1/*
2 * Copyright © 2017 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
25 */
26
27#ifndef HB_OT_KERN_TABLE_HH
28#define HB_OT_KERN_TABLE_HH
29
30#include "hb-aat-layout-kerx-table.hh"
31
32
33/*
34 * kern -- Kerning
35 * https://docs.microsoft.com/en-us/typography/opentype/spec/kern
36 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6kern.html
37 */
38#define HB_OT_TAG_kern HB_TAG('k','e','r','n')
39
40
41namespace OT {
42
43
44template <typename KernSubTableHeader>
45struct KernSubTableFormat3
46{
47 int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
48 {
49 hb_array_t<const FWORD> kernValue = kernValueZ.as_array (kernValueCount);
50 hb_array_t<const HBUINT8> leftClass = StructAfter<const UnsizedArrayOf<HBUINT8>> (kernValue).as_array (glyphCount);
51 hb_array_t<const HBUINT8> rightClass = StructAfter<const UnsizedArrayOf<HBUINT8>> (leftClass).as_array (glyphCount);
52 hb_array_t<const HBUINT8> kernIndex = StructAfter<const UnsizedArrayOf<HBUINT8>> (rightClass).as_array (leftClassCount * rightClassCount);
53
54 unsigned int leftC = leftClass[left];
55 unsigned int rightC = rightClass[right];
56 if (unlikely (leftC >= leftClassCount || rightC >= rightClassCount))
57 return 0;
58 unsigned int i = leftC * rightClassCount + rightC;
59 return kernValue[kernIndex[i]];
60 }
61
62 bool apply (AAT::hb_aat_apply_context_t *c) const
63 {
64 TRACE_APPLY (this);
65
66 if (!c->plan->requested_kerning)
67 return false;
68
69 if (header.coverage & header.Backwards)
70 return false;
71
72 hb_kern_machine_t<KernSubTableFormat3> machine (*this, header.coverage & header.CrossStream);
73 machine.kern (c->font, c->buffer, c->plan->kern_mask);
74
75 return_trace (true);
76 }
77
78 bool sanitize (hb_sanitize_context_t *c) const
79 {
80 TRACE_SANITIZE (this);
81 return_trace (c->check_struct (this) &&
82 c->check_range (kernValueZ,
83 kernValueCount * sizeof (FWORD) +
84 glyphCount * 2 +
85 leftClassCount * rightClassCount));
86 }
87
88 protected:
