/*
* Copyright 2002-2013 Drew Noakes
*
* 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
*
* http://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:
*
* http://drewnoakes.com/code/exif/
* http://code.google.com/p/metadata-extractor/
*/
package com.drew.metadata.jfif;
import com.drew.imaging.jpeg.JpegSegmentMetadataReader;
import com.drew.imaging.jpeg.JpegSegmentType;
import com.drew.lang.ByteArrayReader;
import com.drew.lang.RandomAccessReader;
import com.drew.lang.annotations.NotNull;
import com.drew.metadata.Metadata;
import java.io.IOException;
import java.util.Arrays;
/**
* Reader for JFIF data, found in the APP0 JPEG segment.
* <p/>
* More info at: http://en.wikipedia.org/wiki/JPEG_File_Interchange_Format
*
* @author Yuri Binev, Drew Noakes, Markus Meyer
*/
public class JfifReader implements JpegSegmentMetadataReader
{
@NotNull
public Iterable<JpegSegmentType> getSegmentTypes()
{
return Arrays.asList(JpegSegmentType.APP0);
}
public boolean canProcess(@NotNull byte[] segmentBytes, @NotNull JpegSegmentType segmentType)
{
return segmentBytes.length > 3 && "JFIF".equals(new String(segmentBytes, 0, 4));
}
public void extract(@NotNull byte[] segmentBytes, @NotNull Metadata metadata, @NotNull JpegSegmentType segmentType)
{
extract(new ByteArrayReader(segmentBytes), metadata);
}
/**
* Performs the Jfif data extraction, adding found values to the specified
* instance of {@link Metadata}.
*/
public void extract(@NotNull final RandomAccessReader reader, @NotNull final Metadata metadata)
{
JfifDirectory directory = metadata.getOrCreateDirectory(JfifDirectory.class);
try {
// For JFIF, the tag number is also the offset into the segment
int ver = reader.getUInt16(JfifDirectory.TAG_VERSION);
directory.setInt(JfifDirectory.TAG_VERSION, ver);
int units = reader.getUInt8(JfifDirectory.TAG_UNITS);
directory.setInt(JfifDirectory.TAG_UNITS, units);
int height = reader.getUInt16(JfifDirectory.TAG_RESX);
directory.setInt(JfifDirectory.TAG_RESX, height);
int width = reader.getUInt16(JfifDirectory.TAG_RESY);
directory.setInt(JfifDirectory.TAG_RESY, width);
} catch (IOException me) {
directory.addError(me.getMessage());
}
}
}