1/*
2 * Copyright © 2018 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): Garret Rieger, Rod Sheeter, Behdad Esfahbod
25 */
26
27#include "hb.hh"
28#include "hb-open-type.hh"
29
30#include "hb-subset.hh"
31
32#include "hb-open-file.hh"
33#include "hb-ot-cmap-table.hh"
34#include "hb-ot-glyf-table.hh"
35#include "hb-ot-hdmx-table.hh"
36#include "hb-ot-head-table.hh"
37#include "hb-ot-hhea-table.hh"
38#include "hb-ot-hmtx-table.hh"
39#include "hb-ot-maxp-table.hh"
40#include "hb-ot-os2-table.hh"
41#include "hb-ot-post-table.hh"
42#include "hb-ot-cff1-table.hh"
43#include "hb-ot-cff2-table.hh"
44#include "hb-ot-vorg-table.hh"
45#include "hb-ot-name-table.hh"
46#include "hb-ot-layout-gsub-table.hh"
47#include "hb-ot-layout-gpos-table.hh"
48
49
50HB_UNUSED static inline unsigned int
51_plan_estimate_subset_table_size (hb_subset_plan_t *plan,
52 unsigned int table_len);
53static inline unsigned int
54_plan_estimate_subset_table_size (hb_subset_plan_t *plan,
55 unsigned int table_len)
56{
57 unsigned int src_glyphs = plan->source->get_num_glyphs ();
58 unsigned int dst_glyphs = plan->glyphset ()->get_population ();
59
60 if (unlikely (!src_glyphs))
61 return 512 + table_len;
62
63 return 512 + (unsigned int) (table_len * sqrt ((double) dst_glyphs / src_glyphs));
64}
65
66template<typename TableType>
67static bool
68_subset2 (hb_subset_plan_t *plan)
69{
70 bool result = false;
71 hb_blob_t *source_blob = hb_sanitize_context_t ().reference_table<TableType> (plan->source);
72 const TableType *table = source_blob->as<TableType> ();
73
74 hb_tag_t tag = TableType::tableTag;
75 if (source_blob->data)
76 {
77 hb_vector_t<char> buf;
78 /* TODO Not all tables are glyph-related. 'name' table size for example should not be
79 * affected by number of glyphs. Accommodate that. */
80 unsigned int buf_size = _plan_estimate_subset_table_size (plan, source_blob->length);
81 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c initial estimated table size: %u bytes.", HB_UNTAG (tag), buf_size);
82 if (unlikely (!buf.alloc (buf_size)))
83 {
84 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c failed to allocate %u bytes.", HB_UNTAG (tag), buf_size);
85 hb_blob_destroy (source_blob);
86 return false;
87 }
88 retry:
89 hb_serialize_context_t serializer ((void *) buf, buf_size);
90 serializer.start_serialize<TableType> ();
91 hb_subset_context_t c (plan, &serializer);
92 bool needed = table->subset (&c);
93 if (serializer.ran_out_of_room)
94 {
95 buf_size += (buf_size >> 1) + 32;
96 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c ran out of room; reallocating to %u bytes.", HB_UNTAG (tag), buf_size);
97 if (unlikely (!buf.alloc (buf_size)))
98 {
99 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c failed to reallocate %u bytes.", HB_UNTAG (tag), buf_size);
100 hb_blob_destroy (source_blob);
101 return false;
102 }
103 goto retry;
104 }
105 serializer.end_serialize ();
106
107 result = !serializer.in_error ();
108
109 if (result)
110 {
111 if (needed)
112 {
113 hb_blob_t *dest_blob = serializer.copy_blob ();
114 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c final subset table size: %u bytes.", HB_UNTAG (tag), dest_blob->length);
115 result = c.plan->add_table (tag, dest_blob);
116 hb_blob_destroy (dest_blob);
117 }
118 else
119 {
120 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset table subsetted to empty.", HB_UNTAG (tag));
121 }
122 }
123 }
124 else
125 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag));
126
127 hb_blob_destroy (source_blob);
128 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset %s", HB_UNTAG (tag), result ? "success" : "FAILED!");
129 return result;
130}
131
132template<typename TableType>
133static bool
134_subset (hb_subset_plan_t *plan)
135{
136 hb_blob_t *source_blob = hb_sanitize_context_t ().reference_table<TableType> (plan->source);
137 const TableType *table = source_blob->as<TableType> ();
138
139 hb_tag_t tag = TableType::tableTag;
140 hb_bool_t result = false;
141 if (source_blob->data)
142 result = table->subset (plan);
143 else
144 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag));
145
146 hb_blob_destroy (source_blob);
147 DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset %s", HB_UNTAG (tag), result ? "success" : "FAILED!");
148 return result;
149}
150
151
152static bool
153_subset_table (hb_subset_plan_t *plan,
154 hb_tag_t tag)
155{
