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/*******************************************************************************
* Copyright (c) 2000, 2006 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.internal.image;
import org.eclipse.swt.*;
class PngIdatChunk extends PngChunk {
static final int HEADER_BYTES_LENGTH = 2;
static final int ADLER_FIELD_LENGTH = 4;
static final int HEADER_BYTE1_DATA_OFFSET = DATA_OFFSET + 0;
static final int HEADER_BYTE2_DATA_OFFSET = DATA_OFFSET + 1;
static final int ADLER_DATA_OFFSET = DATA_OFFSET + 2; // plus variable compressed data length
PngIdatChunk(byte headerByte1, byte headerByte2, byte[] data, int adler) {
super(data.length + HEADER_BYTES_LENGTH + ADLER_FIELD_LENGTH);
setType(TYPE_IDAT);
reference[HEADER_BYTE1_DATA_OFFSET] = headerByte1;
reference[HEADER_BYTE2_DATA_OFFSET] = headerByte2;
System.arraycopy(data, 0, reference, DATA_OFFSET, data.length);
setInt32(ADLER_DATA_OFFSET, adler);
setCRC(computeCRC());
}
PngIdatChunk(byte[] reference) {
super(reference);
}
int getChunkType() {
return CHUNK_IDAT;
}
/**
* Answer whether the chunk is a valid IDAT chunk.
*/
void validate(PngFileReadState readState, PngIhdrChunk headerChunk) {
if (!readState.readIHDR
|| (headerChunk.getMustHavePalette() && !readState.readPLTE)
|| readState.readIEND)
{
SWT.error(SWT.ERROR_INVALID_IMAGE);
} else {
readState.readIDAT = true;
}
super.validate(readState, headerChunk);
}
byte getDataByteAtOffset(int offset) {
return reference[DATA_OFFSET + offset];
}
}
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