gfx/harfbuzz/src/hb-subset-instancer-solver.hh

   1 /*
   2  * Copyright © 2023  Behdad Esfahbod
   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
  25 #ifndef HB_SUBSET_INSTANCER_SOLVER_HH
  26 #define HB_SUBSET_INSTANCER_SOLVER_HH
  27
  28 #include "hb.hh"
  29
  30 /* pre-normalized distances */
  31 struct TripleDistances
  32 {
  33   TripleDistances (): negative (1.f), positive (1.f) {}
  34   TripleDistances (float neg_, float pos_): negative (neg_), positive (pos_) {}
  35   TripleDistances (float min, float default_, float max)
  36   {
  37     negative = default_ - min;
  38     positive = max - default_;
  39   }
  40
  41   float negative;
  42   float positive;
  43 };
  44
  45 struct Triple {
  46
  47   Triple () :
  48     minimum (0.f), middle (0.f), maximum (0.f) {}
  49
  50   Triple (float minimum_, float middle_, float maximum_) :
  51     minimum (minimum_), middle (middle_), maximum (maximum_) {}
  52
  53   bool operator == (const Triple &o) const
  54   {
  55     return minimum == o.minimum &&
  56            middle  == o.middle  &&
  57            maximum == o.maximum;
  58   }
  59
  60   bool operator != (const Triple o) const
  61   { return !(*this == o); }
  62
  63   bool is_point () const
  64   { return minimum == middle && middle == maximum; }
  65
  66   bool contains (float point) const
  67   { return minimum <= point && point <= maximum; }
  68
  69   /* from hb_array_t hash ()*/
  70   uint32_t hash () const
  71   {
  72     uint32_t current = /*cbf29ce4*/0x84222325;
  73     current = current ^ hb_hash (minimum);
  74     current = current * 16777619;
  75
  76     current = current ^ hb_hash (middle);
  77     current = current * 16777619;
  78
  79     current = current ^ hb_hash (maximum);
  80     current = current * 16777619;
  81     return current;
  82   }
  83
  84
  85   float minimum;
  86   float middle;
  87   float maximum;
  88 };
  89
  90 using result_item_t = hb_pair_t<float, Triple>;
  91 using result_t = hb_vector_t<result_item_t>;
  92
  93 /* renormalize a normalized value v to the range of an axis,
  94  * considering the prenormalized distances as well as the new axis limits.
  95  * Ported from fonttools */
  96 HB_INTERNAL float renormalizeValue (float v, const Triple &triple,
  97                                     const TripleDistances &triple_distances,
  98                                     bool extrapolate = true);
  99 /* Given a tuple (lower,peak,upper) "tent" and new axis limits
 100  * (axisMin,axisDefault,axisMax), solves how to represent the tent
 101  * under the new axis configuration.  All values are in normalized
 102  * -1,0,+1 coordinate system. Tent values can be outside this range.
 103  *
 104  * Return value: a list of tuples. Each tuple is of the form
 105  * (scalar,tent), where scalar is a multipler to multiply any
 106  * delta-sets by, and tent is a new tent for that output delta-set.
 107  * If tent value is Triple{}, that is a special deltaset that should
 108  * be always-enabled (called "gain").
 109  */
 110 HB_INTERNAL result_t rebase_tent (Triple tent, Triple axisLimit, TripleDistances axis_triple_distances);
 111
 112 #endif /* HB_SUBSET_INSTANCER_SOLVER_HH */