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-var-hvar-table.hh"
33#include "hb-ot-metrics.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
45HB_INTERNAL int
46_glyf_get_side_bearing_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);
47
48HB_INTERNAL unsigned
49_glyf_get_advance_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);
50
51
52namespace OT {
53
54
55struct LongMetric
56{
57 UFWORD advance; /* Advance width/height. */
58 FWORD sb; /* Leading (left/top) side bearing. */
59 public:
60 DEFINE_SIZE_STATIC (4);
61};
62
63
64template <typename T, typename H>
65struct hmtxvmtx
66{
67 bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
68 {
69 TRACE_SANITIZE (this);
70 /* We don't check for anything specific here. The users of the
71 * struct do all the hard work... */
72 return_trace (true);
73 }
74
75
76 bool subset_update_header (hb_subset_plan_t *plan,
77 unsigned int num_hmetrics) const
78 {
79 hb_blob_t *src_blob = hb_sanitize_context_t ().reference_table<H> (plan->source, H::tableTag);
80 hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail (src_blob);
81 hb_blob_destroy (src_blob);
82
83 if (unlikely (!dest_blob)) {
84 return false;
85 }
86
87 unsigned int length;
88 H *table = (H *) hb_blob_get_data (dest_blob, &length);
89 table->numberOfLongMetrics = num_hmetrics;
90
91 bool result = plan->add_table (H::tableTag, dest_blob);
92 hb_blob_destroy (dest_blob);
93
94 return result;
95 }
96
97 template<typename Iterator,
98 hb_requires (hb_is_iterator (Iterator))>
99 void serialize (hb_serialize_context_t *c,
100 Iterator it,
101 unsigned num_advances)
102 {
103 unsigned idx = 0;
104 for (auto _ : it)
105 {
106 if (idx < num_advances)
107 {
108 LongMetric lm;
109 lm.advance = _.first;
110 lm.sb = _.second;
111 if (unlikely (!c->embed<LongMetric> (&lm))) return;
112 }
113 else
114 {
115 FWORD *sb = c->allocate_size<FWORD> (FWORD::static_size);
116 if (unlikely (!sb)) return;
117 *sb = _.second;
118 }
119 idx++;
120 }
121 }
122
123 bool subset (hb_subset_context_t *c) const
124 {
125 TRACE_SUBSET (this);
126
127 T *table_prime = c->serializer->start_embed <T> ();
128 if (unlikely (!table_prime)) return_trace (false);
129
130 accelerator_t _mtx;
131 _mtx.init (c->plan->source);
132 unsigned num_advances = _mtx.num_advances_for_subset (c->plan);
133
134 auto it =
135 + hb_range (c->plan->num_output_glyphs ())
136 | hb_map ([c, &_mtx] (unsigned _)
137 {
138 hb_codepoint_t old_gid;
139 if (!c->plan->old_gid_for_new_gid (_, &old_gid))
140 return hb_pair (0u, 0);
141 return hb_pair (_mtx.get_advance (old_gid), _mtx.get_side_bearing (old_gid));
142 })
143 ;
144
145 table_prime->serialize (c->serializer, it, num_advances);
146
147 _mtx.fini ();
148
149 if (unlikely (c->serializer->ran_out_of_room || c->serializer->in_error ()))
150 return_trace (false);
151
152 // Amend header num hmetrics
153 if (unlikely (!subset_update_header (c->plan, num_advances)))
154 return_trace (false);
155
156 return_trace (true);
157 }
158
159 struct accelerator_t
160 {
161 friend struct hmtxvmtx;
162
163 void init (hb_face_t *face,
164 unsigned int default_advance_ = 0)
165 {
166 default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);
167
168 num_advances = T::is_horizontal ? face->table.hhea->numberOfLongMetrics : face->table.vhea->numberOfLongMetrics;
169
170 table = hb_sanitize_context_t ().reference_table<hmtxvmtx> (face, T::tableTag);
171
172 /* Cap num_metrics() and num_advances() based on table length. */
173 unsigned int len = table.get_length ();
174 if (unlikely (num_advances * 4 > len))
175 num_advances = len / 4;
176 num_metrics = num_advances + (len - 4 * num_advances) / 2;
177
178 /* We MUST set num_metrics to zero if num_advances is zero.
