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1 /*
2  * Copyright © 2018  Ebrahim Byagowi
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_AAT_LAYOUT_FEAT_TABLE_HH
26 #define HB_AAT_LAYOUT_FEAT_TABLE_HH
27 
28 #include "hb-aat-layout-common.hh"
29 
30 /*
31  * feat -- Feature Name
32  * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6feat.html
33  */
34 #define HB_AAT_TAG_feat HB_TAG('f','e','a','t')
35 
36 
37 namespace AAT {
38 
39 
40 struct SettingName
41 {
42   friend struct FeatureName;
43 
cmpAAT::SettingName44   int cmp (hb_aat_layout_feature_selector_t key) const
45   { return (int) key - (int) setting; }
46 
get_selectorAAT::SettingName47   hb_aat_layout_feature_selector_t get_selector () const
48   { return (hb_aat_layout_feature_selector_t) (unsigned) setting; }
49 
get_infoAAT::SettingName50   void get_info (hb_aat_layout_feature_selector_info_t *s,
51 			hb_aat_layout_feature_selector_t default_selector) const
52   {
53     s->name_id = nameIndex;
54 
55     s->enable = (hb_aat_layout_feature_selector_t) (unsigned int) setting;
56     s->disable = default_selector == HB_AAT_LAYOUT_FEATURE_SELECTOR_INVALID ?
57 		 (hb_aat_layout_feature_selector_t) (s->enable + 1) :
58 		 default_selector;
59 
60     s->reserved = 0;
61   }
62 
sanitizeAAT::SettingName63   bool sanitize (hb_sanitize_context_t *c) const
64   {
65     TRACE_SANITIZE (this);
66     return_trace (likely (c->check_struct (this)));
67   }
68 
69   protected:
70   HBUINT16	setting;	/* The setting. */
71   NameID	nameIndex;	/* The name table index for the setting's name. */
72   public:
73   DEFINE_SIZE_STATIC (4);
74 };
75 DECLARE_NULL_NAMESPACE_BYTES (AAT, SettingName);
76 
77 struct feat;
78 
79 struct FeatureName
80 {
cmpAAT::FeatureName81   int cmp (hb_aat_layout_feature_type_t key) const
82   { return (int) key - (int) feature; }
83 
84   enum {
85     Exclusive	= 0x8000,	/* If set, the feature settings are mutually exclusive. */
86     NotDefault	= 0x4000,	/* If clear, then the setting with an index of 0 in
87 				 * the setting name array for this feature should
88 				 * be taken as the default for the feature
89 				 * (if one is required). If set, then bits 0-15 of this
90 				 * featureFlags field contain the index of the setting
91 				 * which is to be taken as the default. */
92     IndexMask	= 0x00FF	/* If bits 30 and 31 are set, then these sixteen bits
93 				 * indicate the index of the setting in the setting name
94 				 * array for this feature which should be taken
95 				 * as the default. */
96   };
97 
get_selector_infosAAT::FeatureName98   unsigned int get_selector_infos (unsigned int                           start_offset,
99 				   unsigned int                          *selectors_count, /* IN/OUT.  May be NULL. */
100 				   hb_aat_layout_feature_selector_info_t *selectors,       /* OUT.     May be NULL. */
101 				   unsigned int                          *pdefault_index,  /* OUT.     May be NULL. */
102 				   const void *base) const
103   {
104     hb_array_t< const SettingName> settings_table = (base+settingTableZ).as_array (nSettings);
105 
106     static_assert (Index::NOT_FOUND_INDEX == HB_AAT_LAYOUT_NO_SELECTOR_INDEX, "");
107 
108     hb_aat_layout_feature_selector_t default_selector = HB_AAT_LAYOUT_FEATURE_SELECTOR_INVALID;
109     unsigned int default_index = Index::NOT_FOUND_INDEX;
110     if (featureFlags & Exclusive)
111     {
112       default_index = (featureFlags & NotDefault) ? featureFlags & IndexMask : 0;
113       default_selector = settings_table[default_index].get_selector ();
114     }
115     if (pdefault_index)
116       *pdefault_index = default_index;
117 
118     if (selectors_count)
119     {
120       hb_array_t<const SettingName> arr = settings_table.sub_array (start_offset, selectors_count);
121       unsigned int count = arr.len;
122       for (unsigned int i = 0; i < count; i++)
123         settings_table[start_offset + i].get_info (&selectors[i], default_selector);
