| /******************************************************************************* |
| * 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 |
| *******************************************************************************/ |
| package org.eclipse.swt.internal.image; |
| |
| import java.io.*; |
| |
| final class TIFFRandomFileAccess { |
| |
| LEDataInputStream inputStream; |
| int start, current, next; |
| byte[][] buffers; |
| |
| static final int CHUNK_SIZE = 8192; |
| static final int LIST_SIZE = 128; |
| |
| public TIFFRandomFileAccess(LEDataInputStream stream) { |
| inputStream = stream; |
| start = current = next = inputStream.getPosition(); |
| buffers = new byte[LIST_SIZE][]; |
| } |
| |
| void seek(int pos) throws IOException { |
| if (pos == current) return; |
| if (pos < start) throw new IOException(); |
| 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)][]; |
| System.arraycopy(oldBuffers, 0, buffers, 0, oldBuffers.length); |
| } |
| 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[]) throws IOException { |
| 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); |
| System.arraycopy(buffers[index], offset, b, destNext, 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)][]; |
| System.arraycopy(oldBuffers, 0, buffers, 0, oldBuffers.length); |
| } |
| if (buffers[index] == null) buffers[index] = new byte[CHUNK_SIZE]; |
| int cnt = inputStream.read(buffers[index], offset, Math.min(nMissing, CHUNK_SIZE - offset)); |
| System.arraycopy(buffers[index], offset, b, destNext, cnt); |
| nMissing -= cnt; |
| next += cnt; |
| destNext += cnt; |
| index++; |
| offset = 0; |
| } |
| } |
| current += size; |
| } |
| |
| } |