156 DEBUG_MSG(SUBSET, nullptr, "begin subset %c%c%c%c", HB_UNTAG (tag));
157 bool result = true;
158 switch (tag) {
159 case HB_OT_TAG_glyf:
160 result = _subset2<const OT::glyf> (plan);
161 break;
162 case HB_OT_TAG_hdmx:
163 result = _subset2<const OT::hdmx> (plan);
164 break;
165 case HB_OT_TAG_name:
166 result = _subset2<const OT::name> (plan);
167 break;
168 case HB_OT_TAG_head:
169 // TODO that won't work well if there is no glyf
170 DEBUG_MSG(SUBSET, nullptr, "skip head, handled by glyf");
171 result = true;
172 break;
173 case HB_OT_TAG_hhea:
174 DEBUG_MSG(SUBSET, nullptr, "skip hhea handled by hmtx");
175 return true;
176 case HB_OT_TAG_hmtx:
177 result = _subset2<const OT::hmtx> (plan);
178 break;
179 case HB_OT_TAG_vhea:
180 DEBUG_MSG(SUBSET, nullptr, "skip vhea handled by vmtx");
181 return true;
182 case HB_OT_TAG_vmtx:
183 result = _subset2<const OT::vmtx> (plan);
184 break;
185 case HB_OT_TAG_maxp:
186 result = _subset2<const OT::maxp> (plan);
187 break;
188 case HB_OT_TAG_loca:
189 DEBUG_MSG(SUBSET, nullptr, "skip loca handled by glyf");
190 return true;
191 case HB_OT_TAG_cmap:
192 result = _subset2<const OT::cmap> (plan);
193 break;
194 case HB_OT_TAG_OS2:
195 result = _subset2<const OT::OS2> (plan);
196 break;
197 case HB_OT_TAG_post:
198 result = _subset2<const OT::post> (plan);
199 break;
200
201#ifndef HB_NO_SUBSET_CFF
202 case HB_OT_TAG_cff1:
203 result = _subset<const OT::cff1> (plan);
204 break;
205 case HB_OT_TAG_cff2:
206 result = _subset<const OT::cff2> (plan);
207 break;
208 case HB_OT_TAG_VORG:
209 result = _subset2<const OT::VORG> (plan);
210 break;
211#endif
212
213#ifndef HB_NO_SUBSET_LAYOUT
214 case HB_OT_TAG_GDEF:
215 result = _subset2<const OT::GDEF> (plan);
216 break;
217 case HB_OT_TAG_GSUB:
218 result = _subset2<const OT::GSUB> (plan);
219 break;
220 case HB_OT_TAG_GPOS:
221 result = _subset2<const OT::GPOS> (plan);
222 break;
223#endif
224
225 default:
226 hb_blob_t *source_table = hb_face_reference_table (plan->source, tag);
227 if (likely (source_table))
228 result = plan->add_table (tag, source_table);
229 else
230 result = false;
231 hb_blob_destroy (source_table);
232 break;
233 }
234 DEBUG_MSG(SUBSET, nullptr, "subset %c%c%c%c %s", HB_UNTAG (tag), result ? "ok" : "FAILED");
235 return result;
236}
237
238static bool
239_should_drop_table (hb_subset_plan_t *plan, hb_tag_t tag)
240{
241 if (plan->drop_tables->has (tag))
242 return true;
243
244 switch (tag) {
245 case HB_TAG ('c', 'v', 'a', 'r'): /* hint table, fallthrough */
246 case HB_TAG ('c', 'v', 't', ' '): /* hint table, fallthrough */
247 case HB_TAG ('f', 'p', 'g', 'm'): /* hint table, fallthrough */
248 case HB_TAG ('p', 'r', 'e', 'p'): /* hint table, fallthrough */
249 case HB_TAG ('h', 'd', 'm', 'x'): /* hint table, fallthrough */
250 case HB_TAG ('V', 'D', 'M', 'X'): /* hint table, fallthrough */
251 return plan->drop_hints;
252
253#ifdef HB_NO_SUBSET_LAYOUT
254 // Drop Layout Tables if requested.
255 case HB_OT_TAG_GDEF:
256 case HB_OT_TAG_GPOS:
257 case HB_OT_TAG_GSUB:
258 case HB_TAG ('m', 'o', 'r', 'x'):
259 case HB_TAG ('m', 'o', 'r', 't'):
260 case HB_TAG ('k', 'e', 'r', 'x'):
261 case HB_TAG ('k', 'e', 'r', 'n'):
262 return true;
263#endif
264
265 default:
266 return false;
267 }
268}
269
270/**
271 * hb_subset:
272 * @source: font face data to be subset.
273 * @input: input to use for the subsetting.
274 *
275 * Subsets a font according to provided input.
276 **/
277hb_face_t *
278hb_subset (hb_face_t *source,
279 hb_subset_input_t *input)
280{
281 if (unlikely (!input || !source)) return hb_face_get_empty ();
282
283 hb_subset_plan_t *plan = hb_subset_plan_create (source, input);
284
285 hb_tag_t table_tags[32];
286 unsigned int offset = 0, count;
287 bool success = true;
288 hb_set_t tags_set;
289 do {
290 count = ARRAY_LENGTH (table_tags);
291 hb_face_get_table_tags (source, offset, &count, table_tags);
292 for (unsigned int i = 0; i < count; i++)
293 {
294 hb_tag_t tag = table_tags[i];
295 if (_should_drop_table (plan, tag) && !tags_set.has (tag))
296 {
297 DEBUG_MSG(SUBSET, nullptr, "drop %c%c%c%c", HB_UNTAG (tag));
298 continue;
299 }
300 tags_set.add (tag);
301 success = success && _subset_table (plan, tag);
302 }
303 offset += count;
304 } while (success && count == ARRAY_LENGTH (table_tags));
305
306 hb_face_t *result = success ? hb_face_reference (plan->dest) : hb_face_get_empty ();
307 hb_subset_plan_destroy (plan);
308 return result;
309}
310