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, Roderick Sheeter
25 */
26
27 #include "hb-open-type.hh"
28 #include "hb-ot-glyf-table.hh"
29 #include "hb-set.h"
30 #include "hb-subset-glyf.hh"
31
32 static bool
33 _calculate_glyf_and_loca_prime_size (const OT::glyf::accelerator_t &glyf,
34 hb_vector_t<hb_codepoint_t> &glyph_ids,
35 hb_bool_t drop_hints,
36 bool *use_short_loca /* OUT */,
37 unsigned int *glyf_size /* OUT */,
38 unsigned int *loca_size /* OUT */,
39 hb_vector_t<unsigned int> *instruction_ranges /* OUT */)
40 {
41 unsigned int total = 0;
42 for (unsigned int i = 0; i < glyph_ids.length; i++)
43 {
44 hb_codepoint_t next_glyph = glyph_ids[i];
45 if (!instruction_ranges->resize (instruction_ranges->length + 2))
46 {
47 DEBUG_MSG(SUBSET, nullptr, "Failed to resize instruction_ranges.");
48 return false;
49 }
50 unsigned int *instruction_start = &(*instruction_ranges)[instruction_ranges->length - 2];
51 *instruction_start = 0;
52 unsigned int *instruction_end = &(*instruction_ranges)[instruction_ranges->length - 1];
53 *instruction_end = 0;
54
55 unsigned int start_offset, end_offset;
56 if (unlikely (!(glyf.get_offsets (next_glyph, &start_offset, &end_offset) &&
57 glyf.remove_padding (start_offset, &end_offset))))
58 {
59 DEBUG_MSG(SUBSET, nullptr, "Invalid gid %d", next_glyph);
60 continue;
61 }
62 if (end_offset - start_offset < OT::glyf::GlyphHeader::static_size)
63 continue; /* 0-length glyph */
64
65 if (drop_hints)
66 {
67 if (unlikely (!glyf.get_instruction_offsets (start_offset, end_offset,
68 instruction_start, instruction_end)))
69 {
70 DEBUG_MSG(SUBSET, nullptr, "Unable to get instruction offsets for %d", next_glyph);
71 return false;
72 }
73 }
74
75 total += end_offset - start_offset - (*instruction_end - *instruction_start);
76 /* round2 so short loca will work */
77 total += total % 2;
78 }
79
80 *glyf_size = total;
81 *use_short_loca = (total <= 131070);
82 *loca_size = (glyph_ids.length + 1)
83 * (*use_short_loca ? sizeof (OT::HBUINT16) : sizeof (OT::HBUINT32));
84
85 DEBUG_MSG(SUBSET, nullptr, "preparing to subset glyf: final size %d, loca size %d, using %s loca",
86 total,
87 *loca_size,
88 *use_short_loca ? "short" : "long");
89 return true;
90 }
91
92 static bool
93 _write_loca_entry (unsigned int id,
94 unsigned int offset,
95 bool is_short,
96 void *loca_prime,
97 unsigned int loca_size)
98 {
99 unsigned int entry_size = is_short ? sizeof (OT::HBUINT16) : sizeof (OT::HBUINT32);
100 if ((id + 1) * entry_size <= loca_size)
101 {
102 if (is_short) {
103 ((OT::HBUINT16*) loca_prime) [id].set (offset / 2);
104 } else {
105 ((OT::HBUINT32*) loca_prime) [id].set (offset);
106 }
107 return true;
108 }
109
110 // Offset was not written because the write is out of bounds.
111 DEBUG_MSG(SUBSET,
112 nullptr,
113 "WARNING: Attempted to write an out of bounds loca entry at index %d. Loca size is %d.",
114 id,
115 loca_size);
116 return false;
117 }
118
119 static void
120 _update_components (hb_subset_plan_t * plan,
121 char * glyph_start,
122 unsigned int length)
123 {
124 OT::glyf::CompositeGlyphHeader::Iterator iterator;
125 if (OT::glyf::CompositeGlyphHeader::get_iterator (glyph_start,
126 length,
127 &iterator))
128 {
129 do
130 {
131 hb_codepoint_t new_gid;
132 if (!plan->new_gid_for_old_gid (iterator.current->glyphIndex,
133 &new_gid))
134 continue;
135
136 ((OT::glyf::CompositeGlyphHeader *) iterator.current)->glyphIndex.set (new_gid);
137 } while (iterator.move_to_next ());
138 }
139 }
140
141 static bool _remove_composite_instruction_flag (char *glyf_prime, unsigned int length)
142 {
143 /* remove WE_HAVE_INSTRUCTIONS from flags in dest */
144 OT::glyf::CompositeGlyphHeader::Iterator composite_it;
145 if (unlikely (!OT::glyf::CompositeGlyphHeader::get_iterator (glyf_prime, length, &composite_it))) return false;
146 const OT::glyf::CompositeGlyphHeader *glyph;
147 do {
148 glyph = composite_it.current;
149 OT::HBUINT16 *flags = const_cast<OT::HBUINT16 *> (&glyph->flags);
150 flags->set ( (uint16_t) *flags & ~OT::glyf::CompositeGlyphHeader::WE_HAVE_INSTRUCTIONS);
151 } while (composite_it.move_to_next ());
152 return true;
153 }
154
155 static bool
156 _write_glyf_and_loca_prime (hb_subset_plan_t *plan,
157 const OT::glyf::accelerator_t &glyf,
158 const char *glyf_data,
159 bool use_short_loca,
160 hb_vector_t<unsigned int> &instruction_ranges,
161 unsigned int glyf_prime_size,
162 char *glyf_prime_data /* OUT */,
163 unsigned int loca_prime_size,
164 char *loca_prime_data /* OUT */)
165 {
166 hb_vector_t<hb_codepoint_t> &glyph_ids = plan->glyphs;
