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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_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 {
     37   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 {
     54   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)
     61       return value;
     62 
     63     if (value <= array[0].fromCoord)
     64       return value - array[0].fromCoord + array[0].toCoord;
     65 
     66     unsigned int i;
     67     unsigned int count = len;
     68     for (i = 1; i < count && value > array[i].fromCoord; i++)
     69       ;
     70 
     71     if (value >= array[i].fromCoord)
     72       return value - array[i].fromCoord + array[i].toCoord;
     73 
     74     if (unlikely (array[i-1].fromCoord == array[i].fromCoord))
     75       return array[i-1].toCoord;
     76 
     77     int denom = array[i].fromCoord - array[i-1].fromCoord;
     78     return array[i-1].toCoord +
     79 	   (array[i].toCoord - array[i-1].toCoord) *
     80 	   (value - array[i-1].fromCoord + denom/2) / denom;
     81   }
     82 
     83   DEFINE_SIZE_ARRAY (2, array);
     84 };
     85 
     86 /*
     87  * avar  Axis Variations Table
     88  */
     89 
     90 #define HB_OT_TAG_avar HB_TAG('a','v','a','r')
     91 
     92 struct avar
     93 {
     94   static const hb_tag_t tableTag	= HB_OT_TAG_avar;
     95 
     96   inline bool sanitize (hb_sanitize_context_t *c) const
     97   {
     98     TRACE_SANITIZE (this);
     99     if (unlikely (!(version.sanitize (c) &&
    100 		    version.major == 1 &&
    101 		    c->check_struct (this))))
    102       return_trace (false);
    103 
    104     const SegmentMaps *map = &axisSegmentMapsZ;
    105     unsigned int count = axisCount;
    106     for (unsigned int i = 0; i < count; i++)
    107     {
    108       if (unlikely (!map->sanitize (c)))
    109         return_trace (false);
    110       map = &StructAfter<SegmentMaps> (*map);
    111     }
    112 
    113     return_trace (true);
    114   }
    115 
    116   inline void map_coords (int *coords, unsigned int coords_length) const
    117   {
    118     unsigned int count = MIN<unsigned int> (coords_length, axisCount);
    119 
    120     const SegmentMaps *map = &axisSegmentMapsZ;
    121     for (unsigned int i = 0; i < count; i++)
    122     {
    123       coords[i] = map->map (coords[i]);
    124       map = &StructAfter<SegmentMaps> (*map);
    125     }
    126   }
    127 
    128   protected:
    129   FixedVersion<>version;	/* Version of the avar table
    130 				 * initially set to 0x00010000u */
    131   USHORT	reserved;	/* This field is permanently reserved. Set to 0. */
    132   USHORT	axisCount;	/* The number of variation axes in the font. This
    133 				 * must be the same number as axisCount in the
    134 				 * 'fvar' table. */
    135   SegmentMaps	axisSegmentMapsZ;
    136 
    137   public:
    138   DEFINE_SIZE_MIN (8);
    139 };
    140 
    141 } /* namespace OT */
    142 
    143 
    144 #endif /* HB_OT_VAR_AVAR_TABLE_HH */
    145