TiffEntry.h revision e507721000647a7d8afe44c63ef7fd04ef8971b1 
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_ENTRY
18#define IMG_UTILS_TIFF_ENTRY
19
20#include <img_utils/TiffWritable.h>
21#include <img_utils/TiffHelpers.h>
22#include <img_utils/EndianUtils.h>
23
24#include <cutils/compiler.h>
25#include <utils/String8.h>
26#include <utils/Errors.h>
27#include <stdint.h>
28
29namespace android {
30namespace img_utils {
31
32#define COMPARE_DEF(op) \
33inline bool operator op (const TiffEntry& entry) const;
34
35/**
36 * This class holds a single TIFF IFD entry.
37 */
38class ANDROID_API TiffEntry : public TiffWritable {
39    public:
40        // TODO: Copy constructor/equals here.
41        virtual ~TiffEntry();
42
43        /**
44         * Write the 12-byte IFD entry to the output. The given offset will be
45         * set as the tag value if the size of the tag value exceeds the max
46         * size for the TIFF Value field (4 bytes), and should be word aligned.
47         *
48         * Returns OK on success, or a negative error code on failure.
49         */
50        virtual status_t writeTagInfo(uint32_t offset, /*out*/EndianOutput* out) const = 0;
51
52        /**
53         * Get the count set for this entry. This corresponds to the TIFF Count
54         * field.
55         */
56        virtual uint32_t getCount() const = 0;
57
58        /**
59         * Get the tag id set for this entry. This corresponds to the TIFF Tag
60         * field.
61         */
62        virtual uint16_t getTag() const = 0;
63
64        /**
65         * Get the type set for this entry.  This corresponds to the TIFF Type
66         * field.
67         */
68        virtual TagType getType() const = 0;
69
70        /**
71         * Get the defined endianness for this entry.  If this is defined,
72         * the tag value will be written with the given byte order.
73         */
74        virtual Endianness getEndianness() const = 0;
75
76        /**
77         * Get the value for this entry.  This corresponds to the TIFF Value
78         * field.
79         *
80         * Returns NULL if the value is NULL, or if the type used does not
81         * match the type of this tag.
82         */
83        template<typename T>
84        const T* getData() const;
85
86        String8 toString() const;
87
88        /**
89         * Force the type used here to be a valid TIFF type.
90         *
91         * Returns NULL if the given value is NULL, or if the type given does
92         * not match the type of the value given.
93         */
94        template<typename T>
95        static const T* forceValidType(TagType type, const T* value);
96
97        virtual const void* getDataHelper() const = 0;
98
99        COMPARE_DEF(>)
100        COMPARE_DEF(<)
101
102        protected:
103            enum {
104                MAX_PRINT_STRING_LENGTH = 256
105            };
106};
107
108#define COMPARE(op) \
109bool TiffEntry::operator op (const TiffEntry& entry) const { \
110    return getComparableValue() op entry.getComparableValue(); \
111}
112
113COMPARE(>)
114COMPARE(<)
115
116
117template<typename T>
118const T* TiffEntry::getData() const {
119    const T* value = reinterpret_cast<const T*>(getDataHelper());
120    return forceValidType<T>(getType(), value);
121}
122
123#undef COMPARE
124#undef COMPARE_DEF
125
126} /*namespace img_utils*/
127} /*namespace android*/
128
129#endif /*IMG_UTILS_TIFF_ENTRY*/
130