2Tag != HB_TAG_NONE && face->table.OS2->is_typo_metrics ())
171 ascender = abs (face->table.OS2->sTypoAscender);
172 descender = -abs (face->table.OS2->sTypoDescender);
173 line_gap = face->table.OS2->sTypoLineGap;
174 got_font_extents = (ascender | descender) != 0;
177 hb_blob_t *_hea_blob = hb_sanitize_context_t().reference_table<H> (face);
178 const H *_hea_table = _hea_blob->as<H> ();
179 num_advances = _hea_table->numberOfLongMetrics;
180 if (!got_font_extents)
182 ascender = abs (_hea_table->ascender);
183 descender = -abs (_hea_table->descender);
184 line_gap = _hea_table->lineGap;
185 got_font_extents = (ascender | descender) != 0;
187 hb_blob_destroy (_hea_blob);
189 has_font_extents = got_font_extents;
191 table = hb_sanitize_context_t().reference_table<hmtxvmtx> (face, T::tableTag);
193 /* Cap num_metrics() and num_advances() based on table length. */
194 unsigned int len = table.get_length ();
195 if (unlikely (num_advances * 4 > len))
196 num_advances = len / 4;
197 num_metrics = num_advances + (len - 4 * num_advances) / 2;
199 /* We MUST set num_metrics to zero if num_advances is zero.
200 * Our get_advance() depends on that. */
201 if (unlikely (!num_advances))
203 num_metrics = num_advances = 0;
205 table = hb_blob_get_empty ();
208 var_table = hb_sanitize_context_t().reference_table<HVARVVAR> (face, T::variationsTag);
214 var_table.destroy ();
217 /* TODO Add variations version. */
218 unsigned int get_side_bearing (hb_codepoint_t glyph) const
220 if (glyph < num_advances)
221 return table->longMetricZ[glyph].sb;
223 if (unlikely (glyph >= num_metrics))
226 const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_advances];
227 return bearings[glyph - num_advances];
230 unsigned int get_advance (hb_codepoint_t glyph) const
232 if (unlikely (glyph >= num_metrics))
234 /* If num_metrics is zero, it means we don't have the metrics table
235 * for this direction: return default advance. Otherwise, it means that the
236 * glyph index is out of bound: return zero. */
240 return default_advance;
243 return table->longMetricZ[MIN (glyph, (uint32_t) num_advances - 1)].advance;
246 unsigned int get_advance (hb_codepoint_t glyph,
247 hb_font_t *font) const
249 unsigned int advance = get_advance (glyph);
250 if (likely (glyph < num_metrics))
252 advance += (font->num_coords ? var_table->get_advance_var (glyph, font->coords, font->num_coords) : 0); // TODO Optimize?!
257 unsigned int num_advances_for_subset (const hb_subset_plan_t *plan) const
259 unsigned int num_advances = plan->num_output_glyphs ();
260 unsigned int last_advance = _advance_for_new_gid (plan,
262 while (num_advances > 1 &&
263 last_advance == _advance_for_new_gid (plan,
273 unsigned int _advance_for_new_gid (const hb_subset_plan_t *plan,
274 hb_codepoint_t new_gid) const
276 hb_codepoint_t old_gid;
277 if (!plan->old_gid_for_new_gid (new_gid, &old_gid))
280 return get_advance (old_gid);
284 bool has_font_extents;
290 unsigned int num_metrics;
291 unsigned int num_advances;
292 unsigned int default_advance;
295 hb_blob_ptr_t<hmtxvmtx> table;
296 hb_blob_ptr_t<HVARVVAR> var_table;
300 UnsizedArrayOf<LongMetric>longMetricZ;/* Paired advance width and leading
301 * bearing values for each glyph. The
302 * value numOfHMetrics comes from
303 * the 'hhea' table. If the font is
304 * monospaced, only one entry need
305 * be in the array, but that entry is
306 * required. The last entry applies to
307 * all subsequent glyphs. */
308 /*UnsizedArrayOf<FWORD> leadingBearingX;*//* Here the advance is assumed
309 * to be the same as the advance
310 * for the last entry above. The
311 * number of entries in this array is
312 * derived from numGlyphs (from 'maxp'
313 * table) minus numberOfLongMetrics.
314 * This generally is used with a run
315 * of monospaced glyphs (e.g., Kanji
316 * fonts or Courier fonts). Only one
317 * run is allowed and it must be at
318 * the end. This allows a monospaced
319 * font to vary the side bearing
320 * values for each glyph. */
322 DEFINE_SIZE_ARRAY (0, longMetricZ);
325 struct hmtx : hmtxvmtx<hmtx, hhea> {
326 static constexpr hb_tag_t tableTag = HB_OT_TAG_hmtx;
327 static constexpr hb_tag_t variationsTag = HB_OT_TAG_HVAR;
328 static constexpr hb_tag_t os2Tag = HB_OT_TAG_OS2;
330 struct vmtx : hmtxvmtx<vmtx, vhea> {
331 static constexpr hb_tag_t tableTag = HB_OT_TAG_vmtx;
332 static constexpr hb_tag_t variationsTag = HB_OT_TAG_VVAR;
333 static constexpr hb_tag_t os2Tag = HB_TAG_NONE;
336 struct hmtx_accelerator_t : hmtx::accelerator_t {};
337 struct vmtx_accelerator_t : vmtx::accelerator_t {};
342 #endif /* HB_OT_HMTX_TABLE_HH */