TiffHelpers.h revision 482343e68853e137c293d4db1e861353ab483ab7 
1/*
2 * Copyright 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef IMG_UTILS_TIFF_HELPERS_H
18#define IMG_UTILS_TIFF_HELPERS_H
19
20#include <stdint.h>
21
22namespace android {
23namespace img_utils {
24
25const uint8_t ZERO_WORD[] = {0, 0, 0, 0};
26
27#define BAIL_ON_FAIL(x, flag) \
28    if (((flag) = (x)) != OK) return flag;
29
30#define BYTES_TILL_WORD(index) \
31    ((TIFF_WORD_SIZE - ((index) % TIFF_WORD_SIZE)) % TIFF_WORD_SIZE)
32
33#define WORD_ALIGN(count) \
34    count += BYTES_TILL_WORD(count);
35
36#define ZERO_TILL_WORD(output, index, ret) \
37    { \
38        size_t remaining = BYTES_TILL_WORD(index); \
39        if (remaining > 0) { \
40            BAIL_ON_FAIL((output)->write(ZERO_WORD, 0, remaining), ret); \
41        } \
42    }
43
44/**
45 * Basic TIFF header constants.
46 */
47enum {
48    BAD_OFFSET = 0,
49    TIFF_WORD_SIZE = 4, // Size in bytes
50    IFD_HEADER_SIZE = 2, // Size in bytes
51    IFD_FOOTER_SIZE = 4, // Size in bytes
52    TIFF_ENTRY_SIZE = 12, // Size in bytes
53    MAX_IFD_ENTRIES = UINT16_MAX,
54    FILE_HEADER_SIZE = 8, // Size in bytes
55    ENDIAN_MARKER_SIZE = 2, // Size in bytes
56    TIFF_MARKER_SIZE = 2, // Size in bytes
57    OFFSET_MARKER_SIZE = 4, // Size in bytes
58    TIFF_FILE_MARKER = 42,
59    BIG_ENDIAN_MARKER = 0x4D4Du,
60    LITTLE_ENDIAN_MARKER = 0x4949u
61};
62
63/**
64 * Constants for the TIFF tag types.
65 */
66enum TagType {
67    UNKNOWN_TAGTYPE = 0,
68    BYTE=1,
69    ASCII,
70    SHORT,
71    LONG,
72    RATIONAL,
73    SBYTE,
74    UNDEFINED,
75    SSHORT,
76    SLONG,
77    SRATIONAL,
78    FLOAT,
79    DOUBLE
80};
81
82/**
83 * Sizes of the TIFF entry fields (in bytes).
84 */
85enum {
86    TAG_SIZE = 2,
87    TYPE_SIZE = 2,
88    COUNT_SIZE = 4,
89    OFFSET_SIZE = 4
90};
91
92/**
93 * Convenience IFD id constants.
94 */
95enum {
96    IFD_0 = 0,
97    RAW_IFD,
98    PROFILE_IFD,
99    PREVIEW_IFD
100};
101
102inline size_t getTypeSize(TagType type) {
103    switch(type) {
104        case UNDEFINED:
105        case ASCII:
106        case BYTE:
107        case SBYTE:
108            return 1;
109        case SHORT:
110        case SSHORT:
111            return 2;
112        case LONG:
113        case SLONG:
114        case FLOAT:
115            return 4;
116        case RATIONAL:
117        case SRATIONAL:
118        case DOUBLE:
119            return 8;
120        default:
121            return 0;
122    }
123}
124
125inline uint32_t calculateIfdSize(size_t numberOfEntries) {
126    return IFD_HEADER_SIZE + IFD_FOOTER_SIZE + TIFF_ENTRY_SIZE * numberOfEntries;
127}
128
129} /*namespace img_utils*/
130} /*namespace android*/
131
132#endif /*IMG_UTILS_TIFF_HELPERS_H*/
133