content: /*
   * Copyright 2002-2019 Drew Noakes and contributors
   *
   *    Licensed under the Apache License, Version 2.0 (the "License");
   *    you may not use this file except in compliance with the License.
   *    You may obtain a copy of the License at
   *
   *        https://www.apache.org/licenses/LICENSE-2.0
   *
   *    Unless required by applicable law or agreed to in writing, software
   *    distributed under the License is distributed on an "AS IS" BASIS,
   *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *    See the License for the specific language governing permissions and
   *    limitations under the License.
   *
   * More information about this project is available at:
   *
   *    https://drewnoakes.com/code/exif/
   *    https://github.com/drewnoakes/metadata-extractor
   */
  package com.drew.metadata.jpeg;
  
  import com.drew.imaging.jpeg.JpegSegmentMetadataReader;
  import com.drew.imaging.jpeg.JpegSegmentType;
  import com.drew.lang.SequentialByteArrayReader;
  import com.drew.lang.SequentialReader;
  import com.drew.lang.annotations.NotNull;
  import com.drew.metadata.ErrorDirectory;
  import com.drew.metadata.Metadata;
  
  import java.io.IOException;
  import java.util.Collections;
  
  /**
   * Decodes JPEG DNL data, adjusting the image height with information missing from the JPEG SOFx segment.
   *
   * @author Nadahar
   */
  public class JpegDnlReader implements JpegSegmentMetadataReader
  {
      @NotNull
      public Iterable<JpegSegmentType> getSegmentTypes()
      {
          return Collections.singletonList(JpegSegmentType.DNL);
      }
  
      public void readJpegSegments(@NotNull Iterable<byte[]> segments, @NotNull Metadata metadata, @NotNull JpegSegmentType segmentType)
      {
          for (byte[] segmentBytes : segments) {
              extract(segmentBytes, metadata, segmentType);
          }
      }
  
      public void extract(byte[] segmentBytes, Metadata metadata, JpegSegmentType segmentType)
      {
          JpegDirectory directory = metadata.getFirstDirectoryOfType(JpegDirectory.class);
          if (directory == null) {
              ErrorDirectory errorDirectory = new ErrorDirectory();
              metadata.addDirectory(errorDirectory);
              errorDirectory.addError("DNL segment found without SOFx - illegal JPEG format");
              return;
          }
  
          SequentialReader reader = new SequentialByteArrayReader(segmentBytes);
  
          try {
              // Only set height from DNL if it's not already defined
              Integer i = directory.getInteger(JpegDirectory.TAG_IMAGE_HEIGHT);
              if (i == null || i == 0) {
                  directory.setInt(JpegDirectory.TAG_IMAGE_HEIGHT, reader.getUInt16());
              }
          } catch (IOException ex) {
              directory.addError(ex.getMessage());
          }
      }
  }
  