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-private.hh"
31 
32 namespace OT {
33 
34 
35 struct AxisValueMap
36 {
sanitizeOT::AxisValueMap37   inline bool sanitize (hb_sanitize_context_t *c) const
38   {
39     TRACE_SANITIZE (this);
40     return_trace (c->check_struct (this));
41   }
42 
43   public:
44   F2DOT14	fromCoord;	/* A normalized coordinate value obtained using
45 				 * default normalization. */
46   F2DOT14	toCoord;	/* The modified, normalized coordinate value. */
47 
48   public:
49   DEFINE_SIZE_STATIC (4);
50 };
51 
52 struct SegmentMaps : ArrayOf<AxisValueMap>
53 {
mapOT::SegmentMaps54   inline int map (int value) const
55   {
56     /* The following special-cases are not part of OpenType, which requires
57      * that at least -1, 0, and +1 must be mapped. But we include these as
58      * part of a better error recovery scheme. */
59 
60     if (!len)
61       return value;
62 
63     if (value <= array[0].fromCoord)
64       return value - array[0].fromCoord + array[0].toCoord;
65 
66     unsigned int i;
67     unsigned int count = len;
68     for (i = 1; i < count && value > array[i].fromCoord; i++)
69       ;
70 
71     if (value >= array[i].fromCoord)
72       return value - array[i].fromCoord + array[i].toCoord;
73 
74     if (unlikely (array[i-1].fromCoord == array[i].fromCoord))
75       return array[i-1].toCoord;
76 
77     int denom = array[i].fromCoord - array[i-1].fromCoord;
78     return array[i-1].toCoord +
79 	   (array[i].toCoord - array[i-1].toCoord) *
80 	   (value - array[i-1].fromCoord + denom/2) / denom;
81   }
82 
83   DEFINE_SIZE_ARRAY (2, array);
84 };
85 
86 /*
87  * avar — Axis Variations Table
88  */
89 
90 #define HB_OT_TAG_avar HB_TAG('a','v','a','r')
91 
92 struct avar
93 {
94   static const hb_tag_t tableTag	= HB_OT_TAG_avar;
95 
sanitizeOT::avar96   inline bool sanitize (hb_sanitize_context_t *c) const
97   {
98     TRACE_SANITIZE (this);
99     if (unlikely (!(version.sanitize (c) &&
100 		    version.major == 1 &&
101 		    c->check_struct (this))))
102       return_trace (false);
103 
104     const SegmentMaps *map = &axisSegmentMapsZ;
105     unsigned int count = axisCount;
106     for (unsigned int i = 0; i < count; i++)
107     {
108       if (unlikely (!map->sanitize (c)))
109         return_trace (false);
110       map = &StructAfter<SegmentMaps> (*map);
111     }
112 
113     return_trace (true);
114   }
115 
map_coordsOT::avar116   inline void map_coords (int *coords, unsigned int coords_length) const
117   {
118     unsigned int count = MIN<unsigned int> (coords_length, axisCount);
119 
120     const SegmentMaps *map = &axisSegmentMapsZ;
121     for (unsigned int i = 0; i < count; i++)
122     {
123       coords[i] = map->map (coords[i]);
124       map = &StructAfter<SegmentMaps> (*map);
125     }
126   }
127 
128   protected:
129   FixedVersion<>version;	/* Version of the avar table
130 				 * initially set to 0x00010000u */
131   USHORT	reserved;	/* This field is permanently reserved. Set to 0. */
132   USHORT	axisCount;	/* The number of variation axes in the font. This
133 				 * must be the same number as axisCount in the
134 				 * 'fvar' table. */
135   SegmentMaps	axisSegmentMapsZ;
136 
137   public:
138   DEFINE_SIZE_MIN (8);
139 };
140 
141 } /* namespace OT */
142 
143 
144 #endif /* HB_OT_VAR_AVAR_TABLE_HH */
145