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