179 * Our get_advance() depends on that. */
180 if (unlikely (!num_advances))
181 {
182 num_metrics = num_advances = 0;
183 table.destroy ();
184 table = hb_blob_get_empty ();
185 }
186
187 var_table = hb_sanitize_context_t ().reference_table<HVARVVAR> (face, T::variationsTag);
188 }
189
190 void fini ()
191 {
192 table.destroy ();
193 var_table.destroy ();
194 }
195
196 int get_side_bearing (hb_codepoint_t glyph) const
197 {
198 if (glyph < num_advances)
199 return table->longMetricZ[glyph].sb;
200
201 if (unlikely (glyph >= num_metrics))
202 return 0;
203
204 const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_advances];
205 return bearings[glyph - num_advances];
206 }
207
208 int get_side_bearing (hb_font_t *font, hb_codepoint_t glyph) const
209 {
210 int side_bearing = get_side_bearing (glyph);
211
212#ifndef HB_NO_VAR
213 if (unlikely (glyph >= num_metrics) || !font->num_coords)
214 return side_bearing;
215
216 if (var_table.get_length ())
217 return side_bearing + var_table->get_side_bearing_var (glyph, font->coords, font->num_coords); // TODO Optimize?!
218
219 return _glyf_get_side_bearing_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
220#else
221 return side_bearing;
222#endif
223 }
224
225 unsigned int get_advance (hb_codepoint_t glyph) const
226 {
227 if (unlikely (glyph >= num_metrics))
228 {
229 /* If num_metrics is zero, it means we don't have the metrics table
230 * for this direction: return default advance. Otherwise, it means that the
231 * glyph index is out of bound: return zero. */
232 if (num_metrics)
233 return 0;
234 else
235 return default_advance;
236 }
237
238 return table->longMetricZ[hb_min (glyph, (uint32_t) num_advances - 1)].advance;
239 }
240
241 unsigned int get_advance (hb_codepoint_t glyph,
242 hb_font_t *font) const
243 {
244 unsigned int advance = get_advance (glyph);
245
246#ifndef HB_NO_VAR
247 if (unlikely (glyph >= num_metrics) || !font->num_coords)
248 return advance;
249
250 if (var_table.get_length ())
251 return advance + roundf (var_table->get_advance_var (glyph, font)); // TODO Optimize?!
252
253 return _glyf_get_advance_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
254#else
255 return advance;
256#endif
257 }
258
259 unsigned int num_advances_for_subset (const hb_subset_plan_t *plan) const
260 {
261 unsigned int num_advances = plan->num_output_glyphs ();
262 unsigned int last_advance = _advance_for_new_gid (plan,
263 num_advances - 1);
264 while (num_advances > 1 &&
265 last_advance == _advance_for_new_gid (plan,
266 num_advances - 2))
267 {
268 num_advances--;
269 }
270
271 return num_advances;
272 }
273
274 private:
275 unsigned int _advance_for_new_gid (const hb_subset_plan_t *plan,
276 hb_codepoint_t new_gid) const
277 {
278 hb_codepoint_t old_gid;
279 if (!plan->old_gid_for_new_gid (new_gid, &old_gid))
280 return 0;
281
282 return get_advance (old_gid);
283 }
284
285 protected:
286 unsigned int num_metrics;
287 unsigned int num_advances;
288 unsigned int default_advance;
289
290 private:
291 hb_blob_ptr_t<hmtxvmtx> table;
292 hb_blob_ptr_t<HVARVVAR> var_table;
293 };
294
295 protected:
296 UnsizedArrayOf<LongMetric>
297 longMetricZ; /* Paired advance width and leading
298 * bearing values for each glyph. The
299 * value numOfHMetrics comes from
300 * the 'hhea' table. If the font is
301 * monospaced, only one entry need
302 * be in the array, but that entry is
303 * required. The last entry applies to
304 * all subsequent glyphs. */
305/*UnsizedArrayOf<FWORD> leadingBearingX;*/
306 /* 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, longMetricZ);
321};
322
323struct hmtx : hmtxvmtx<hmtx, hhea> {
324 static constexpr hb_tag_t tableTag = HB_OT_TAG_hmtx;
325 static constexpr hb_tag_t variationsTag = HB_OT_TAG_HVAR;
326 static constexpr bool is_horizontal = true;
327};
328struct vmtx : hmtxvmtx<vmtx, vhea> {
329 static constexpr hb_tag_t tableTag = HB_OT_TAG_vmtx;
330 static constexpr hb_tag_t variationsTag = HB_OT_TAG_VVAR;
331 static constexpr bool is_horizontal = false;
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