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
12namespace ots {
13
14bool 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
117bool ots_head_should_serialise(OpenTypeFile *file) {
118  return file->head != NULL;
119}
120
121bool 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
145void ots_head_free(OpenTypeFile *file) {
146  delete file->head;
147}
148
149}  // namespace
150