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| 1 | /* | ||
| 2 | * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package com.sun.imageio.plugins.common; | ||
| 27 | |||
| 28 | import java.io.IOException; | ||
| 29 | import javax.imageio.stream.ImageOutputStream; | ||
| 30 | |||
| 31 | /* | ||
| 32 | * Came from GIFEncoder initially. | ||
| 33 | * Modified - to allow for output compressed data without the block counts | ||
| 34 | * which breakup the compressed data stream for GIF. | ||
| 35 | */ | ||
| 36 | public class BitFile { | ||
| 37 | ImageOutputStream output; | ||
| 38 | byte buffer[]; | ||
| 39 | int index; | ||
| 40 | int bitsLeft; // bits left at current index that are avail. | ||
| 41 | |||
| 42 | /** note this also indicates gif format BITFile. **/ | ||
| 43 | boolean blocks = false; | ||
| 44 | |||
| 45 | /* | ||
| 46 | * @param output destination for output data | ||
| 47 | * @param blocks GIF LZW requires block counts for output data | ||
| 48 | */ | ||
| 49 | public BitFile(ImageOutputStream output, boolean blocks) { | ||
| 50 | this.output = output; | ||
| 51 | this.blocks = blocks; | ||
| 52 | buffer = new byte[256]; | ||
| 53 | index = 0; | ||
| 54 | bitsLeft = 8; | ||
| 55 | } | ||
| 56 | |||
| 57 | public void flush() throws IOException { | ||
| 58 | int numBytes = index + (bitsLeft == 8 ? 0 : 1); | ||
| 59 | if (numBytes > 0) { | ||
| 60 | if (blocks) { | ||
| 61 | output.write(numBytes); | ||
| 62 | } | ||
| 63 | output.write(buffer, 0, numBytes); | ||
| 64 | buffer[0] = 0; | ||
| 65 | index = 0; | ||
| 66 | bitsLeft = 8; | ||
| 67 | } | ||
| 68 | } | ||
| 69 | |||
| 70 | public void writeBits(int bits, int numbits) throws IOException { | ||
| 71 | int bitsWritten = 0; | ||
| 72 | int numBytes = 255; // gif block count | ||
| 73 | do { | ||
| 74 | // This handles the GIF block count stuff | ||
| 75 | if ((index == 254 && bitsLeft == 0) || index > 254) { | ||
| 76 | if (blocks) { | ||
| 77 | output.write(numBytes); | ||
| 78 | } | ||
| 79 | |||
| 80 | output.write(buffer, 0, numBytes); | ||
| 81 | |||
| 82 | buffer[0] = 0; | ||
| 83 | index = 0; | ||
| 84 | bitsLeft = 8; | ||
| 85 | } | ||
| 86 | |||
| 87 | if (numbits <= bitsLeft) { // bits contents fit in current index byte | ||
| 88 | if (blocks) { // GIF | ||
| 89 | buffer[index] |= (bits & ((1 << numbits) - 1)) << (8 - bitsLeft); | ||
| 90 | bitsWritten += numbits; | ||
| 91 | bitsLeft -= numbits; | ||
| 92 | numbits = 0; | ||
| 93 | } else { | ||
| 94 | buffer[index] |= (bits & ((1 << numbits) - 1)) << (bitsLeft - numbits); | ||
| 95 | bitsWritten += numbits; | ||
| 96 | bitsLeft -= numbits; | ||
| 97 | numbits = 0; | ||
| 98 | } | ||
| 99 | } else { // bits overflow from current byte to next. | ||
| 100 | if (blocks) { // GIF | ||
| 101 | // if bits > space left in current byte then the lowest order bits | ||
| 102 | // of code are taken and put in current byte and rest put in next. | ||
| 103 | buffer[index] |= (bits & ((1 << bitsLeft) - 1)) << (8 - bitsLeft); | ||
| 104 | bitsWritten += bitsLeft; | ||
| 105 | bits >>= bitsLeft; | ||
| 106 | numbits -= bitsLeft; | ||
| 107 | buffer[++index] = 0; | ||
| 108 | bitsLeft = 8; | ||
| 109 | } else { | ||
| 110 | // if bits > space left in current byte then the highest order bits | ||
| 111 | // of code are taken and put in current byte and rest put in next. | ||
| 112 | // at highest order bit location !! | ||
| 113 | int topbits = (bits >>> (numbits - bitsLeft)) & ((1 << bitsLeft) - 1); | ||
| 114 | buffer[index] |= topbits; | ||
| 115 | numbits -= bitsLeft; // ok this many bits gone off the top | ||
| 116 | bitsWritten += bitsLeft; | ||
| 117 | buffer[++index] = 0; // next index | ||
| 118 | bitsLeft = 8; | ||
| 119 | } | ||
| 120 | } | ||
| 121 | } while (numbits != 0); | ||
| 122 | } | ||
| 123 | } | ||