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.hh"
31 
32 
33 namespace OT {
34 
35 
36 struct VariationValueRecord
37 {
sanitizeOT::VariationValueRecord38   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   HBUINT32		varIdx;		/* Outer/inner index into VariationStore item. */
47 
48   public:
49   DEFINE_SIZE_STATIC (8);
50 };
51 
52 
53 /*
54  * MVAR -- Metrics Variations
55  * https://docs.microsoft.com/en-us/typography/opentype/spec/mvar
56  */
57 #define HB_OT_TAG_MVAR HB_TAG('M','V','A','R')
58 
59 struct MVAR
60 {
61   static constexpr hb_tag_t tableTag = HB_OT_TAG_MVAR;
62 
sanitizeOT::MVAR63   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_range (valuesZ.arrayZ,
72 				  valueRecordCount,
73 				  valueRecordSize));
74   }
75 
get_varOT::MVAR76   float get_var (hb_tag_t tag,
77 		 const int *coords, unsigned int coord_count) const
78   {
79     const VariationValueRecord *record;
80     record = (VariationValueRecord *) hb_bsearch (tag,
81 						  (const VariationValueRecord *)
82 						    (const HBUINT8 *) valuesZ,
83 						  valueRecordCount, valueRecordSize,
84 						  tag_compare);
85     if (!record)
86       return 0.;
87 
88     return (this+varStore).get_delta (record->varIdx, coords, coord_count);
89   }
90 
91 protected:
tag_compareOT::MVAR92   static int tag_compare (const void *pa, const void *pb)
93   {
94     const hb_tag_t *a = (const hb_tag_t *) pa;
95     const Tag *b = (const Tag *) pb;
96     return b->cmp (*a);
97   }
98 
99   protected:
100   FixedVersion<>version;	/* Version of the metrics variation table
101 				 * initially set to 0x00010000u */
102   HBUINT16	reserved;	/* Not used; set to 0. */
103   HBUINT16	valueRecordSize;/* The size in bytes of each value record —
104 				 * must be greater than zero. */
105   HBUINT16	valueRecordCount;/* The number of value records — may be zero. */
106   OffsetTo<VariationStore>
107 		varStore;	/* Offset to item variation store table. */
108   UnsizedArrayOf<HBUINT8>
109 		valuesZ;	/* Array of value records. The records must be
110 				 * in binary order of their valueTag field. */
111 
112   public:
113   DEFINE_SIZE_ARRAY (12, valuesZ);
114 };
115 
116 } /* namespace OT */
117 
118 
119 #endif /* HB_OT_VAR_MVAR_TABLE_HH */
120