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view dwt/internal/image/PngIdatChunk.d @ 0:380af2bdd8e5
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author | Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com> |
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date | Sat, 09 Aug 2008 17:00:02 +0200 |
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children | 1a8b3cb347e0 |
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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 *******************************************************************************/ module dwt.internal.image; import dwt.DWT; class PngIdatChunk : 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) { DWT.error(DWT.ERROR_INVALID_IMAGE); } else { readState.readIDAT = true; } super.validate(readState, headerChunk); } byte getDataByteAtOffset(int offset) { return reference[DATA_OFFSET + offset]; } }