docs: function() {
          if (OpenLayers.CANVAS_SUPPORTED && this.imgDiv && !this.isLoading) {
              if (!this.canvasContext) {
                  var canvas = document.createElement("canvas");
                  canvas.width = this.size.w;
                  canvas.height = this.size.h;
                  this.canvasContext = canvas.getContext("2d");
                  this.canvasContext.drawImage(this.imgDiv, 0, 0);
              }
              return this.canvasContext;
          }
      }