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      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 
     17 package com.android.gallery3d.exif;
     18 
     19 import android.util.Log;
     20 
     21 import java.io.IOException;
     22 import java.io.InputStream;
     23 
     24 /**
     25  * This class reads the EXIF header of a JPEG file and stores it in
     26  * {@link ExifData}.
     27  */
     28 class 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