1#ifndef OT_LAYOUT_GSUB_ALTERNATESET_HH
2#define OT_LAYOUT_GSUB_ALTERNATESET_HH
3
4#include "Common.hh"
5
6namespace OT {
7namespace Layout {
8namespace GSUB_impl {
9
10template <typename Types>
11struct AlternateSet
12{
13 protected:
14 Array16Of<typename Types::HBGlyphID>
15 alternates; /* Array of alternate GlyphIDs--in
16 * arbitrary order */
17 public:
18 DEFINE_SIZE_ARRAY (2, alternates);
19
20 bool sanitize (hb_sanitize_context_t *c) const
21 {
22 TRACE_SANITIZE (this);
23 return_trace (alternates.sanitize (c));
24 }
25
26 bool intersects (const hb_set_t *glyphs) const
27 { return hb_any (alternates, glyphs); }
28
29 void closure (hb_closure_context_t *c) const
30 { c->output->add_array (alternates.arrayZ, alternates.len); }
31
32 void collect_glyphs (hb_collect_glyphs_context_t *c) const
33 { c->output->add_array (alternates.arrayZ, alternates.len); }
34
35 bool apply (hb_ot_apply_context_t *c) const
36 {
37 TRACE_APPLY (this);
38 unsigned int count = alternates.len;
39
40 if (unlikely (!count)) return_trace (false);
41
42 hb_mask_t glyph_mask = c->buffer->cur().mask;
43 hb_mask_t lookup_mask = c->lookup_mask;
44
45 /* Note: This breaks badly if two features enabled this lookup together. */
46 unsigned int shift = hb_ctz (lookup_mask);
47 unsigned int alt_index = ((lookup_mask & glyph_mask) >> shift);
48
49 /* If alt_index is MAX_VALUE, randomize feature if it is the rand feature. */
50 if (alt_index == HB_OT_MAP_MAX_VALUE && c->random)
51 {
52 /* Maybe we can do better than unsafe-to-break all; but since we are
53 * changing random state, it would be hard to track that. Good 'nough. */
54 c->buffer->unsafe_to_break (0, c->buffer->len);
55 alt_index = c->random_number () % count + 1;
56 }
57
58 if (unlikely (alt_index > count || alt_index == 0)) return_trace (false);
59
60 if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
61 {
62 c->buffer->sync_so_far ();
63 c->buffer->message (c->font,
64 "replacing glyph at %u (alternate substitution)",
65 c->buffer->idx);
66 }
67
68 c->replace_glyph (alternates[alt_index - 1]);
69
70 if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
71 {
72 c->buffer->message (c->font,
73 "replaced glyph at %u (alternate substitution)",
74 c->buffer->idx - 1u);
75 }
76
77 return_trace (true);
78 }
79
80 unsigned
81 get_alternates (unsigned start_offset,
82 unsigned *alternate_count /* IN/OUT. May be NULL. */,
83 hb_codepoint_t *alternate_glyphs /* OUT. May be NULL. */) const
84 {
85 if (alternates.len && alternate_count)
86 {
87 + alternates.as_array ().sub_array (start_offset, alternate_count)
88 | hb_sink (hb_array (alternate_glyphs, *alternate_count))
89 ;
90 }
91 return alternates.len;
92 }
93
94 template <typename Iterator,
95 hb_requires (hb_is_source_of (Iterator, hb_codepoint_t))>
96 bool serialize (hb_serialize_context_t *c,
97 Iterator alts)
98 {
99 TRACE_SERIALIZE (this);
100 return_trace (alternates.serialize (c, alts));
101 }
102
103 bool subset (hb_subset_context_t *c) const
104 {
105 TRACE_SUBSET (this);
106 const hb_set_t &glyphset = *c->plan->glyphset_gsub ();
107 const hb_map_t &glyph_map = *c->plan->glyph_map;
108
109 auto it =
110 + hb_iter (alternates)
111 | hb_filter (glyphset)
112 | hb_map (glyph_map)
113 ;
114
115 auto *out = c->serializer->start_embed (*this);
116 return_trace (out->serialize (c->serializer, it) &&
117 out->alternates);
118 }
119};
120
121}
122}
123}
124
125
126#endif /* OT_LAYOUT_GSUB_ALTERNATESET_HH */
127