diff options
Diffstat (limited to 'includes/js/dojox/encoding/compression/lzw.js')
-rw-r--r-- | includes/js/dojox/encoding/compression/lzw.js | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/includes/js/dojox/encoding/compression/lzw.js b/includes/js/dojox/encoding/compression/lzw.js new file mode 100644 index 0000000..5e0cca7 --- /dev/null +++ b/includes/js/dojox/encoding/compression/lzw.js @@ -0,0 +1,91 @@ +if(!dojo._hasResource["dojox.encoding.compression.lzw"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code. +dojo._hasResource["dojox.encoding.compression.lzw"] = true; +dojo.provide("dojox.encoding.compression.lzw"); +dojo.require("dojox.encoding.bits"); + +(function(){ + var _bits = function(x){ + var w = 1; + for(var v = 2; x >= v; v <<= 1, ++w); + return w; + }; + + dojox.encoding.compression.lzw.Encoder = function(n){ + this.size = n; + this.init(); + }; + + dojo.extend(dojox.encoding.compression.lzw.Encoder, { + init: function(){ + this.dict = {}; + for(var i = 0; i < this.size; ++i){ + this.dict[String.fromCharCode(i)] = i; + } + this.width = _bits(this.code = this.size); + this.p = ""; + }, + encode: function(value, stream){ + var c = String.fromCharCode(value), p = this.p + c, r = 0; + // if already in the dictionary + if(p in this.dict){ + this.p = p; + return r; + } + stream.putBits(this.dict[this.p], this.width); + // if we need to increase the code length + if((this.code & (this.code + 1)) == 0){ + stream.putBits(this.code++, r = this.width++); + } + // add new string + this.dict[p] = this.code++; + this.p = c; + return r + this.width; + }, + flush: function(stream){ + if(this.p.length == 0){ + return 0; + } + stream.putBits(this.dict[this.p], this.width); + this.p = ""; + return this.width; + } + }); + + dojox.encoding.compression.lzw.Decoder = function(n){ + this.size = n; + this.init(); + }; + + dojo.extend(dojox.encoding.compression.lzw.Decoder, { + init: function(){ + this.codes = new Array(this.size); + for(var i = 0; i < this.size; ++i){ + this.codes[i] = String.fromCharCode(i); + } + this.width = _bits(this.size); + this.p = -1; + }, + decode: function(stream){ + var c = stream.getBits(this.width), v; + if(c < this.codes.length){ + v = this.codes[c]; + if(this.p >= 0){ + this.codes.push(this.codes[this.p] + v.substr(0, 1)); + } + }else{ + if((c & (c + 1)) == 0){ + this.codes.push(""); + ++this.width; + return ""; + } + var x = this.codes[this.p]; + v = x + x.substr(0, 1); + this.codes.push(v); + } + this.p = c; + return v; + } + }); +})(); + +} |