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view dwt/internal/image/JPEGScanHeader.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, 2005 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; final class JPEGScanHeader : JPEGVariableSizeSegment { public int[][] componentParameters; public JPEGScanHeader(byte[] reference) { super(reference); } public JPEGScanHeader(LEDataInputStream byteStream) { super(byteStream); initializeComponentParameters(); } public int getApproxBitPositionHigh() { return reference[(2 * getNumberOfImageComponents()) + 7] >> 4; } public int getApproxBitPositionLow() { return reference[(2 * getNumberOfImageComponents()) + 7] & 0xF; } public int getEndOfSpectralSelection() { return reference[(2 * getNumberOfImageComponents()) + 6]; } public int getNumberOfImageComponents() { return reference[4]; } public int getStartOfSpectralSelection() { return reference[(2 * getNumberOfImageComponents()) + 5]; } /* Used when decoding. */ void initializeComponentParameters() { int compCount = getNumberOfImageComponents(); componentParameters = new int[0][]; for (int i = 0; i < compCount; i++) { int ofs = 5 + i * 2; int cid = reference[ofs] & 0xFF; int dc = (reference[ofs + 1] & 0xFF) >> 4; int ac = reference[ofs + 1] & 0xF; if (componentParameters.length <= cid) { int[][] newParams = new int[cid + 1][]; System.arraycopy(componentParameters, 0, newParams, 0, componentParameters.length); componentParameters = newParams; } componentParameters[cid] = new int[] { dc, ac }; } } /* Used when encoding. */ public void initializeContents() { int compCount = getNumberOfImageComponents(); int[][] compSpecParams = componentParameters; if (compCount is 0 || compCount !is compSpecParams.length) { DWT.error(DWT.ERROR_INVALID_IMAGE); } for (int i = 0; i < compCount; i++) { int ofs = i * 2 + 5; int[] compParams = compSpecParams[i]; reference[ofs] = (byte)(i + 1); reference[ofs + 1] = (byte)(compParams[0] * 16 + compParams[1]); } } public void setEndOfSpectralSelection(int anInteger) { reference[(2 * getNumberOfImageComponents()) + 6] = (byte)anInteger; } public void setNumberOfImageComponents(int anInteger) { reference[4] = (byte)(anInteger & 0xFF); } public void setStartOfSpectralSelection(int anInteger) { reference[(2 * getNumberOfImageComponents()) + 5] = (byte)anInteger; } public int signature() { return JPEGFileFormat.SOS; } public bool verifyProgressiveScan() { int start = getStartOfSpectralSelection(); int end = getEndOfSpectralSelection(); int low = getApproxBitPositionLow(); int high = getApproxBitPositionHigh(); int count = getNumberOfImageComponents(); if ((start is 0 && end is 00) || (start <= end && end <= 63)) { if (low <= 13 && high <= 13 && (high is 0 || high is low + 1)) { return start is 0 || (start > 0 && count is 1); } } return false; } public bool isACProgressiveScan() { return getStartOfSpectralSelection() !is 0 && getEndOfSpectralSelection() !is 0; } public bool isDCProgressiveScan() { return getStartOfSpectralSelection() is 0 && getEndOfSpectralSelection() is 0; } public bool isFirstScan() { return getApproxBitPositionHigh() is 0; } }