167 char *glyf_prime_data_next = glyf_prime_data;
168
169 bool success = true;
170 for (unsigned int i = 0; i < glyph_ids.length; i++)
171 {
172 unsigned int start_offset, end_offset;
173 if (unlikely (!(glyf.get_offsets (glyph_ids[i], &start_offset, &end_offset) &&
174 glyf.remove_padding (start_offset, &end_offset))))
175 end_offset = start_offset = 0;
176
177 unsigned int instruction_start = instruction_ranges[i * 2];
178 unsigned int instruction_end = instruction_ranges[i * 2 + 1];
179
180 int length = end_offset - start_offset - (instruction_end - instruction_start);
181
182 if (glyf_prime_data_next + length > glyf_prime_data + glyf_prime_size)
183 {
184 DEBUG_MSG(SUBSET,
185 nullptr,
186 "WARNING: Attempted to write an out of bounds glyph entry for gid %d (length %d)",
187 i, length);
188 return false;
189 }
190
191 if (instruction_start == instruction_end)
192 memcpy (glyf_prime_data_next, glyf_data + start_offset, length);
193 else
194 {
195 memcpy (glyf_prime_data_next, glyf_data + start_offset, instruction_start - start_offset);
196 memcpy (glyf_prime_data_next + instruction_start - start_offset, glyf_data + instruction_end, end_offset - instruction_end);
197 /* if the instructions end at the end this was a composite glyph, else simple */
198 if (instruction_end == end_offset)
199 {
200 if (unlikely (!_remove_composite_instruction_flag (glyf_prime_data_next, length))) return false;
201 }
202 else
203 /* zero instruction length, which is just before instruction_start */
204 memset (glyf_prime_data_next + instruction_start - start_offset - 2, 0, 2);
205 }
206
207 success = success && _write_loca_entry (i,
208 glyf_prime_data_next - glyf_prime_data,
209 use_short_loca,
210 loca_prime_data,
211 loca_prime_size);
212 _update_components (plan, glyf_prime_data_next, length);
213
214 // TODO: don't align to two bytes if using long loca.
215 glyf_prime_data_next += length + (length % 2); // Align to 2 bytes for short loca.
216 }
217
218 success = success && _write_loca_entry (glyph_ids.length,
219 glyf_prime_data_next - glyf_prime_data,
220 use_short_loca,
221 loca_prime_data,
222 loca_prime_size);
223 return success;
224 }
225
226 static bool
227 _hb_subset_glyf_and_loca (const OT::glyf::accelerator_t &glyf,
228 const char *glyf_data,
229 hb_subset_plan_t *plan,
230 bool *use_short_loca,
231 hb_blob_t **glyf_prime /* OUT */,
232 hb_blob_t **loca_prime /* OUT */)
233 {
234 // TODO(grieger): Sanity check allocation size for the new table.
235 hb_vector_t<hb_codepoint_t> &glyphs_to_retain = plan->glyphs;
236
237 unsigned int glyf_prime_size;
238 unsigned int loca_prime_size;
239 hb_vector_t<unsigned int> instruction_ranges;
240 instruction_ranges.init ();
241
242 if (unlikely (!_calculate_glyf_and_loca_prime_size (glyf,
243 glyphs_to_retain,
244 plan->drop_hints,
245 use_short_loca,
246 &glyf_prime_size,
247 &loca_prime_size,
248 &instruction_ranges))) {
249 instruction_ranges.fini ();
250 return false;
251 }
252
253 char *glyf_prime_data = (char *) calloc (1, glyf_prime_size);
254 char *loca_prime_data = (char *) calloc (1, loca_prime_size);
255 if (unlikely (!_write_glyf_and_loca_prime (plan, glyf, glyf_data,
256 *use_short_loca,
257 instruction_ranges,
258 glyf_prime_size, glyf_prime_data,
259 loca_prime_size, loca_prime_data))) {
260 free (glyf_prime_data);
261 free (loca_prime_data);
262 instruction_ranges.fini ();
263 return false;
264 }
265 instruction_ranges.fini ();
266
267 *glyf_prime = hb_blob_create (glyf_prime_data,
268 glyf_prime_size,
269 HB_MEMORY_MODE_READONLY,
270 glyf_prime_data,
271 free);
272 *loca_prime = hb_blob_create (loca_prime_data,
273 loca_prime_size,
274 HB_MEMORY_MODE_READONLY,
275 loca_prime_data,
276 free);
277 return true;
278 }
279
280 /**
281 * hb_subset_glyf:
282 * Subsets the glyph table according to a provided plan.
283 *
284 * Return value: subsetted glyf table.
285 *
286 * Since: 1.7.5
287 **/
288 bool
289 hb_subset_glyf_and_loca (hb_subset_plan_t *plan,
290 bool *use_short_loca, /* OUT */
291 hb_blob_t **glyf_prime, /* OUT */
292 hb_blob_t **loca_prime /* OUT */)
293 {
294 hb_blob_t *glyf_blob = hb_sanitize_context_t ().reference_table<OT::glyf> (plan->source);
295 const char *glyf_data = hb_blob_get_data (glyf_blob, nullptr);
296
297 OT::glyf::accelerator_t glyf;
298 glyf.init (plan->source);
299 bool result = _hb_subset_glyf_and_loca (glyf,
300 glyf_data,
301 plan,
302 use_short_loca,
303 glyf_prime,
304 loca_prime);
305
306 hb_blob_destroy (glyf_blob);
307 glyf.fini ();
308
309 return result;
310 }