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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 < 2)
     61     {
     62       if (!len)
     63 	return value;
     64       else /* len == 1*/
     65 	return value - array[0].fromCoord + array[0].toCoord;
     66     }
     67 
     68     if (value <= array[0].fromCoord)
     69       return value - array[0].fromCoord + array[0].toCoord;
     70 
     71     unsigned int i;
     72     unsigned int count = len;
     73     for (i = 1; i < count && value > array[i].fromCoord; i++)
     74       ;
     75 
     76     if (value >= array[i].fromCoord)
     77       return value - array[i].fromCoord + array[i].toCoord;
     78 
     79     if (unlikely (array[i-1].fromCoord == array[i].fromCoord))
     80       return array[i-1].toCoord;
     81 
     82     int denom = array[i].fromCoord - array[i-1].fromCoord;
     83     return array[i-1].toCoord +
     84 	   ((array[i].toCoord - array[i-1].toCoord) *
     85 	    (value - array[i-1].fromCoord) + denom/2) / denom;
     86   }
     87 
     88   DEFINE_SIZE_ARRAY (2, array);
     89 };
     90 
     91 /*
     92  * avar  Axis Variations Table
     93  */
     94 
     95 #define HB_OT_TAG_avar HB_TAG('a','v','a','r')
     96 
     97 struct avar
     98 {
     99   static const hb_tag_t tableTag	= HB_OT_TAG_avar;
    100 
    101   inline bool sanitize (hb_sanitize_context_t *c) const
    102   {
    103     TRACE_SANITIZE (this);
    104     if (unlikely (!(version.sanitize (c) &&
    105 		    version.major == 1 &&
    106 		    c->check_struct (this))))
    107       return_trace (false);
    108 
    109     const SegmentMaps *map = &axisSegmentMapsZ;
    110     unsigned int count = axisCount;
    111     for (unsigned int i = 0; i < count; i++)
    112     {
    113       if (unlikely (!map->sanitize (c)))
    114         return_trace (false);
    115       map = &StructAfter<SegmentMaps> (*map);
    116     }
    117 
    118     return_trace (true);
    119   }
    120 
    121   inline void map_coords (int *coords, unsigned int coords_length) const
    122   {
    123     unsigned int count = MIN<unsigned int> (coords_length, axisCount);
    124 
    125     const SegmentMaps *map = &axisSegmentMapsZ;
    126     for (unsigned int i = 0; i < count; i++)
    127     {
    128       coords[i] = map->map (coords[i]);
    129       map = &StructAfter<SegmentMaps> (*map);
    130     }
    131   }
    132 
    133   protected:
    134   FixedVersion<>version;	/* Version of the avar table
    135 				 * initially set to 0x00010000u */
    136   UINT16	reserved;	/* This field is permanently reserved. Set to 0. */
    137   UINT16	axisCount;	/* The number of variation axes in the font. This
    138 				 * must be the same number as axisCount in the
    139 				 * 'fvar' table. */
    140   SegmentMaps	axisSegmentMapsZ;
    141 
    142   public:
    143   DEFINE_SIZE_MIN (8);
    144 };
    145 
    146 } /* namespace OT */
    147 
    148 
    149 #endif /* HB_OT_VAR_AVAR_TABLE_HH */
    150