code: function(htOption) {
          this._bIsPainted = false;
          this._htOption = htOption;
          this._elCanvas = new Canvas(htOption.size, htOption.size);
          //this._elCanvas.width = htOption.size;
          //this._elCanvas.height = htOption.size;
          this._oContext = this._elCanvas.getContext('2d');
          //this._oContext = this._elCanvas.getContext("2d");
          this._bIsPainted = false;
          this._bSupportDataURI = null;
          this._callback = htOption.callback;
          this._bindElement = htOption.bindElement;
      }
docs: Drawing in Canvas