text: /* canvas-toBlob.js
   * A canvas.toBlob() implementation.
   * 2011-07-13
   * 
   * By Eli Grey, http://eligrey.com and Devin Samarin, https://github.com/eboyjr
   * License: X11/MIT
   *   See LICENSE.md
   */
  
  /*global self */
  /*jslint bitwise: true, regexp: true, confusion: true, es5: true, vars: true, white: true,
    plusplus: true */
  
  /*! @source http://purl.eligrey.com/github/canvas-toBlob.js/blob/master/canvas-toBlob.js */
  
  (function(view) {
  "use strict";
  var
  	  Uint8Array = view.Uint8Array
  	, HTMLCanvasElement = view.HTMLCanvasElement
  	, is_base64_regex = /\s*;\s*base64\s*(?:;|$)/i
  	, base64_ranks
  	, decode_base64 = function(base64) {
  		var
  			  len = base64.length
  			, buffer = new Uint8Array(len / 4 * 3 | 0)
  			, i = 0
  			, outptr = 0
  			, last = [0, 0]
  			, state = 0
  			, save = 0
  			, rank
  			, code
  			, undef
  		;
  		while (len--) {
  			code = base64.charCodeAt(i++);
  			rank = base64_ranks[code-43];
  			if (rank !== 255 && rank !== undef) {
  				last[1] = last[0];
  				last[0] = code;
  				save = (save << 6) | rank;
  				state++;
  				if (state === 4) {
  					buffer[outptr++] = save >>> 16;
  					if (last[1] !== 61 /* padding character */) {
  						buffer[outptr++] = save >>> 8;
  					}
  					if (last[0] !== 61 /* padding character */) {
  						buffer[outptr++] = save;
  					}
  					state = 0;
  				}
  			}
  		}
  		// 2/3 chance there's going to be some null bytes at the end, but that
  		// doesn't really matter with most image formats.
  		// If it somehow matters for you, truncate the buffer up outptr.
  		return buffer.buffer;
  	}
  ;
  if (Uint8Array) {
  	base64_ranks = new Uint8Array([
  		  62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1
  		, -1, -1,  0, -1, -1, -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9
  		, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25
  		, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
  		, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
  	]);
  }
  if (HTMLCanvasElement && !HTMLCanvasElement.prototype.toBlob) {
  	HTMLCanvasElement.prototype.toBlob = function(callback, type /*, ...args*/) {
  		  if (!type) {
  			type = "image/png";
  		} if (this.mozGetAsFile) {
  			callback(this.mozGetAsFile("canvas", type));
  			return;
  		}
  		var
  			  args = Array.prototype.slice.call(arguments, 1)
  			, dataURI = this.toDataURL.apply(this, args)
  			, header_end = dataURI.indexOf(",")
  			, data = dataURI.substring(header_end + 1)
  			, is_base64 = is_base64_regex.test(dataURI.substring(0, header_end))
  			, blob
  		;
  		if (Blob.fake) {
  			// no reason to decode a data: URI that's just going to become a data URI again
  			blob = new Blob
  			if (is_base64) {
  				blob.encoding = "base64";
  			} else {
  				blob.encoding = "URI";
  			}
  			blob.data = data;
  			blob.size = data.length;
  		} else if (Uint8Array) {
  			if (is_base64) {
  				blob = new Blob([decode_base64(data)], {type: type});
  			} else {
  				blob = new Blob([decodeURIComponent(data)], {type: type});
  			}
  		}
  		callback(blob);
  	};
  }
  }(self));