1/*
2 * Copyright © 2022 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
25 */
26
27#include "graph.hh"
28#include "../hb-ot-layout-common.hh"
29
30#ifndef GRAPH_CLASSDEF_GRAPH_HH
31#define GRAPH_CLASSDEF_GRAPH_HH
32
33namespace graph {
34
35struct ClassDefFormat1 : public OT::ClassDefFormat1_3<SmallTypes>
36{
37 bool sanitize (graph_t::vertex_t& vertex) const
38 {
39 int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
40 constexpr unsigned min_size = OT::ClassDefFormat1_3<SmallTypes>::min_size;
41 if (vertex_len < min_size) return false;
42 return vertex_len >= min_size + classValue.get_size () - classValue.len.get_size ();
43 }
44};
45
46struct ClassDefFormat2 : public OT::ClassDefFormat2_4<SmallTypes>
47{
48 bool sanitize (graph_t::vertex_t& vertex) const
49 {
50 int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
51 constexpr unsigned min_size = OT::ClassDefFormat2_4<SmallTypes>::min_size;
52 if (vertex_len < min_size) return false;
53 return vertex_len >= min_size + rangeRecord.get_size () - rangeRecord.len.get_size ();
54 }
55};
56
57struct ClassDef : public OT::ClassDef
58{
59 template<typename It>
60 static bool add_class_def (gsubgpos_graph_context_t& c,
61 unsigned parent_id,
62 unsigned link_position,
63 It glyph_and_class,
64 unsigned max_size)
65 {
66 unsigned class_def_prime_id = c.graph.new_node (nullptr, nullptr);
67 auto& class_def_prime_vertex = c.graph.vertices_[class_def_prime_id];
68 if (!make_class_def (c, glyph_and_class, class_def_prime_id, max_size))
69 return false;
70
71 auto* class_def_link = c.graph.vertices_[parent_id].obj.real_links.push ();
72 class_def_link->width = SmallTypes::size;
73 class_def_link->objidx = class_def_prime_id;
74 class_def_link->position = link_position;
75 class_def_prime_vertex.add_parent (parent_id);
76
77 return true;
78 }
79
80 template<typename It>
81 static bool make_class_def (gsubgpos_graph_context_t& c,
82 It glyph_and_class,
83 unsigned dest_obj,
84 unsigned max_size)
85 {
86 char* buffer = (char*) hb_calloc (1, max_size);
87 hb_serialize_context_t serializer (buffer, max_size);
88 OT::ClassDef_serialize (&serializer, glyph_and_class);
89 serializer.end_serialize ();
90 if (serializer.in_error ())
91 {
92 hb_free (buffer);
93 return false;
94 }
95
96 hb_bytes_t class_def_copy = serializer.copy_bytes ();
97 if (!class_def_copy.arrayZ) return false;
98 // Give ownership to the context, it will cleanup the buffer.
99 if (!c.add_buffer ((char *) class_def_copy.arrayZ))
100 {
101 hb_free ((char *) class_def_copy.arrayZ);
102 return false;
103 }
104
105 auto& obj = c.graph.vertices_[dest_obj].obj;
106 obj.head = (char *) class_def_copy.arrayZ;
107 obj.tail = obj.head + class_def_copy.length;
108
109 hb_free (buffer);
110 return true;
111 }
112
113 bool sanitize (graph_t::vertex_t& vertex) const
114 {
115 int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
116 if (vertex_len < OT::ClassDef::min_size) return false;
117 switch (u.format)
118 {
119 case 1: return ((ClassDefFormat1*)this)->sanitize (vertex);
120 case 2: return ((ClassDefFormat2*)this)->sanitize (vertex);
121#ifndef HB_NO_BEYOND_64K
122 // Not currently supported
123 case 3:
124 case 4:
125#endif
126 default: return false;
127 }
128 }
129};
130
131
132struct class_def_size_estimator_t
133{
134 template<typename It>
135 class_def_size_estimator_t (It glyph_and_class)
136 : gids_consecutive (true), num_ranges_per_class (), glyphs_per_class ()
137 {
138 unsigned last_gid = (unsigned) -1;
139 for (auto p : + glyph_and_class)
140 {
141 unsigned gid = p.first;
142 unsigned klass = p.second;
143
144 if (last_gid != (unsigned) -1 && gid != last_gid + 1)
145 gids_consecutive = false;
146 last_gid = gid;
147
148 hb_set_t* glyphs;
149 if (glyphs_per_class.has (klass, &glyphs) && glyphs) {
150 glyphs->add (gid);
151 continue;
152 }
153
154 hb_set_t new_glyphs;
155 new_glyphs.add (gid);
156 glyphs_per_class.set (klass, std::move (new_glyphs));
157 }
158
159 if (in_error ()) return;
160
161 for (unsigned klass : glyphs_per_class.keys ())
162 {
163 if (!klass) continue; // class 0 doesn't get encoded.
164
165 const hb_set_t& glyphs = glyphs_per_class.get (klass);
166 hb_codepoint_t start = HB_SET_VALUE_INVALID;
167 hb_codepoint_t end = HB_SET_VALUE_INVALID;
168
169 unsigned count = 0;
170 while (glyphs.next_range (&start, &end))
171 count++;
172
173 num_ranges_per_class.set (klass, count);
174 }
175 }
176
177 // Incremental increase in the Coverage and ClassDef table size
178 // (worst case) if all glyphs associated with 'klass' were added.
179 unsigned incremental_coverage_size (unsigned klass) const
180 {
181 // Coverage takes 2 bytes per glyph worst case,
182 return 2 * glyphs_per_class.get (klass).get_population ();
183 }
184
185 // Incremental increase in the Coverage and ClassDef table size
186 // (worst case) if all glyphs associated with 'klass' were added.
187 unsigned incremental_class_def_size (unsigned klass) const
188 {
189 // ClassDef takes 6 bytes per range
190 unsigned class_def_2_size = 6 * num_ranges_per_class.get (klass);
191 if (gids_consecutive)
192 {
193 // ClassDef1 takes 2 bytes per glyph, but only can be used
194 // when gids are consecutive.
195 return hb_min (2 * glyphs_per_class.get (klass).get_population (), class_def_2_size);
196 }
197
198 return class_def_2_size;
199 }
200
201 bool in_error ()
202 {
203 if (num_ranges_per_class.in_error ()) return true;
204 if (glyphs_per_class.in_error ()) return true;
205
206 for (const hb_set_t& s : glyphs_per_class.values ())
207 {
208 if (s.in_error ()) return true;
209 }
210 return false;
211 }
212
213 private:
214 bool gids_consecutive;
215 hb_hashmap_t<unsigned, unsigned> num_ranges_per_class;
216 hb_hashmap_t<unsigned, hb_set_t> glyphs_per_class;
217};
218
219
220}
221
222#endif // GRAPH_CLASSDEF_GRAPH_HH
223