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_VAR_AVAR_TABLE_HH
28#define HB_OT_VAR_AVAR_TABLE_HH
29
30#include "hb-open-type.hh"
31
32/*
33 * avar -- Axis Variations
34 * https://docs.microsoft.com/en-us/typography/opentype/spec/avar
35 */
36
37#define HB_OT_TAG_avar HB_TAG('a','v','a','r')
38
39
40namespace OT {
41
42
43struct AxisValueMap
44{
45 bool sanitize (hb_sanitize_context_t *c) const
46 {
47 TRACE_SANITIZE (this);
48 return_trace (c->check_struct (this));
49 }
50
51 public:
52 F2DOT14 coords[2];
53// F2DOT14 fromCoord; /* A normalized coordinate value obtained using
54// * default normalization. */
55// F2DOT14 toCoord; /* The modified, normalized coordinate value. */
56
57 public:
58 DEFINE_SIZE_STATIC (4);
59};
60
61struct SegmentMaps : ArrayOf<AxisValueMap>
62{
63 int map (int value, unsigned int from_offset = 0, unsigned int to_offset = 1) const
64 {
65#define fromCoord coords[from_offset]
66#define toCoord coords[to_offset]
67 /* The following special-cases are not part of OpenType, which requires
68 * that at least -1, 0, and +1 must be mapped. But we include these as
69 * part of a better error recovery scheme. */
70 if (len < 2)
71 {
72 if (!len)
73 return value;
74 else /* len == 1*/
75 return value - arrayZ[0].fromCoord + arrayZ[0].toCoord;
76 }
77
78 if (value <= arrayZ[0].fromCoord)
79 return value - arrayZ[0].fromCoord + arrayZ[0].toCoord;
80
81 unsigned int i;
82 unsigned int count = len;
83 for (i = 1; i < count && value > arrayZ[i].fromCoord; i++)
84 ;
85
86 if (value >= arrayZ[i].fromCoord)
87 return value - arrayZ[i].fromCoord + arrayZ[i].toCoord;
88
89 if (unlikely (arrayZ[i-1].fromCoord == arrayZ[i].fromCoord))
90 return arrayZ[i-1].toCoord;
91
92 int denom = arrayZ[i].fromCoord - arrayZ[i-1].fromCoord;
93 return arrayZ[i-1].toCoord +
94 ((arrayZ[i].toCoord - arrayZ[i-1].toCoord) *
95 (value - arrayZ[i-1].fromCoord) + denom/2) / denom;
96#undef toCoord
97#undef fromCoord
98 }
99
100 int unmap (int value) const { return map (value, 1, 0); }
101
102 public:
103 DEFINE_SIZE_ARRAY (2, *this);
104};
105
106struct avar
107{
108 static constexpr hb_tag_t tableTag = HB_OT_TAG_avar;
109
110 bool sanitize (hb_sanitize_context_t *c) const
111 {
112 TRACE_SANITIZE (this);
113 if (unlikely (!(version.sanitize (c) &&
114 version.major == 1 &&
115 c->check_struct (this))))
116 return_trace (false);
117
118 const SegmentMaps *map = &firstAxisSegmentMaps;
119 unsigned int count = axisCount;
120 for (unsigned int i = 0; i < count; i++)
121 {
122 if (unlikely (!map->sanitize (c)))
123 return_trace (false);
124 map = &StructAfter<SegmentMaps> (*map);
125 }
126
127 return_trace (true);
128 }
129
130 void map_coords (int *coords, unsigned int coords_length) const
131 {
132 unsigned int count = hb_min (coords_length, axisCount);
133
134 const SegmentMaps *map = &firstAxisSegmentMaps;
135 for (unsigned int i = 0; i < count; i++)
136 {
137 coords[i] = map->map (coords[i]);
138 map = &StructAfter<SegmentMaps> (*map);
139 }
140 }
141
142 void unmap_coords (int *coords, unsigned int coords_length) const
143 {
144 unsigned int count = hb_min (coords_length, axisCount);
145
146 const SegmentMaps *map = &firstAxisSegmentMaps;
147 for (unsigned int i = 0; i < count; i++)
148 {
149 coords[i] = map->unmap (coords[i]);
150 map = &StructAfter<SegmentMaps> (*map);
151 }
152 }
153
154 protected:
155 FixedVersion<>version; /* Version of the avar table
156 * initially set to 0x00010000u */
157 HBUINT16 reserved; /* This field is permanently reserved. Set to 0. */
158 HBUINT16 axisCount; /* The number of variation axes in the font. This
159 * must be the same number as axisCount in the
160 * 'fvar' table. */
161 SegmentMaps firstAxisSegmentMaps;
162
163 public:
164 DEFINE_SIZE_MIN (8);
165};
166
167} /* namespace OT */
168
169
170#endif /* HB_OT_VAR_AVAR_TABLE_HH */
171