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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_HVAR_TABLE_HH
28 #define HB_OT_VAR_HVAR_TABLE_HH
29 
30 #include "hb-ot-layout-common.hh"
31 
32 
33 namespace OT {
34 
35 
36 struct DeltaSetIndexMap
37 {
sanitizeOT::DeltaSetIndexMap38   bool sanitize (hb_sanitize_context_t *c) const
39   {
40     TRACE_SANITIZE (this);
41     return_trace (c->check_struct (this) &&
42 		  c->check_range (mapDataZ.arrayZ,
43 				  mapCount,
44 				  get_width ()));
45   }
46 
mapOT::DeltaSetIndexMap47   unsigned int map (unsigned int v) const /* Returns 16.16 outer.inner. */
48   {
49     /* If count is zero, pass value unchanged.  This takes
50      * care of direct mapping for advance map. */
51     if (!mapCount)
52       return v;
53 
54     if (v >= mapCount)
55       v = mapCount - 1;
56 
57     unsigned int u = 0;
58     { /* Fetch it. */
59       unsigned int w = get_width ();
60       const HBUINT8 *p = mapDataZ.arrayZ + w * v;
61       for (; w; w--)
62 	u = (u << 8) + *p++;
63     }
64 
65     { /* Repack it. */
66       unsigned int n = get_inner_bitcount ();
67       unsigned int outer = u >> n;
68       unsigned int inner = u & ((1 << n) - 1);
69       u = (outer<<16) | inner;
70     }
71 
72     return u;
73   }
74 
75   protected:
get_widthOT::DeltaSetIndexMap76   unsigned int get_width () const          { return ((format >> 4) & 3) + 1; }
77 
get_inner_bitcountOT::DeltaSetIndexMap78   unsigned int get_inner_bitcount () const { return (format & 0xF) + 1; }
79 
80   protected:
81   HBUINT16	format;		/* A packed field that describes the compressed
82 				 * representation of delta-set indices. */
83   HBUINT16	mapCount;	/* The number of mapping entries. */
84   UnsizedArrayOf<HBUINT8>
85  		mapDataZ;	/* The delta-set index mapping data. */
86 
87   public:
88   DEFINE_SIZE_ARRAY (4, mapDataZ);
89 };
90 
91 
92 /*
93  * HVAR -- Horizontal Metrics Variations
94  * https://docs.microsoft.com/en-us/typography/opentype/spec/hvar
95  * VVAR -- Vertical Metrics Variations
96  * https://docs.microsoft.com/en-us/typography/opentype/spec/vvar
97  */
98 #define HB_OT_TAG_HVAR HB_TAG('H','V','A','R')
99 #define HB_OT_TAG_VVAR HB_TAG('V','V','A','R')
100 
101 struct HVARVVAR
102 {
103   enum { HVARTag = HB_OT_TAG_HVAR };
104   enum { VVARTag = HB_OT_TAG_VVAR };
105 
sanitizeOT::HVARVVAR106   bool sanitize (hb_sanitize_context_t *c) const
107   {
108     TRACE_SANITIZE (this);
109     return_trace (version.sanitize (c) &&
110 		  likely (version.major == 1) &&
111 		  varStore.sanitize (c, this) &&
112 		  advMap.sanitize (c, this) &&
113 		  lsbMap.sanitize (c, this) &&
114 		  rsbMap.sanitize (c, this));
115   }
116 
get_advance_varOT::HVARVVAR117   float get_advance_var (hb_codepoint_t glyph,
118 			 const int *coords, unsigned int coord_count) const
119   {
120     unsigned int varidx = (this+advMap).map (glyph);
121     return (this+varStore).get_delta (varidx, coords, coord_count);
122   }
123 
has_sidebearing_deltasOT::HVARVVAR124   bool has_sidebearing_deltas () const { return lsbMap && rsbMap; }
125 
126   protected:
127   FixedVersion<>version;	/* Version of the metrics variation table
128 				 * initially set to 0x00010000u */
129   LOffsetTo<VariationStore>
130 		varStore;	/* Offset to item variation store table. */
131   LOffsetTo<DeltaSetIndexMap>
132 		advMap;		/* Offset to advance var-idx mapping. */
133   LOffsetTo<DeltaSetIndexMap>
134 		lsbMap;		/* Offset to lsb/tsb var-idx mapping. */
135   LOffsetTo<DeltaSetIndexMap>
136 		rsbMap;		/* Offset to rsb/bsb var-idx mapping. */
137 
138   public:
139   DEFINE_SIZE_STATIC (20);
140 };
141 
142 struct HVAR : HVARVVAR {
143   enum { tableTag = HB_OT_TAG_HVAR };
144 };
145 struct VVAR : HVARVVAR {
146   enum { tableTag = HB_OT_TAG_VVAR };
147 
sanitizeOT::VVAR148   bool sanitize (hb_sanitize_context_t *c) const
149   {
150     TRACE_SANITIZE (this);
151     return_trace (static_cast<const HVARVVAR *> (this)->sanitize (c) &&
152 		  vorgMap.sanitize (c, this));
153   }
154 
155   protected:
156   LOffsetTo<DeltaSetIndexMap>
157 		vorgMap;	/* Offset to vertical-origin var-idx mapping. */
158 
159   public:
160   DEFINE_SIZE_STATIC (24);
161 };
162 
163 } /* namespace OT */
164 
165 
166 #endif /* HB_OT_VAR_HVAR_TABLE_HH */
167