From 346f3a9817b1e0812565396b9811a1ce5adc97b8 Mon Sep 17 00:00:00 2001 From: jules Date: Fri, 13 Dec 2013 15:28:31 -0500 Subject: reorganize --- js/vendor/gif-encode/LZWEncoder.js | 328 +++++++++++++++++++++++++++++++++++++ 1 file changed, 328 insertions(+) create mode 100644 js/vendor/gif-encode/LZWEncoder.js (limited to 'js/vendor/gif-encode/LZWEncoder.js') diff --git a/js/vendor/gif-encode/LZWEncoder.js b/js/vendor/gif-encode/LZWEncoder.js new file mode 100644 index 0000000..e3c512a --- /dev/null +++ b/js/vendor/gif-encode/LZWEncoder.js @@ -0,0 +1,328 @@ +/** +* This class handles LZW encoding +* Adapted from Jef Poskanzer's Java port by way of J. M. G. Elliott. +* @author Kevin Weiner (original Java version - kweiner@fmsware.com) +* @author Thibault Imbert (AS3 version - bytearray.org) +* @version 0.1 AS3 implementation +*/ + +//import flash.utils.ByteArray; + +LZWEncoder = function() +{ + var exports = {}; + /*private_static*/ var EOF/*int*/ = -1; + /*private*/ var imgW/*int*/; + /*private*/ var imgH/*int*/ + /*private*/ var pixAry/*ByteArray*/; + /*private*/ var initCodeSize/*int*/; + /*private*/ var remaining/*int*/; + /*private*/ var curPixel/*int*/; + + // GIFCOMPR.C - GIF Image compression routines + // Lempel-Ziv compression based on 'compress'. GIF modifications by + // David Rowley (mgardi@watdcsu.waterloo.edu) + // General DEFINEs + + /*private_static*/ var BITS/*int*/ = 12; + /*private_static*/ var HSIZE/*int*/ = 5003; // 80% occupancy + + // GIF Image compression - modified 'compress' + // Based on: compress.c - File compression ala IEEE Computer, June 1984. + // By Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas) + // Jim McKie (decvax!mcvax!jim) + // Steve Davies (decvax!vax135!petsd!peora!srd) + // Ken Turkowski (decvax!decwrl!turtlevax!ken) + // James A. Woods (decvax!ihnp4!ames!jaw) + // Joe Orost (decvax!vax135!petsd!joe) + + /*private*/ var n_bits/*int*/ // number of bits/code + /*private*/ var maxbits/*int*/ = BITS; // user settable max # bits/code + /*private*/ var maxcode/*int*/ // maximum code, given n_bits + /*private*/ var maxmaxcode/*int*/ = 1 << BITS; // should NEVER generate this code + /*private*/ var htab/*Array*/ = new Array; + /*private*/ var codetab/*Array*/ = new Array; + /*private*/ var hsize/*int*/ = HSIZE; // for dynamic table sizing + /*private*/ var free_ent/*int*/ = 0; // first unused entry + + // block compression parameters -- after all codes are used up, + // and compression rate changes, start over. + + /*private*/ var clear_flg/*Boolean*/ = false; + + // Algorithm: use open addressing double hashing (no chaining) on the + // prefix code / next character combination. We do a variant of Knuth's + // algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime + // secondary probe. Here, the modular division first probe is gives way + // to a faster exclusive-or manipulation. Also do block compression with + // an adaptive reset, whereby the code table is cleared when the compression + // ratio decreases, but after the table fills. The variable-length output + // codes are re-sized at this point, and a special CLEAR code is generated + // for the decompressor. Late addition: construct the table according to + // file size for noticeable speed improvement on small files. Please direct + // questions about this implementation to ames!jaw. + + /*private*/ var g_init_bits/*int*/; + /*private*/ var ClearCode/*int*/; + /*private*/ var EOFCode/*int*/; + + // output + // Output the given code. + // Inputs: + // code: A n_bits-bit integer. If == -1, then EOF. This assumes + // that n_bits =< wordsize - 1. + // Outputs: + // Outputs code to the file. + // Assumptions: + // Chars are 8 bits long. + // Algorithm: + // Maintain a BITS character long buffer (so that 8 codes will + // fit in it exactly). Use the VAX insv instruction to insert each + // code in turn. When the buffer fills up empty it and start over. + + /*private*/ var cur_accum/*int*/ = 0; + /*private*/ var cur_bits/*int*/ = 0; + /*private*/ var masks/*Array*/ = [ 0x0000, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF ]; + + // Number of characters so far in this 'packet' + /*private*/ var a_count/*int*/; + + // Define the storage for the packet accumulator + /*private*/ var accum/*ByteArray*/ = []; + + var LZWEncoder = exports.LZWEncoder = function LZWEncoder (width/*int*/, height/*int*/, pixels/*ByteArray*/, color_depth/*int*/) + { + + imgW = width; + imgH = height; + pixAry = pixels; + initCodeSize = Math.max(2, color_depth); + + } + + // Add a character to the end of the current packet, and if it is 254 + // characters, flush the packet to disk. + var char_out = function char_out(c/*Number*/, outs/*ByteArray*/)/*void*/ + { + accum[a_count++] = c; + if (a_count >= 254) flush_char(outs); + + } + + // Clear out the hash table + // table clear for block compress + + var cl_block = function cl_block(outs/*ByteArray*/)/*void*/ + { + + cl_hash(hsize); + free_ent = ClearCode + 2; + clear_flg = true; + output(ClearCode, outs); + + } + + // reset code table + var cl_hash = function cl_hash(hsize/*int*/)/*void*/ + { + + for (var i/*int*/ = 0; i < hsize; ++i) htab[i] = -1; + + } + + var compress = exports.compress = function compress(init_bits/*int*/, outs/*ByteArray*/)/*void*/ + + { + var fcode/*int*/; + var i/*int*/ /* = 0 */; + var c/*int*/; + var ent/*int*/; + var disp/*int*/; + var hsize_reg/*int*/; + var hshift/*int*/; + + // Set up the globals: g_init_bits - initial number of bits + g_init_bits = init_bits; + + // Set up the necessary values + clear_flg = false; + n_bits = g_init_bits; + maxcode = MAXCODE(n_bits); + + ClearCode = 1 << (init_bits - 1); + EOFCode = ClearCode + 1; + free_ent = ClearCode + 2; + + a_count = 0; // clear packet + + ent = nextPixel(); + + hshift = 0; + for (fcode = hsize; fcode < 65536; fcode *= 2) + ++hshift; + hshift = 8 - hshift; // set hash code range bound + + hsize_reg = hsize; + cl_hash(hsize_reg); // clear hash table + + output(ClearCode, outs); + + outer_loop: while ((c = nextPixel()) != EOF) + + { + + fcode = (c << maxbits) + ent; + i = (c << hshift) ^ ent; // xor hashing + + if (htab[i] == fcode) + { + ent = codetab[i]; + continue; + } else if (htab[i] >= 0) // non-empty slot + { + disp = hsize_reg - i; // secondary hash (after G. Knott) + if (i == 0) + disp = 1; + do + { + + if ((i -= disp) < 0) i += hsize_reg; + + if (htab[i] == fcode) + { + ent = codetab[i]; + continue outer_loop; + } + } while (htab[i] >= 0); + } + + output(ent, outs); + ent = c; + if (free_ent < maxmaxcode) + { + codetab[i] = free_ent++; // code -> hashtable + htab[i] = fcode; + } else cl_block(outs); + } + + // Put out the final code. + output(ent, outs); + output(EOFCode, outs); + + } + + // ---------------------------------------------------------------------------- + var encode = exports.encode = function encode(os/*ByteArray*/)/*void*/ + { + os.writeByte(initCodeSize); // write "initial code size" byte + remaining = imgW * imgH; // reset navigation variables + curPixel = 0; + compress(initCodeSize + 1, os); // compress and write the pixel data + os.writeByte(0); // write block terminator + + } + + // Flush the packet to disk, and reset the accumulator + var flush_char = function flush_char(outs/*ByteArray*/)/*void*/ + { + + if (a_count > 0) + { + outs.writeByte(a_count); + outs.writeBytes(accum, 0, a_count); + a_count = 0; + } + + } + + var MAXCODE = function MAXCODE(n_bits/*int*/)/*int*/ + { + + return (1 << n_bits) - 1; + + } + + // ---------------------------------------------------------------------------- + // Return the next pixel from the image + // ---------------------------------------------------------------------------- + + var nextPixel = function nextPixel()/*int*/ + { + + if (remaining == 0) return EOF; + + --remaining; + + var pix/*Number*/ = pixAry[curPixel++]; + + return pix & 0xff; + + } + + var output = function output(code/*int*/, outs/*ByteArray*/)/*void*/ + + { + cur_accum &= masks[cur_bits]; + + if (cur_bits > 0) cur_accum |= (code << cur_bits); + else cur_accum = code; + + cur_bits += n_bits; + + while (cur_bits >= 8) + + { + + char_out((cur_accum & 0xff), outs); + cur_accum >>= 8; + cur_bits -= 8; + + } + + // If the next entry is going to be too big for the code size, + // then increase it, if possible. + + if (free_ent > maxcode || clear_flg) + { + + if (clear_flg) + { + + maxcode = MAXCODE(n_bits = g_init_bits); + clear_flg = false; + + } else + { + + ++n_bits; + + if (n_bits == maxbits) maxcode = maxmaxcode; + + else maxcode = MAXCODE(n_bits); + + } + + } + + if (code == EOFCode) + { + + // At EOF, write the rest of the buffer. + while (cur_bits > 0) + { + + char_out((cur_accum & 0xff), outs); + cur_accum >>= 8; + cur_bits -= 8; + } + + + flush_char(outs); + + } + + } + LZWEncoder.apply(this, arguments); + return exports; +} + -- cgit v1.2.3-70-g09d2