124     }
125     return settings_table.len;
126   }
127 
get_feature_typeAAT::FeatureName128   hb_aat_layout_feature_type_t get_feature_type () const
129   { return (hb_aat_layout_feature_type_t) (unsigned int) feature; }
130 
get_feature_name_idAAT::FeatureName131   hb_ot_name_id_t get_feature_name_id () const { return nameIndex; }
132 
sanitizeAAT::FeatureName133   bool sanitize (hb_sanitize_context_t *c, const void *base) const
134   {
135     TRACE_SANITIZE (this);
136     return_trace (likely (c->check_struct (this) &&
137 			  (base+settingTableZ).sanitize (c, nSettings)));
138   }
139 
140   protected:
141   HBUINT16	feature;	/* Feature type. */
142   HBUINT16	nSettings;	/* The number of records in the setting name array. */
143   LOffsetTo<UnsizedArrayOf<SettingName>, false>
144 		settingTableZ;	/* Offset in bytes from the beginning of this table to
145 				 * this feature's setting name array. The actual type of
146 				 * record this offset refers to will depend on the
147 				 * exclusivity value, as described below. */
148   HBUINT16	featureFlags;	/* Single-bit flags associated with the feature type. */
149   HBINT16	nameIndex;	/* The name table index for the feature's name.
150 				 * This index has values greater than 255 and
151 				 * less than 32768. */
152   public:
153   DEFINE_SIZE_STATIC (12);
154 };
155 
156 struct feat
157 {
158   enum { tableTag = HB_AAT_TAG_feat };
159 
has_dataAAT::feat160   bool has_data () const { return version.to_int (); }
161 
get_feature_typesAAT::feat162   unsigned int get_feature_types (unsigned int                  start_offset,
163 				  unsigned int                 *count,
164 				  hb_aat_layout_feature_type_t *features) const
165   {
166     unsigned int feature_count = featureNameCount;
167     if (count && *count)
168     {
169       unsigned int len = MIN (feature_count - start_offset, *count);
170       for (unsigned int i = 0; i < len; i++)
171 	features[i] = namesZ[i + start_offset].get_feature_type ();
172       *count = len;
173     }
174     return featureNameCount;
175   }
176 
get_featureAAT::feat177   const FeatureName& get_feature (hb_aat_layout_feature_type_t feature_type) const
178   {
179     return namesZ.bsearch (featureNameCount, feature_type);
180   }
181 
get_feature_name_idAAT::feat182   hb_ot_name_id_t get_feature_name_id (hb_aat_layout_feature_type_t feature) const
183   { return get_feature (feature).get_feature_name_id (); }
184 
get_selector_infosAAT::feat185   unsigned int get_selector_infos (hb_aat_layout_feature_type_t           feature_type,
186 				   unsigned int                           start_offset,
187 				   unsigned int                          *selectors_count, /* IN/OUT.  May be NULL. */
188 				   hb_aat_layout_feature_selector_info_t *selectors,       /* OUT.     May be NULL. */
189 				   unsigned int                          *default_index    /* OUT.     May be NULL. */) const
190   {
191     return get_feature (feature_type).get_selector_infos (start_offset, selectors_count, selectors,
192 							  default_index, this);
193   }
194 
sanitizeAAT::feat195   bool sanitize (hb_sanitize_context_t *c) const
196   {
197     TRACE_SANITIZE (this);
198     return_trace (likely (c->check_struct (this) &&
199 			  version.major == 1 &&
200 			  namesZ.sanitize (c, featureNameCount, this)));
201   }
202 
203   protected:
204   FixedVersion<>version;	/* Version number of the feature name table
205 				 * (0x00010000 for the current version). */
206   HBUINT16	featureNameCount;
207 				/* The number of entries in the feature name array. */
208   HBUINT16	reserved1;	/* Reserved (set to zero). */
209   HBUINT32	reserved2;	/* Reserved (set to zero). */
210   SortedUnsizedArrayOf<FeatureName>
211 		namesZ;		/* The feature name array. */
212   public:
213   DEFINE_SIZE_STATIC (24);
214 };
215 
216 } /* namespace AAT */
217 
218 #endif /* HB_AAT_LAYOUT_FEAT_TABLE_HH */
219