docs: function (data, colorFunc, state) {
          var gradientPixels = this._gradientPixels;
          var pixelsSingleState = gradientPixels[state] || (gradientPixels[state] = new Uint8ClampedArray(256 * 4));
          var color = [0, 0, 0, 0];
          var off = 0;
          for (var i = 0; i < 256; i++) {
              colorFunc[state](i / 255, true, color);
              pixelsSingleState[off++] = color[0];
              pixelsSingleState[off++] = color[1];
              pixelsSingleState[off++] = color[2];
              pixelsSingleState[off++] = color[3];
          }
          return pixelsSingleState;
      }