Mercurial > projects > dwt-linux
view dwt/internal/image/TIFFRandomFileAccess.d @ 13:3d9bbe0a83a0
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author | Frank Benoit <benoit@tionex.de> |
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date | Sun, 06 Jan 2008 22:54:14 +0100 |
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children | fc2b263b8a3f |
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/******************************************************************************* * Copyright (c) 2000, 2003 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.TIFFRandomFileAccess; import dwt.internal.image.LEDataInputStream; import Math = tango.math.Math; import tango.core.Exception; final class TIFFRandomFileAccess { LEDataInputStream inputStream; int start, current, next; byte[][] buffers; static final int CHUNK_SIZE = 8192; static final int LIST_SIZE = 128; public this(LEDataInputStream stream) { inputStream = stream; start = current = next = inputStream.getPosition(); buffers = new byte[][](LIST_SIZE); } void seek(int pos) { if (pos == current) return; if (pos < start) throw new IOException( "pos < start" ); current = pos; if (current > next) { int n = current - next; /* store required bytes */ int index = next / CHUNK_SIZE; int offset = next % CHUNK_SIZE; while (n > 0) { if (index >= buffers.length) { byte[][] oldBuffers = buffers; buffers = new byte[][]( Math.max(index + 1, oldBuffers.length + LIST_SIZE) ); buffers[ 0 .. oldBuffers.length ] = oldBuffers[]; } if (buffers[index] == null) buffers[index] = new byte[CHUNK_SIZE]; int cnt = inputStream.read(buffers[index], offset, Math.min(n, CHUNK_SIZE - offset)); n -= cnt; next += cnt; index++; offset = 0; } } } void read(byte b[]) { int size = b.length; int nCached = Math.min(size, next - current); int nMissing = size - next + current; int destNext = 0; if (nCached > 0) { /* Get cached bytes */ int index = current / CHUNK_SIZE; int offset = current % CHUNK_SIZE; while (nCached > 0) { int cnt = Math.min(nCached, CHUNK_SIZE - offset); b[ destNext .. destNext+cnt ] = buffers[index][ offset .. offset+cnt ]; nCached -= cnt; destNext += cnt; index++; offset = 0; } } if (nMissing > 0) { /* Read required bytes */ int index = next / CHUNK_SIZE; int offset = next % CHUNK_SIZE; while (nMissing > 0) { if (index >= buffers.length) { byte[][] oldBuffers = buffers; buffers = new byte[][](Math.max(index, oldBuffers.length + LIST_SIZE)); buffers[ 0 .. oldBuffers.length ] = oldBuffers[]; } if (buffers[index] == null) buffers[index] = new byte[CHUNK_SIZE]; int cnt = inputStream.read(buffers[index], offset, Math.min(nMissing, CHUNK_SIZE - offset)); b[ destNext .. destNext+cnt ] = buffers[index][ offset .. offset+cnt ]; nMissing -= cnt; next += cnt; destNext += cnt; index++; offset = 0; } } current += size; } }