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 {
  38   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   ULONG         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 
  63   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 
  74   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:
  88   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   USHORT        reserved;       /* Not used; set to 0. */
  99   USHORT        valueRecordSize;/* The size in bytes of each value record —
 100                                  * must be greater than zero. */
 101   USHORT        valueRecordCount;/* The number of value records — may be zero. */
 102   OffsetTo<VariationStore>
 103                 varStore;       /* Offset to item variation store table. */
 104   BYTE          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 */