1/*
2 * Copyright (C) 2012 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
17package com.android.gallery3d.exif;
18
19import android.util.Log;
20
21import java.io.IOException;
22import java.io.InputStream;
23
24/**
25 * This class reads the EXIF header of a JPEG file and stores it in
26 * {@link ExifData}.
27 */
28class ExifReader {
29    private static final String TAG = "ExifReader";
30
31    private final ExifInterface mInterface;
32
33    ExifReader(ExifInterface iRef) {
34        mInterface = iRef;
35    }
36
37    /**
38     * Parses the inputStream and and returns the EXIF data in an
39     * {@link ExifData}.
40     *
41     * @throws ExifInvalidFormatException
42     * @throws IOException
43     */
44    protected ExifData read(InputStream inputStream) throws ExifInvalidFormatException,
45            IOException {
46        ExifParser parser = ExifParser.parse(inputStream, mInterface);
47        ExifData exifData = new ExifData(parser.getByteOrder());
48        ExifTag tag = null;
49
50        int event = parser.next();
51        while (event != ExifParser.EVENT_END) {
52            switch (event) {
53                case ExifParser.EVENT_START_OF_IFD:
54                    exifData.addIfdData(new IfdData(parser.getCurrentIfd()));
55                    break;
56                case ExifParser.EVENT_NEW_TAG:
57                    tag = parser.getTag();
58                    if (!tag.hasValue()) {
59                        parser.registerForTagValue(tag);
60                    } else {
61                        exifData.getIfdData(tag.getIfd()).setTag(tag);
62                    }
63                    break;
64                case ExifParser.EVENT_VALUE_OF_REGISTERED_TAG:
65                    tag = parser.getTag();
66                    if (tag.getDataType() == ExifTag.TYPE_UNDEFINED) {
67                        parser.readFullTagValue(tag);
68                    }
69                    exifData.getIfdData(tag.getIfd()).setTag(tag);
70                    break;
71                case ExifParser.EVENT_COMPRESSED_IMAGE:
72                    byte buf[] = new byte[parser.getCompressedImageSize()];
73                    if (buf.length == parser.read(buf)) {
74                        exifData.setCompressedThumbnail(buf);
75                    } else {
76                        Log.w(TAG, "Failed to read the compressed thumbnail");
77                    }
78                    break;
79                case ExifParser.EVENT_UNCOMPRESSED_STRIP:
80                    buf = new byte[parser.getStripSize()];
81                    if (buf.length == parser.read(buf)) {
82                        exifData.setStripBytes(parser.getStripIndex(), buf);
83                    } else {
84                        Log.w(TAG, "Failed to read the strip bytes");
85                    }
86                    break;
87            }
88            event = parser.next();
89        }
90        return exifData;
91    }
92}
93