/* canvas-toBlob.js
 * A canvas.toBlob() implementation.
 * 2016-05-26
 * 
 * By Eli Grey, http://eligrey.com and Devin Samarin, https://github.com/eboyjr
 * License: MIT
 *   See https://github.com/eligrey/canvas-toBlob.js/blob/master/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
      , canvas_proto = HTMLCanvasElement && HTMLCanvasElement.prototype
      , is_base64_regex = /\s*;\s*base64\s*(?:;|$)/i
      , to_data_url = "toDataURL"
      , 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;
      }
  ;
  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 && (!canvas_proto.toBlob || !canvas_proto.toBlobHD)) {
      if (!canvas_proto.toBlob)
      canvas_proto.toBlob = function(callback, type /*, ...args*/) {
            if (!type) {
              type = "image/png";
          } if (this.mozGetAsFile) {
              callback(this.mozGetAsFile("canvas", type));
              return;
          } if (this.msToBlob && /^\s*image\/png\s*(?:$|;)/i.test(type)) {
              callback(this.msToBlob());
              return;
          }
  
          var
                args = Array.prototype.slice.call(arguments, 1)
              , dataURI = this[to_data_url].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);
      };
  
      if (!canvas_proto.toBlobHD && canvas_proto.toDataURLHD) {
          canvas_proto.toBlobHD = function() {
              to_data_url = "toDataURLHD";
              var blob = this.toBlob();
              to_data_url = "toDataURL";
              return blob;
          }
      } else {
          canvas_proto.toBlobHD = canvas_proto.toBlob;
      }
  }
  }(typeof self !== "undefined" && self || typeof window !== "undefined" && window || this.content || this));