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_HVAR_TABLE_HH
28#define HB_OT_VAR_HVAR_TABLE_HH
29
30#include "hb-ot-layout-common-private.hh"
31
32
33namespace OT {
34
35
36struct DeltaSetIndexMap
37{
38  inline bool sanitize (hb_sanitize_context_t *c) const
39  {
40    TRACE_SANITIZE (this);
41    return_trace (c->check_struct (this) &&
42		  c->check_array (mapData, get_width (), mapCount));
43  }
44
45  unsigned int map (unsigned int v) const /* Returns 16.16 outer.inner. */
46  {
47    /* If count is zero, pass value unchanged.  This takes
48     * care of direct mapping for advance map. */
49    if (!mapCount)
50      return v;
51
52    if (v >= mapCount)
53      v = mapCount - 1;
54
55    unsigned int u = 0;
56    { /* Fetch it. */
57      unsigned int w = get_width ();
58      const UINT8 *p = mapData + w * v;
59      for (; w; w--)
60	u = (u << 8) + *p++;
61    }
62
63    { /* Repack it. */
64      unsigned int n = get_inner_bitcount ();
65      unsigned int outer = u >> n;
66      unsigned int inner = u & ((1 << n) - 1);
67      u = (outer<<16) | inner;
68    }
69
70    return u;
71  }
72
73  protected:
74  inline unsigned int get_width (void) const
75  { return ((format >> 4) & 3) + 1; }
76
77  inline unsigned int get_inner_bitcount (void) const
78  { return (format & 0xF) + 1; }
79
80  protected:
81  UINT16	format;		/* A packed field that describes the compressed
82				 * representation of delta-set indices. */
83  UINT16	mapCount;	/* The number of mapping entries. */
84  UINT8		mapData[VAR];	/* The delta-set index mapping data. */
85
86  public:
87  DEFINE_SIZE_ARRAY (4, mapData);
88};
89
90
91/*
92 * HVAR -- The Horizontal Metrics Variations Table
93 * VVAR -- The Vertical Metrics Variations Table
94 */
95
96#define HB_OT_TAG_HVAR HB_TAG('H','V','A','R')
97#define HB_OT_TAG_VVAR HB_TAG('V','V','A','R')
98
99struct HVARVVAR
100{
101  static const hb_tag_t HVARTag	= HB_OT_TAG_HVAR;
102  static const hb_tag_t VVARTag	= HB_OT_TAG_VVAR;
103
104  inline bool sanitize (hb_sanitize_context_t *c) const
105  {
106    TRACE_SANITIZE (this);
107    return_trace (version.sanitize (c) &&
108		  likely (version.major == 1) &&
109		  varStore.sanitize (c, this) &&
110		  advMap.sanitize (c, this) &&
111		  lsbMap.sanitize (c, this) &&
112		  rsbMap.sanitize (c, this));
113  }
114
115  inline float get_advance_var (hb_codepoint_t glyph,
116				int *coords, unsigned int coord_count) const
117  {
118    unsigned int varidx = (this+advMap).map (glyph);
119    return (this+varStore).get_delta (varidx, coords, coord_count);
120  }
121
122  inline bool has_sidebearing_deltas (void) const
123  { return lsbMap && rsbMap; }
124
125  protected:
126  FixedVersion<>version;	/* Version of the metrics variation table
127				 * initially set to 0x00010000u */
128  LOffsetTo<VariationStore>
129		varStore;	/* Offset to item variation store table. */
130  LOffsetTo<DeltaSetIndexMap>
131		advMap;		/* Offset to advance var-idx mapping. */
132  LOffsetTo<DeltaSetIndexMap>
133		lsbMap;		/* Offset to lsb/tsb var-idx mapping. */
134  LOffsetTo<DeltaSetIndexMap>
135		rsbMap;		/* Offset to rsb/bsb var-idx mapping. */
136
137  public:
138  DEFINE_SIZE_STATIC (20);
139};
140
141struct HVAR : HVARVVAR {
142  static const hb_tag_t tableTag	= HB_OT_TAG_HVAR;
143};
144struct VVAR : HVARVVAR {
145  static const hb_tag_t tableTag	= HB_OT_TAG_VVAR;
146
147  inline bool sanitize (hb_sanitize_context_t *c) const
148  {
149    TRACE_SANITIZE (this);
150    return_trace (static_cast<const HVARVVAR *> (this)->sanitize (c) &&
151		  vorgMap.sanitize (c, this));
152  }
153
154  protected:
155  LOffsetTo<DeltaSetIndexMap>
156		vorgMap;	/* Offset to vertical-origin var-idx mapping. */
157
158  public:
159  DEFINE_SIZE_STATIC (24);
160};
161
162} /* namespace OT */
163
164
165#endif /* HB_OT_VAR_HVAR_TABLE_HH */
166