/*
* This is public domain software - that is, you can do whatever you want
* with it, and include it software that is licensed under the GNU or the
* BSD license, or whatever other licence you choose, including proprietary
* closed source licenses. I do ask that you leave this header in tact.
*
* If you make modifications to this code that you think would benefit the
* wider community, please send me a copy and I'll post it on my site.
*
* If you make use of this code, I'd appreciate hearing about it.
* metadata_extractor [at] drewnoakes [dot] com
* Latest version of this software kept at
* http://drewnoakes.com/
*/
package com.drew.imaging.jpeg;
import java.io.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
/**
* Holds a collection of Jpeg data segments. This need not necessarily be all segments
* within the Jpeg. For example, it may be convenient to store only the non-image
* segments when analysing (or serializing) metadata.
*
* Segments are keyed via their segment marker (a byte). Where multiple segments use the
* same segment marker, they will all be stored and available.
*/
public class JpegSegmentData implements Serializable
{
static final long serialVersionUID = 7110175216435025451L;
/** A map of byte[], keyed by the segment marker */
private final HashMap _segmentDataMap;
/**
* Creates a new JpegSegmentData collection object.
*/
public JpegSegmentData()
{
_segmentDataMap = new HashMap(10);
}
/**
* Adds segment bytes to the collection.
* @param segmentMarker
* @param segmentBytes
*/
public void addSegment(byte segmentMarker, byte[] segmentBytes)
{
final List segmentList = getOrCreateSegmentList(segmentMarker);
segmentList.add(segmentBytes);
}
/**
* Gets the first Jpeg segment data for the specified marker.
* @param segmentMarker the byte identifier for the desired segment
* @return a byte[] containing segment data or null if no data exists for that segment
*/
public byte[] getSegment(byte segmentMarker)
{
return getSegment(segmentMarker, 0);
}
/**
* Gets segment data for a specific occurrence and marker. Use this method when more than one occurrence
* of segment data for a given marker exists.
* @param segmentMarker identifies the required segment
* @param occurrence the zero-based index of the occurrence
* @return the segment data as a byte[], or null if no segment exists for the marker & occurrence
*/
public byte[] getSegment(byte segmentMarker, int occurrence)
{
final List segmentList = getSegmentList(segmentMarker);
if (segmentList==null || segmentList.size()<=occurrence)
return null;
else
return (byte[]) segmentList.get(occurrence);
}
/**
* Returns the count of segment data byte arrays stored for a given segment marker.
* @param segmentMarker identifies the required segment
* @return the segment count (zero if no segments exist).
*/
public int getSegmentCount(byte segmentMarker)
{
final List segmentList = getSegmentList(segmentMarker);
if (segmentList==null)
return 0;
else
return segmentList.size();
}
/**
* Removes a specified instance of a segment's data from the collection. Use this method when more than one
* occurrence of segment data for a given marker exists.
* @param segmentMarker identifies the required segment
* @param occurrence the zero-based index of the segment occurrence to remove.
*/
public void removeSegmentOccurrence(byte segmentMarker, int occurrence)
{
final List segmentList = (List)_segmentDataMap.get(new Byte(segmentMarker));
segmentList.remove(occurrence);
}
/**
* Removes all segments from the collection having the specified marker.
* @param segmentMarker identifies the required segment
*/
public void removeSegment(byte segmentMarker)
{
_segmentDataMap.remove(new Byte(segmentMarker));
}
/**
* Determines whether data is present for a given segment marker.
* @param segmentMarker identifies the required segment
* @return true if data exists, otherwise false
*/
public boolean containsSegment(byte segmentMarker)
{
return _segmentDataMap.containsKey(new Byte(segmentMarker));
}
/**
* Serialises the contents of a JpegSegmentData to a file.
* @param file to file to write from
* @param segmentData the data to write
* @throws IOException if problems occur while writing
*/
public static void ToFile(File file, JpegSegmentData segmentData) throws IOException
{
ObjectOutputStream outputStream = null;
try
{
outputStream = new ObjectOutputStream(new FileOutputStream(file));
outputStream.writeObject(segmentData);
}
finally
{
if (outputStream!=null)
outputStream.close();
}
}
/**
* Deserialises the contents of a JpegSegmentData from a file.
* @param file the file to read from
* @return the JpegSegmentData as read
* @throws IOException if problems occur while reading
* @throws ClassNotFoundException if problems occur while deserialising
*/
public static JpegSegmentData FromFile(File file) throws IOException, ClassNotFoundException
{
ObjectInputStream inputStream = null;
try
{
inputStream = new ObjectInputStream(new FileInputStream(file));
return (JpegSegmentData)inputStream.readObject();
}
finally
{
if (inputStream!=null)
inputStream.close();
}
}
private List getSegmentList(byte segmentMarker)
{
return (List)_segmentDataMap.get(new Byte(segmentMarker));
}
private List getOrCreateSegmentList(byte segmentMarker)
{
List segmentList;
Byte key = new Byte(segmentMarker);
if (_segmentDataMap.containsKey(key)) {
segmentList = (List)_segmentDataMap.get(key);
} else {
segmentList = new ArrayList();
_segmentDataMap.put(key, segmentList);
}
return segmentList;
}
}