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 fromCoord; /* A normalized coordinate value obtained using
53 * default normalization. */
54 F2DOT14 toCoord; /* The modified, normalized coordinate value. */
55
56 public:
57 DEFINE_SIZE_STATIC (4);
58};
59
60struct SegmentMaps : ArrayOf<AxisValueMap>
61{
62 int map (int value) const
63 {
64 /* The following special-cases are not part of OpenType, which requires
65 * that at least -1, 0, and +1 must be mapped. But we include these as
66 * part of a better error recovery scheme. */
67
68 if (len < 2)
69 {
70 if (!len)
71 return value;
72 else /* len == 1*/
73 return value - arrayZ[0].fromCoord + arrayZ[0].toCoord;
74 }
75
76 if (value <= arrayZ[0].fromCoord)
77 return value - arrayZ[0].fromCoord + arrayZ[0].toCoord;
78
79 unsigned int i;
80 unsigned int count = len;
81 for (i = 1; i < count && value > arrayZ[i].fromCoord; i++)
82 ;
83
84 if (value >= arrayZ[i].fromCoord)
85 return value - arrayZ[i].fromCoord + arrayZ[i].toCoord;
86
87 if (unlikely (arrayZ[i-1].fromCoord == arrayZ[i].fromCoord))
88 return arrayZ[i-1].toCoord;
89
90 int denom = arrayZ[i].fromCoord - arrayZ[i-1].fromCoord;
91 return arrayZ[i-1].toCoord +
92 ((arrayZ[i].toCoord - arrayZ[i-1].toCoord) *
93 (value - arrayZ[i-1].fromCoord) + denom/2) / denom;
94 }
95
96 public:
97 DEFINE_SIZE_ARRAY (2, *this);
98};
99
100struct avar
101{
102 static constexpr hb_tag_t tableTag = HB_OT_TAG_avar;
103
104 bool sanitize (hb_sanitize_context_t *c) const
105 {
106 TRACE_SANITIZE (this);
107 if (unlikely (!(version.sanitize (c) &&
108 version.major == 1 &&
109 c->check_struct (this))))
110 return_trace (false);
111
112 const SegmentMaps *map = &firstAxisSegmentMaps;
113 unsigned int count = axisCount;
114 for (unsigned int i = 0; i < count; i++)
115 {
116 if (unlikely (!map->sanitize (c)))
117 return_trace (false);
118 map = &StructAfter<SegmentMaps> (*map);
119 }
120
121 return_trace (true);
122 }
123
124 void map_coords (int *coords, unsigned int coords_length) const
125 {
126 unsigned int count = MIN<unsigned int> (coords_length, axisCount);
127
128 const SegmentMaps *map = &firstAxisSegmentMaps;
129 for (unsigned int i = 0; i < count; i++)
130 {
131 coords[i] = map->map (coords[i]);
132 map = &StructAfter<SegmentMaps> (*map);
133 }
134 }
135
136 protected:
137 FixedVersion<>version; /* Version of the avar table
138 * initially set to 0x00010000u */
139 HBUINT16 reserved; /* This field is permanently reserved. Set to 0. */
140 HBUINT16 axisCount; /* The number of variation axes in the font. This
141 * must be the same number as axisCount in the
142 * 'fvar' table. */
143 SegmentMaps firstAxisSegmentMaps;
144
145 public:
146 DEFINE_SIZE_MIN (8);
147};
148
149} /* namespace OT */
150
151
152#endif /* HB_OT_VAR_AVAR_TABLE_HH */
153