1 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "head.h"
6
7 #include <cstring>
8
9 // head - Font Header
10 // http://www.microsoft.com/opentype/otspec/head.htm
11
12 namespace ots {
13
ots_head_parse(OpenTypeFile * file,const uint8_t * data,size_t length)14 bool ots_head_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
15 Buffer table(data, length);
16 file->head = new OpenTypeHEAD;
17
18 uint32_t version = 0;
19 if (!table.ReadU32(&version) ||
20 !table.ReadU32(&file->head->revision)) {
21 return OTS_FAILURE();
22 }
23
24 if (version >> 16 != 1) {
25 return OTS_FAILURE();
26 }
27
28 // Skip the checksum adjustment
29 if (!table.Skip(4)) {
30 return OTS_FAILURE();
31 }
32
33 uint32_t magic;
34 if (!table.ReadTag(&magic) ||
35 std::memcmp(&magic, "\x5F\x0F\x3C\xF5", 4)) {
36 return OTS_FAILURE();
37 }
38
39 if (!table.ReadU16(&file->head->flags)) {
40 return OTS_FAILURE();
41 }
42
43 // We allow bits 0..4, 11..13
44 file->head->flags &= 0x381f;
45
46 if (!table.ReadU16(&file->head->ppem)) {
47 return OTS_FAILURE();
48 }
49
50 // ppem must be in range
51 if (file->head->ppem < 16 ||
52 file->head->ppem > 16384) {
53 return OTS_FAILURE();
54 }
55
56 // ppem must be a power of two
57 #if 0
58 // We don't call ots_failure() for now since lots of TrueType fonts are
59 // not following this rule. Putting OTS_WARNING here is too noisy.
60 if ((file->head->ppem - 1) & file->head->ppem) {
61 return OTS_FAILURE();
62 }
63 #endif
64
65 if (!table.ReadR64(&file->head->created) ||
66 !table.ReadR64(&file->head->modified)) {
67 return OTS_FAILURE();
68 }
69
70 if (!table.ReadS16(&file->head->xmin) ||
71 !table.ReadS16(&file->head->ymin) ||
72 !table.ReadS16(&file->head->xmax) ||
73 !table.ReadS16(&file->head->ymax)) {
74 return OTS_FAILURE();
75 }
76
77 if (file->head->xmin > file->head->xmax) {
78 return OTS_FAILURE();
79 }
80 if (file->head->ymin > file->head->ymax) {
81 return OTS_FAILURE();
82 }
83
84 if (!table.ReadU16(&file->head->mac_style)) {
85 return OTS_FAILURE();
86 }
87
88 // We allow bits 0..6
89 file->head->mac_style &= 0x7f;
90
91 if (!table.ReadU16(&file->head->min_ppem)) {
92 return OTS_FAILURE();
93 }
94
95 // We don't care about the font direction hint
96 if (!table.Skip(2)) {
97 return OTS_FAILURE();
98 }
99
100 if (!table.ReadS16(&file->head->index_to_loc_format)) {
101 return OTS_FAILURE();
102 }
103 if (file->head->index_to_loc_format < 0 ||
104 file->head->index_to_loc_format > 1) {
105 return OTS_FAILURE();
106 }
107
108 int16_t glyph_data_format;
109 if (!table.ReadS16(&glyph_data_format) ||
110 glyph_data_format) {
111 return OTS_FAILURE();
112 }
113
114 return true;
115 }
116
ots_head_should_serialise(OpenTypeFile * file)117 bool ots_head_should_serialise(OpenTypeFile *file) {
118 return file->head != NULL;
119 }
120
ots_head_serialise(OTSStream * out,OpenTypeFile * file)121 bool ots_head_serialise(OTSStream *out, OpenTypeFile *file) {
122 if (!out->WriteU32(0x00010000) ||
123 !out->WriteU32(file->head->revision) ||
124 !out->WriteU32(0) || // check sum not filled in yet
125 !out->WriteU32(0x5F0F3CF5) ||
126 !out->WriteU16(file->head->flags) ||
127 !out->WriteU16(file->head->ppem) ||
128 !out->WriteR64(file->head->created) ||
129 !out->WriteR64(file->head->modified) ||
130 !out->WriteS16(file->head->xmin) ||
131 !out->WriteS16(file->head->ymin) ||
132 !out->WriteS16(file->head->xmax) ||
133 !out->WriteS16(file->head->ymax) ||
134 !out->WriteU16(file->head->mac_style) ||
135 !out->WriteU16(file->head->min_ppem) ||
136 !out->WriteS16(2) ||
137 !out->WriteS16(file->head->index_to_loc_format) ||
138 !out->WriteS16(0)) {
139 return OTS_FAILURE();
140 }
141
142 return true;
143 }
144
ots_head_free(OpenTypeFile * file)145 void ots_head_free(OpenTypeFile *file) {
146 delete file->head;
147 }
148
149 } // namespace
150