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 {
  38   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 
  63   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 
  76   float get_var (hb_tag_t tag,
  77                  const int *coords, unsigned int coord_count) const
  78   {
  79     const VariationValueRecord *record;
  80     record = (VariationValueRecord *) bsearch (&tag, valuesZ.arrayZ,
  81                                                valueRecordCount, valueRecordSize,
  82                                                tag_compare);
  83     if (!record)
  84       return 0.;
  85 
  86     return (this+varStore).get_delta (record->varIdx, coords, coord_count);
  87   }
  88 
  89 protected:
  90   static int tag_compare (const void *pa, const void *pb)
  91   {
  92     const hb_tag_t *a = (const hb_tag_t *) pa;
  93     const Tag *b = (const Tag *) pb;
  94     return b->cmp (*a);
  95   }
  96 
  97   protected:
  98   FixedVersion<>version;        /* Version of the metrics variation table
  99                                  * initially set to 0x00010000u */
 100   HBUINT16      reserved;       /* Not used; set to 0. */
 101   HBUINT16      valueRecordSize;/* The size in bytes of each value record —
 102                                  * must be greater than zero. */
 103   HBUINT16      valueRecordCount;/* The number of value records — may be zero. */
 104   OffsetTo<VariationStore>
 105                 varStore;       /* Offset to item variation store table. */
 106   UnsizedArrayOf<HBUINT8>
 107                 valuesZ;        /* Array of value records. The records must be
 108                                  * in binary order of their valueTag field. */
 109 
 110   public:
 111   DEFINE_SIZE_ARRAY (12, valuesZ);
 112 };
 113 
 114 } /* namespace OT */
 115 
 116 
 117 #endif /* HB_OT_VAR_MVAR_TABLE_HH */