1// Copyright 2015 Google Inc.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14//
15////////////////////////////////////////////////////////////////////////////////
16//
17// TiffDirectory contains an abstraction of an image file directory (IFD) as
18// proposed by the TIFF specification.
19
20#ifndef PIEX_TIFF_DIRECTORY_TIFF_DIRECTORY_H_
21#define PIEX_TIFF_DIRECTORY_TIFF_DIRECTORY_H_
22
23#include <cstdint>
24#include <map>
25#include <string>
26#include <vector>
27
28namespace piex {
29namespace tiff_directory {
30
31enum Endian {
32  kLittleEndian = 0,
33  kBigEndian = 1,
34};
35
36struct Rational {
37  std::uint32_t numerator;
38  std::uint32_t denominator;
39};
40
41struct SRational {
42  std::int32_t numerator;
43  std::int32_t denominator;
44};
45
46enum TiffTypes {
47  TIFF_TYPE_NONE = 0,
48  TIFF_TYPE_BYTE,      /* 8bit unsigned */
49  TIFF_TYPE_ASCII,     /* Ascii string (terminated by \0) */
50  TIFF_TYPE_SHORT,     /* 16bit unsigned  */
51  TIFF_TYPE_LONG,      /* 32bit unsigned  */
52  TIFF_TYPE_RATIONAL,  /* 32bit/32bit unsigned  */
53  TIFF_TYPE_SBYTE,     /* 8bit signed */
54  TIFF_TYPE_UNDEFINED, /* undefined (depend of tag) */
55  TIFF_TYPE_SSHORT,    /* 16bit signed*/
56  TIFF_TYPE_SLONG,     /* 32bit signed  */
57  TIFF_TYPE_SRATIONAL, /* 32bit/32bit signed */
58  TIFF_TYPE_FLOAT,     /* 32-bit IEEE float */
59  TIFF_TYPE_DOUBLE,    /* 64-bit IEEE float */
60  TIFF_IFD,            /* IFD type */
61};
62
63// The TiffDirectory class stores all information necessary to interpret TIFF
64// tags and manages also potential sub directories.
65class TiffDirectory {
66 public:
67  typedef std::uint32_t Tag;
68  typedef std::uint32_t Type;
69
70  explicit TiffDirectory(Endian endianness);
71
72  // Returns true if the directory contains the specified tag.
73  bool Has(const Tag tag) const;
74
75  // Gets the value of a tag of byte vector type.
76  // Returns false if the tag is not part of the directory or if the
77  // type is not BYTE or UNDEFINED.
78  bool Get(const Tag tag, std::vector<std::uint8_t>* value) const;
79
80  // Gets the value of a tag of type "ASCII".
81  // Returns false if the tag is not part of the directory or if its
82  // type is not ASCII.
83  // If *err is not equal to ERR_OK initially, this method does nothing.
84  bool Get(const Tag tag, std::string* value) const;
85
86  // Gets the value of a tag of type "SHORT" or "LONG".
87  // Returns false
88  // - if the tag is not part of the directory or
89  // - if the type is not SHORT or LONG, or
90  // - if, for the non-vector version, the number of elements is unequal to 1.
91  bool Get(const Tag tag, std::uint32_t* value) const;
92  bool Get(const Tag tag, std::vector<std::uint32_t>* value) const;
93
94  // Gets the value of a tag of type "SHORT", "LONG" or "RATIONAL".
95  // Returns false
96  // - if the tag is not part of the directory or
97  // - if the type is not SHORT, LONG or RATIONAL, or
98  // - if, for the non-vector version, the number of elements is unequal to 1.
99  bool Get(const Tag tag, Rational* value) const;
100  bool Get(const Tag tag, std::vector<Rational>* value) const;
101
102  // Gets the value of a tag of type "SSHORT", "SLONG" or "SRATIONAL".
103  // Returns false
104  // - if the tag is not part of the directory or
105  // - if the type is not SSHORT, SLONG or SRATIONAL, or
106  // - if, for the non-vector version, the number of elements is unequal to 1.
107  bool Get(const Tag tag, SRational* value) const;
108  bool Get(const Tag tag, std::vector<SRational>* value) const;
109
110  // Gets the 'offset' to the value data in the file and its 'length' in bytes.
111  // Returns false if the 'tag' is not part of the directory or if its type does
112  // not match the desired 'type'.
113  bool GetOffsetAndLength(const Tag tag, const Type type, std::uint32_t* offset,
114                          std::uint32_t* length) const;
115
116  // Adds a tag to the directory, setting its type, number of elements
117  // ('count'), the offset to the binary data in the file ('offset') and the
118  // associated binary data ('value'). The binary data is encoded according to
119  // the TIFF specification with the endianness that was specified when this
120  // object was constructed. The caller must ensure that the size of 'value' and
121  // the data it contains are consistent with 'type' and 'count'. It is not
122  // legal to call this method with a tag that is already contained in the
123  // directory.
124  void AddEntry(const Tag tag, const Type type, const std::uint32_t count,
125                const std::uint32_t offset,
126                const std::vector<std::uint8_t>& value);
127
128  // Add a subdirectory to the directory.
129  void AddSubDirectory(const TiffDirectory& sub_directory);
130
131  // Returns a vector of all subdirectories contained in this directory.
132  const std::vector<TiffDirectory>& GetSubDirectories() const;
133
134 private:
135  struct DirectoryEntry {
136    Type type;
137    std::uint32_t count;   // The number of values of type, not a byte count.
138    std::uint32_t offset;  // Offset of the entry's data in the file. '0' means
139                           // the offset is not set.
140    std::vector<std::uint8_t> value;
141  };
142
143  const DirectoryEntry* Find(const Tag tag) const;
144
145  std::map<Tag, DirectoryEntry> directory_entries_;
146  std::vector<Tag> tag_order_;
147  std::vector<TiffDirectory> sub_directories_;
148  Endian endian_;
149};
150
151// Returns the number of bytes a single value of 'type' requires; this is
152// guaranteed to be in the range of 0 to 8.
153// Returns 0 if 'type' is TIFF_TYPE_NONE or invalid. Sets 'success' to false if
154// 'type' is invalid. If you are not interested in 'success' you can set it to
155// a nullptr.
156size_t SizeOfType(const TiffDirectory::Type type, bool* success);
157
158}  // namespace tiff_directory
159}  // namespace piex
160
161#endif  // PIEX_TIFF_DIRECTORY_TIFF_DIRECTORY_H_
162