text: // Copyright 2019 Google LLC
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //      http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  import { createElement } from "./utils";
  
  function createStop(offset, color, opacity = undefined) {
    return { offset, color, opacity };
  }
  
  export default class Gradient {
    constructor(tag, attributes = {}) {
      this.tag_ = tag;
      this.attributes_ = attributes;
      this.stops_ = [];
    }
  
    addStop(offset, color, opacity = undefined) {
      this.stops_.push(createStop(offset, color, opacity));
      return this;
    }
  
    render() {
      const gradient = createElement(this.tag_, this.attributes_);
      for (const { offset, color, opacity } of this.stops_) {
        const attributes = Object.assign(
          { offset, "stop-color": color },
          opacity && { "stop-opacity": opacity }
        );
        gradient.appendChild(createElement("stop", attributes));
      }
      return gradient;
    }
  }
  