89 KernSubTableHeader header;
90 HBUINT16 glyphCount; /* The number of glyphs in this font. */
91 HBUINT8 kernValueCount; /* The number of kerning values. */
92 HBUINT8 leftClassCount; /* The number of left-hand classes. */
93 HBUINT8 rightClassCount;/* The number of right-hand classes. */
94 HBUINT8 flags; /* Set to zero (reserved for future use). */
95 UnsizedArrayOf<FWORD> kernValueZ; /* The kerning values.
96 * Length kernValueCount. */
97#if 0
98 UnsizedArrayOf<HBUINT8>leftClass; /* The left-hand classes.
99 * Length glyphCount. */
100 UnsizedArrayOf<HBUINT8>rightClass; /* The right-hand classes.
101 * Length glyphCount. */
102 UnsizedArrayOf<HBUINT8>kernIndex; /* The indices into the kernValue array.
103 * Length leftClassCount * rightClassCount */
104#endif
105 public:
106 DEFINE_SIZE_ARRAY (KernSubTableHeader::static_size + 6, kernValueZ);
107};
108
109template <typename KernSubTableHeader>
110struct KernSubTable
111{
112 unsigned int get_size () const { return u.header.length; }
113 unsigned int get_type () const { return u.header.format; }
114
115 int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
116 {
117 switch (get_type ()) {
118 /* This method hooks up to hb_font_t's get_h_kerning. Only support Format0. */
119 case 0: return u.format0.get_kerning (left, right);
120 default:return 0;
121 }
122 }
123
124 template <typename context_t, typename ...Ts>
125 typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
126 {
127 unsigned int subtable_type = get_type ();
128 TRACE_DISPATCH (this, subtable_type);
129 switch (subtable_type) {
130 case 0: return_trace (c->dispatch (u.format0));
131#ifndef HB_NO_AAT_SHAPE
132 case 1: return_trace (u.header.apple ? c->dispatch (u.format1, hb_forward<Ts> (ds)...) : c->default_return_value ());
133#endif
134 case 2: return_trace (c->dispatch (u.format2));
135#ifndef HB_NO_AAT_SHAPE
136 case 3: return_trace (u.header.apple ? c->dispatch (u.format3, hb_forward<Ts> (ds)...) : c->default_return_value ());
137#endif
138 default: return_trace (c->default_return_value ());
139 }
140 }
141
142 bool sanitize (hb_sanitize_context_t *c) const
143 {
144 TRACE_SANITIZE (this);
145 if (unlikely (!u.header.sanitize (c) ||
146 u.header.length < u.header.min_size ||
147 !c->check_range (this, u.header.length))) return_trace (false);
148
149 return_trace (dispatch (c));
150 }
151
152 public:
153 union {
154 KernSubTableHeader header;
155 AAT::KerxSubTableFormat0<KernSubTableHeader> format0;
156 AAT::KerxSubTableFormat1<KernSubTableHeader> format1;
157 AAT::KerxSubTableFormat2<KernSubTableHeader> format2;
158 KernSubTableFormat3<KernSubTableHeader> format3;
159 } u;
160 public:
161 DEFINE_SIZE_MIN (KernSubTableHeader::static_size);
162};
163
164
165struct KernOTSubTableHeader
166{
167 static constexpr bool apple = false;
168 typedef AAT::ObsoleteTypes Types;
169
170 unsigned tuple_count () const { return 0; }
171 bool is_horizontal () const { return (coverage & Horizontal); }
172
173 enum Coverage
174 {
175 Horizontal = 0x01u,
176 Minimum = 0x02u,
177 CrossStream = 0x04u,
178 Override = 0x08u,
179
180 /* Not supported: */
181 Backwards = 0x00u,
182 Variation = 0x00u,
183 };
184
185 bool sanitize (hb_sanitize_context_t *c) const
186 {
187 TRACE_SANITIZE (this);
188 return_trace (c->check_struct (this));
189 }
190
191 public:
192 HBUINT16 versionZ; /* Unused. */
193 HBUINT16 length; /* Length of the subtable (including this header). */
194 HBUINT8 format; /* Subtable format. */
195 HBUINT8 coverage; /* Coverage bits. */
196 public:
197 DEFINE_SIZE_STATIC (6);
198};
199
200struct KernOT : AAT::KerxTable<KernOT>
201{
202 friend struct AAT::KerxTable<KernOT>;
203
204 static constexpr hb_tag_t tableTag = HB_OT_TAG_kern;
205 static constexpr unsigned minVersion = 0u;
206
207 typedef KernOTSubTableHeader SubTableHeader;
208 typedef SubTableHeader::Types Types;
209 typedef KernSubTable<SubTableHeader> SubTable;
210
211 protected:
212 HBUINT16 version; /* Version--0x0000u */
213 HBUINT16 tableCount; /* Number of subtables in the kerning table. */
214 SubTable firstSubTable; /* Subtables. */
215 public:
216 DEFINE_SIZE_MIN (4);
217};
218
219
220struct KernAATSubTableHeader
221{
222 static constexpr bool apple = true;
223 typedef AAT::ObsoleteTypes Types;
224
225 unsigned tuple_count () const { return 0; }
226 bool is_horizontal () const { return !(coverage & Vertical); }
227
228 enum Coverage
229 {
230 Vertical = 0x80u,
231 CrossStream = 0x40u,
232 Variation = 0x20u,
233
234 /* Not supported: */
235 Backwards = 0x00u,
236 };
237
238 bool sanitize (hb_sanitize_context_t *c) const
239 {
240 TRACE_SANITIZE (this);
241 return_trace (c->check_struct (this));
242 }
243
244 public:
