bigbluebutton-Github/bigbluebutton-html5/imports/ui/components/whiteboard/annotations/ellipse/component.jsx

import React from 'react';
import PropTypes from 'prop-types';
import AnnotationHelpers from '../helpers.js';

export default class EllipseDrawComponent extends React.Component {
  constructor(props) {
    super(props);
  }

  shouldComponentUpdate(nextProps, nextState) {
    return this.props.version != nextProps.version;
  }

  getCoordinates() {
    // x1 and y1 - coordinates of the ellipse's top left corner
    // x2 and y2 - coordinates of the ellipse's bottom right corner
    const x1 = this.props.annotation.points[0];
    const y1 = this.props.annotation.points[1];
    const x2 = this.props.annotation.points[2];
    const y2 = this.props.annotation.points[3];

    // rx - horizontal radius
    // ry - vertical radius
    // cx and cy - coordinates of the ellipse's center
    let rx = (x2 - x1) / 2;
    let ry = (y2 - y1) / 2;
    const cx = (rx + x1) * this.props.slideWidth / 100;
    const cy = (ry + y1) * this.props.slideHeight / 100;
    rx = Math.abs(rx / 100 * this.props.slideWidth);
    ry = Math.abs(ry / 100 * this.props.slideHeight);

    return {
      cx,
      cy,
      rx,
      ry,
    };
  }

  render() {
    const results = this.getCoordinates();
    return (
      <ellipse
        cx={results.cx}
        cy={results.cy}
        rx={results.rx}
        ry={results.ry}
        fill="none"
        stroke={AnnotationHelpers.formatColor(this.props.annotation.color)}
        strokeWidth={AnnotationHelpers.getStrokeWidth(this.props.annotation.thickness, this.props.slideWidth)}
        style={this.props.style}
      />
    );
  }
}

EllipseDrawComponent.defaultProps = {
  style: {
    WebkitTapHighlightColor: 'rgba(0, 0, 0, 0)',
  },
};