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.Metadata;
  
  import java.io.IOException;
  import java.util.Arrays;
  
  /**
   * Decodes JPEG SOFn data, populating a {@link Metadata} object with tag values in a {@link JpegDirectory}.
   *
   * @author Drew Noakes https://drewnoakes.com
   * @author Darrell Silver https://www.darrellsilver.com
   */
  public class JpegReader implements JpegSegmentMetadataReader
  {
      @NotNull
      public Iterable<JpegSegmentType> getSegmentTypes()
      {
          // NOTE that some SOFn values do not exist
          return Arrays.asList(
              JpegSegmentType.SOF0,
              JpegSegmentType.SOF1,
              JpegSegmentType.SOF2,
              JpegSegmentType.SOF3,
  //            JpegSegmentType.SOF4,
              JpegSegmentType.SOF5,
              JpegSegmentType.SOF6,
              JpegSegmentType.SOF7,
  //            JpegSegmentType.JPG,
              JpegSegmentType.SOF9,
              JpegSegmentType.SOF10,
              JpegSegmentType.SOF11,
  //            JpegSegmentType.SOF12,
              JpegSegmentType.SOF13,
              JpegSegmentType.SOF14,
              JpegSegmentType.SOF15
          );
      }
  
      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 = new JpegDirectory();
          metadata.addDirectory(directory);
  
          // The value of TAG_COMPRESSION_TYPE is determined by the segment type found
          directory.setInt(JpegDirectory.TAG_COMPRESSION_TYPE, segmentType.byteValue - JpegSegmentType.SOF0.byteValue);
  
          final int JPEG_HEADER_SIZE = 1 + 2 + 2 + 1;
  
          if (segmentBytes.length < JPEG_HEADER_SIZE) {
              directory.addError("Insufficient bytes for JPEG segment header.");
              return;
          }
  
          SequentialReader reader = new SequentialByteArrayReader(segmentBytes);
  
          try {
              directory.setInt(JpegDirectory.TAG_DATA_PRECISION, reader.getUInt8());
              directory.setInt(JpegDirectory.TAG_IMAGE_HEIGHT, reader.getUInt16());
              directory.setInt(JpegDirectory.TAG_IMAGE_WIDTH, reader.getUInt16());
              short componentCount = reader.getUInt8();
              directory.setInt(JpegDirectory.TAG_NUMBER_OF_COMPONENTS, componentCount);
  
              final int JPEG_COMPONENT_SIZE = 1 + 1 + 1;
  
              if (reader.available() < componentCount * JPEG_COMPONENT_SIZE) {
                  directory.addError("Insufficient bytes for JPEG the requested number of JPEG components.");
                  return;
              }
  
              // for each component, there are three bytes of data:
              // 1 - Component ID: 1 = Y, 2 = Cb, 3 = Cr, 4 = I, 5 = Q
              // 2 - Sampling factors: bit 0-3 vertical, 4-7 horizontal
              // 3 - Quantization table number
              for (int i = 0; i < (int)componentCount; i++) {
                  final int componentId = reader.getUInt8();
                  final int samplingFactorByte = reader.getUInt8();
                  final int quantizationTableNumber = reader.getUInt8();
                  final JpegComponent component = new JpegComponent(componentId, samplingFactorByte, quantizationTableNumber);
                  directory.setObject(JpegDirectory.TAG_COMPONENT_DATA_1 + i, component);
              }
          } catch (IOException ex) {
              directory.addError(ex.getMessage());
          }
      }
  }
  