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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_MVAR_TABLE_HH
28 #define HB_OT_VAR_MVAR_TABLE_HH
29 
30 #include "hb-ot-layout-common-private.hh"
31 
32 
33 namespace OT {
34 
35 
36 struct VariationValueRecord
37 {
sanitizeOT::VariationValueRecord38   inline bool sanitize (hb_sanitize_context_t *c) const
39   {
40     TRACE_SANITIZE (this);
41     return_trace (c->check_struct (this));
42   }
43 
44   public:
45   Tag		valueTag;	/* Four-byte tag identifying a font-wide measure. */
46   UINT32		varIdx;		/* Outer/inner index into VariationStore item. */
47 
48   public:
49   DEFINE_SIZE_STATIC (8);
50 };
51 
52 
53 /*
54  * MVAR -- Metrics Variations Table
55  */
56 
57 #define HB_OT_TAG_MVAR HB_TAG('M','V','A','R')
58 
59 struct MVAR
60 {
61   static const hb_tag_t tableTag	= HB_OT_TAG_MVAR;
62 
sanitizeOT::MVAR63   inline bool sanitize (hb_sanitize_context_t *c) const
64   {
65     TRACE_SANITIZE (this);
66     return_trace (version.sanitize (c) &&
67 		  likely (version.major == 1) &&
68 		  c->check_struct (this) &&
69 		  valueRecordSize >= VariationValueRecord::static_size &&
70 		  varStore.sanitize (c, this) &&
71 		  c->check_array (values, valueRecordSize, valueRecordCount));
72   }
73 
get_varOT::MVAR74   inline float get_var (hb_tag_t tag,
75 			int *coords, unsigned int coord_count) const
76   {
77     const VariationValueRecord *record;
78     record = (VariationValueRecord *) bsearch (&tag, values,
79 					       valueRecordCount, valueRecordSize,
80 					       tag_compare);
81     if (!record)
82       return 0.;
83 
84     return (this+varStore).get_delta (record->varIdx, coords, coord_count);
85   }
86 
87 protected:
tag_compareOT::MVAR88   static inline int tag_compare (const void *pa, const void *pb)
89   {
90     const hb_tag_t *a = (const hb_tag_t *) pa;
91     const Tag *b = (const Tag *) pb;
92     return b->cmp (*a);
93   }
94 
95   protected:
96   FixedVersion<>version;	/* Version of the metrics variation table
97 				 * initially set to 0x00010000u */
98   UINT16	reserved;	/* Not used; set to 0. */
99   UINT16	valueRecordSize;/* The size in bytes of each value record —
100 				 * must be greater than zero. */
101   UINT16	valueRecordCount;/* The number of value records — may be zero. */
102   OffsetTo<VariationStore>
103 		varStore;	/* Offset to item variation store table. */
104   UINT8		values[VAR];	/* Array of value records. The records must be
105 				 * in binary order of their valueTag field. */
106 
107   public:
108   DEFINE_SIZE_ARRAY (12, values);
109 };
110 
111 } /* namespace OT */
112 
113 
114 #endif /* HB_OT_VAR_MVAR_TABLE_HH */
115