/*
* 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.
* under the License.
*/
package org.apache.sanselan.formats.jpeg.segments;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import org.apache.sanselan.ImageReadException;
public class DQTSegment extends Segment
{
public final ArrayList quantizationTables = new ArrayList();
public static class QuantizationTable
{
public final int precision;
public final int destinationIdentifier;
public final int[] elements;
public QuantizationTable(int precision, int destinationIdentifier,
int[] elements)
{
this.precision = precision;
this.destinationIdentifier = destinationIdentifier;
this.elements = elements;
}
}
public DQTSegment(int marker, byte[] segmentData)
throws ImageReadException, IOException
{
this(marker, segmentData.length, new ByteArrayInputStream(segmentData));
}
public DQTSegment(int marker, int length, InputStream is)
throws ImageReadException, IOException
{
super(marker, length);
while (length > 0)
{
int precisionAndDestination = readByte(
"QuantizationTablePrecisionAndDestination", is,
"Not a Valid JPEG File");
length--;
int precision = (precisionAndDestination >> 4) & 0xf;
int destinationIdentifier = precisionAndDestination & 0xf;
int[] elements = new int[64];
for (int i = 0; i < 64; i++)
{
if (precision == 0)
{
elements[i] = 0xff & readByte("QuantizationTableElement",
is, "Not a Valid JPEG File");
length--;
}
else if (precision == 1)
{
elements[i] = read2Bytes("QuantizationTableElement",
is, "Not a Valid JPEG File");
length -= 2;
}
else
{
throw new ImageReadException("Quantization table precision '" +
precision + "' is invalid");
}
}
quantizationTables.add(new QuantizationTable(
precision, destinationIdentifier, elements));
}
}
public String getDescription()
{
return "DQT (" + getSegmentType() + ")";
}
}