blob: 37c6ce99e49aecb122bc543ff020a1908b1da4df (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
/*
* Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Optional.h>
#include <LibTTF/Cmap.h>
namespace TTF {
extern u16 be_u16(const u8* ptr);
extern u32 be_u32(const u8* ptr);
extern i16 be_i16(const u8* ptr);
Cmap::Subtable::Platform Cmap::Subtable::platform_id() const
{
switch (m_raw_platform_id) {
case 0:
return Platform::Unicode;
case 1:
return Platform::Macintosh;
case 3:
return Platform::Windows;
case 4:
return Platform::Custom;
default:
VERIFY_NOT_REACHED();
}
}
Cmap::Subtable::Format Cmap::Subtable::format() const
{
switch (be_u16(m_slice.offset_pointer(0))) {
case 0:
return Format::ByteEncoding;
case 2:
return Format::HighByte;
case 4:
return Format::SegmentToDelta;
case 6:
return Format::TrimmedTable;
case 8:
return Format::Mixed16And32;
case 10:
return Format::TrimmedArray;
case 12:
return Format::SegmentedCoverage;
case 13:
return Format::ManyToOneRange;
case 14:
return Format::UnicodeVariationSequences;
default:
VERIFY_NOT_REACHED();
}
}
u32 Cmap::num_subtables() const
{
return be_u16(m_slice.offset_pointer((u32)Offsets::NumTables));
}
Optional<Cmap::Subtable> Cmap::subtable(u32 index) const
{
if (index >= num_subtables()) {
return {};
}
u32 record_offset = (u32)Sizes::TableHeader + index * (u32)Sizes::EncodingRecord;
u16 platform_id = be_u16(m_slice.offset_pointer(record_offset));
u16 encoding_id = be_u16(m_slice.offset_pointer(record_offset + (u32)Offsets::EncodingRecord_EncodingID));
u32 subtable_offset = be_u32(m_slice.offset_pointer(record_offset + (u32)Offsets::EncodingRecord_Offset));
VERIFY(subtable_offset < m_slice.size());
auto subtable_slice = ReadonlyBytes(m_slice.offset_pointer(subtable_offset), m_slice.size() - subtable_offset);
return Subtable(subtable_slice, platform_id, encoding_id);
}
// FIXME: This only handles formats 4 (SegmentToDelta) and 12 (SegmentedCoverage) for now.
u32 Cmap::Subtable::glyph_id_for_code_point(u32 code_point) const
{
switch (format()) {
case Format::SegmentToDelta:
return glyph_id_for_code_point_table_4(code_point);
case Format::SegmentedCoverage:
return glyph_id_for_code_point_table_12(code_point);
default:
return 0;
}
}
u32 Cmap::Subtable::glyph_id_for_code_point_table_4(u32 code_point) const
{
u32 segcount_x2 = be_u16(m_slice.offset_pointer((u32)Table4Offsets::SegCountX2));
if (m_slice.size() < segcount_x2 * (u32)Table4Sizes::NonConstMultiplier + (u32)Table4Sizes::Constant) {
return 0;
}
for (u32 offset = 0; offset < segcount_x2; offset += 2) {
u32 end_code_point = be_u16(m_slice.offset_pointer((u32)Table4Offsets::EndConstBase + offset));
if (code_point > end_code_point) {
continue;
}
u32 start_code_point = be_u16(m_slice.offset_pointer((u32)Table4Offsets::StartConstBase + segcount_x2 + offset));
if (code_point < start_code_point) {
break;
}
u32 delta = be_u16(m_slice.offset_pointer((u32)Table4Offsets::DeltaConstBase + segcount_x2 * 2 + offset));
u32 range = be_u16(m_slice.offset_pointer((u32)Table4Offsets::RangeConstBase + segcount_x2 * 3 + offset));
if (range == 0) {
return (code_point + delta) & 0xffff;
}
u32 glyph_offset = (u32)Table4Offsets::GlyphOffsetConstBase + segcount_x2 * 3 + offset + range + (code_point - start_code_point) * 2;
VERIFY(glyph_offset + 2 <= m_slice.size());
return (be_u16(m_slice.offset_pointer(glyph_offset)) + delta) & 0xffff;
}
return 0;
}
u32 Cmap::Subtable::glyph_id_for_code_point_table_12(u32 code_point) const
{
u32 num_groups = be_u32(m_slice.offset_pointer((u32)Table12Offsets::NumGroups));
VERIFY(m_slice.size() >= (u32)Table12Sizes::Header + (u32)Table12Sizes::Record * num_groups);
for (u32 offset = 0; offset < num_groups * (u32)Table12Sizes::Record; offset += (u32)Table12Sizes::Record) {
u32 start_code_point = be_u32(m_slice.offset_pointer((u32)Table12Offsets::Record_StartCode + offset));
if (code_point < start_code_point) {
break;
}
u32 end_code_point = be_u32(m_slice.offset_pointer((u32)Table12Offsets::Record_EndCode + offset));
if (code_point > end_code_point) {
continue;
}
u32 glyph_offset = be_u32(m_slice.offset_pointer((u32)Table12Offsets::Record_StartGlyph + offset));
return code_point - start_code_point + glyph_offset;
}
return 0;
}
u32 Cmap::glyph_id_for_code_point(u32 code_point) const
{
auto opt_subtable = subtable(m_active_index);
if (!opt_subtable.has_value()) {
return 0;
}
auto subtable = opt_subtable.value();
return subtable.glyph_id_for_code_point(code_point);
}
Optional<Cmap> Cmap::from_slice(const ReadonlyBytes& slice)
{
if (slice.size() < (size_t)Sizes::TableHeader) {
return {};
}
return Cmap(slice);
}
}
|