245 HBUINT32 length; /* Length of the subtable (including this header). */
246 HBUINT8 coverage; /* Coverage bits. */
247 HBUINT8 format; /* Subtable format. */
248 HBUINT16 tupleIndex; /* The tuple index (used for variations fonts).
249 * This value specifies which tuple this subtable covers.
250 * Note: We don't implement. */
251 public:
252 DEFINE_SIZE_STATIC (8);
253};
254
255struct KernAAT : AAT::KerxTable<KernAAT>
256{
257 friend struct AAT::KerxTable<KernAAT>;
258
259 static constexpr hb_tag_t tableTag = HB_OT_TAG_kern;
260 static constexpr unsigned minVersion = 0x00010000u;
261
262 typedef KernAATSubTableHeader SubTableHeader;
263 typedef SubTableHeader::Types Types;
264 typedef KernSubTable<SubTableHeader> SubTable;
265
266 protected:
267 HBUINT32 version; /* Version--0x00010000u */
268 HBUINT32 tableCount; /* Number of subtables in the kerning table. */
269 SubTable firstSubTable; /* Subtables. */
270 public:
271 DEFINE_SIZE_MIN (8);
272};
273
274struct kern
275{
276 static constexpr hb_tag_t tableTag = HB_OT_TAG_kern;
277
278 bool has_data () const { return u.version32; }
279 unsigned get_type () const { return u.major; }
280
281 bool has_state_machine () const
282 {
283 switch (get_type ()) {
284 case 0: return u.ot.has_state_machine ();
285#ifndef HB_NO_AAT_SHAPE
286 case 1: return u.aat.has_state_machine ();
287#endif
288 default:return false;
289 }
290 }
291
292 bool has_cross_stream () const
293 {
294 switch (get_type ()) {
295 case 0: return u.ot.has_cross_stream ();
296#ifndef HB_NO_AAT_SHAPE
297 case 1: return u.aat.has_cross_stream ();
298#endif
299 default:return false;
300 }
301 }
302
303 int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
304 {
305 switch (get_type ()) {
306 case 0: return u.ot.get_h_kerning (left, right);
307#ifndef HB_NO_AAT_SHAPE
308 case 1: return u.aat.get_h_kerning (left, right);
309#endif
310 default:return 0;
311 }
312 }
313
314 bool apply (AAT::hb_aat_apply_context_t *c) const
315 { return dispatch (c); }
316
317 template <typename context_t, typename ...Ts>
318 typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
319 {
320 unsigned int subtable_type = get_type ();
321 TRACE_DISPATCH (this, subtable_type);
322 switch (subtable_type) {
323 case 0: return_trace (c->dispatch (u.ot, hb_forward<Ts> (ds)...));
324#ifndef HB_NO_AAT_SHAPE
325 case 1: return_trace (c->dispatch (u.aat, hb_forward<Ts> (ds)...));
326#endif
327 default: return_trace (c->default_return_value ());
328 }
329 }
330
331 bool sanitize (hb_sanitize_context_t *c) const
332 {
333 TRACE_SANITIZE (this);
334 if (!u.version32.sanitize (c)) return_trace (false);
335 return_trace (dispatch (c));
336 }
337
338 protected:
339 union {
340 HBUINT32 version32;
341 HBUINT16 major;
342 KernOT ot;
343#ifndef HB_NO_AAT_SHAPE
344 KernAAT aat;
345#endif
346 } u;
347 public:
348 DEFINE_SIZE_UNION (4, version32);
349};
350
351} /* namespace OT */
352
353
354#endif /* HB_OT_KERN_TABLE_HH */
355