| /* |
| * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package com.sun.imageio.plugins.common; |
| |
| import java.io.IOException; |
| import javax.imageio.stream.ImageOutputStream; |
| |
| /* |
| * Came from GIFEncoder initially. |
| * Modified - to allow for output compressed data without the block counts |
| * which breakup the compressed data stream for GIF. |
| */ |
| public class BitFile { |
| ImageOutputStream output; |
| byte buffer[]; |
| int index; |
| int bitsLeft; // bits left at current index that are avail. |
| |
| /** note this also indicates gif format BITFile. **/ |
| boolean blocks = false; |
| |
| /* |
| * @param output destination for output data |
| * @param blocks GIF LZW requires block counts for output data |
| */ |
| public BitFile(ImageOutputStream output, boolean blocks) { |
| this.output = output; |
| this.blocks = blocks; |
| buffer = new byte[256]; |
| index = 0; |
| bitsLeft = 8; |
| } |
| |
| public void flush() throws IOException { |
| int numBytes = index + (bitsLeft == 8 ? 0 : 1); |
| if (numBytes > 0) { |
| if (blocks) { |
| output.write(numBytes); |
| } |
| output.write(buffer, 0, numBytes); |
| buffer[0] = 0; |
| index = 0; |
| bitsLeft = 8; |
| } |
| } |
| |
| public void writeBits(int bits, int numbits) throws IOException { |
| int bitsWritten = 0; |
| int numBytes = 255; // gif block count |
| do { |
| // This handles the GIF block count stuff |
| if ((index == 254 && bitsLeft == 0) || index > 254) { |
| if (blocks) { |
| output.write(numBytes); |
| } |
| |
| output.write(buffer, 0, numBytes); |
| |
| buffer[0] = 0; |
| index = 0; |
| bitsLeft = 8; |
| } |
| |
| if (numbits <= bitsLeft) { // bits contents fit in current index byte |
| if (blocks) { // GIF |
| buffer[index] |= (bits & ((1 << numbits) - 1)) << (8 - bitsLeft); |
| bitsWritten += numbits; |
| bitsLeft -= numbits; |
| numbits = 0; |
| } else { |
| buffer[index] |= (bits & ((1 << numbits) - 1)) << (bitsLeft - numbits); |
| bitsWritten += numbits; |
| bitsLeft -= numbits; |
| numbits = 0; |
| } |
| } else { // bits overflow from current byte to next. |
| if (blocks) { // GIF |
| // if bits > space left in current byte then the lowest order bits |
| // of code are taken and put in current byte and rest put in next. |
| buffer[index] |= (bits & ((1 << bitsLeft) - 1)) << (8 - bitsLeft); |
| bitsWritten += bitsLeft; |
| bits >>= bitsLeft; |
| numbits -= bitsLeft; |
| buffer[++index] = 0; |
| bitsLeft = 8; |
| } else { |
| // if bits > space left in current byte then the highest order bits |
| // of code are taken and put in current byte and rest put in next. |
| // at highest order bit location !! |
| int topbits = (bits >>> (numbits - bitsLeft)) & ((1 << bitsLeft) - 1); |
| buffer[index] |= topbits; |
| numbits -= bitsLeft; // ok this many bits gone off the top |
| bitsWritten += bitsLeft; |
| buffer[++index] = 0; // next index |
| bitsLeft = 8; |
| } |
| } |
| } while (numbits != 0); |
| } |
| } |