Mercurial > projects > dwt-win
diff dwt/internal/image/PngIdatChunk.d @ 2:57151e2793a2
More common modules from dwt-linux
author | Frank Benoit <benoit@tionex.de> |
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date | Wed, 23 Jan 2008 12:01:46 +0100 |
parents | |
children | 92c102dd64a3 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/dwt/internal/image/PngIdatChunk.d Wed Jan 23 12:01:46 2008 +0100 @@ -0,0 +1,67 @@ +/******************************************************************************* + * 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 + * Port to the D programming language: + * Frank Benoit <benoit@tionex.de> + *******************************************************************************/ +module dwt.internal.image.PngIdatChunk; + + +import dwt.DWT; +import dwt.internal.image.PngFileReadState; +import dwt.internal.image.PngIhdrChunk; +import dwt.internal.image.PngChunk; + +class PngIdatChunk : PngChunk { + + static const int HEADER_BYTES_LENGTH = 2; + static const int ADLER_FIELD_LENGTH = 4; + static const int HEADER_BYTE1_DATA_OFFSET = DATA_OFFSET + 0; + static const int HEADER_BYTE2_DATA_OFFSET = DATA_OFFSET + 1; + static const int ADLER_DATA_OFFSET = DATA_OFFSET + 2; // plus variable compressed data length + +this(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()); +} + +this(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]; +} + +}