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 < 2)
61     {
62       if (!len)
63 	return value;
64       else /* len == 1*/
65 	return value - array[0].fromCoord + array[0].toCoord;
66     }
67 
68     if (value <= array[0].fromCoord)
69       return value - array[0].fromCoord + array[0].toCoord;
70 
71     unsigned int i;
72     unsigned int count = len;
73     for (i = 1; i < count && value > array[i].fromCoord; i++)
74       ;
75 
76     if (value >= array[i].fromCoord)
77       return value - array[i].fromCoord + array[i].toCoord;
78 
79     if (unlikely (array[i-1].fromCoord == array[i].fromCoord))
80       return array[i-1].toCoord;
81 
82     int denom = array[i].fromCoord - array[i-1].fromCoord;
83     return array[i-1].toCoord +
84 	   ((array[i].toCoord - array[i-1].toCoord) *
85 	    (value - array[i-1].fromCoord) + denom/2) / denom;
86   }
87 
88   DEFINE_SIZE_ARRAY (2, array);
89 };
90 
91 /*
92  * avar — Axis Variations Table
93  */
94 
95 #define HB_OT_TAG_avar HB_TAG('a','v','a','r')
96 
97 struct avar
98 {
99   static const hb_tag_t tableTag	= HB_OT_TAG_avar;
100 
sanitizeOT::avar101   inline bool sanitize (hb_sanitize_context_t *c) const
102   {
103     TRACE_SANITIZE (this);
104     if (unlikely (!(version.sanitize (c) &&
105 		    version.major == 1 &&
106 		    c->check_struct (this))))
107       return_trace (false);
108 
109     const SegmentMaps *map = &axisSegmentMapsZ;
110     unsigned int count = axisCount;
111     for (unsigned int i = 0; i < count; i++)
112     {
113       if (unlikely (!map->sanitize (c)))
114         return_trace (false);
115       map = &StructAfter<SegmentMaps> (*map);
116     }
117 
118     return_trace (true);
119   }
120 
map_coordsOT::avar121   inline void map_coords (int *coords, unsigned int coords_length) const
122   {
123     unsigned int count = MIN<unsigned int> (coords_length, axisCount);
124 
125     const SegmentMaps *map = &axisSegmentMapsZ;
126     for (unsigned int i = 0; i < count; i++)
127     {
128       coords[i] = map->map (coords[i]);
129       map = &StructAfter<SegmentMaps> (*map);
130     }
131   }
132 
133   protected:
134   FixedVersion<>version;	/* Version of the avar table
135 				 * initially set to 0x00010000u */
136   UINT16	reserved;	/* This field is permanently reserved. Set to 0. */
137   UINT16	axisCount;	/* The number of variation axes in the font. This
138 				 * must be the same number as axisCount in the
139 				 * 'fvar' table. */
140   SegmentMaps	axisSegmentMapsZ;
141 
142   public:
143   DEFINE_SIZE_MIN (8);
144 };
145 
146 } /* namespace OT */
147 
148 
149 #endif /* HB_OT_VAR_AVAR_TABLE_HH */
150