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

import React, { Component } from 'react';
import PropTypes from 'prop-types';
import AnnotationHelpers from '../helpers';

export default class LineDrawComponent extends Component {

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

  getCoordinates() {
    const { slideWidth, slideHeight } = this.props;
    const { points } = this.props.annotation;

    const x1 = (points[0] / 100) * slideWidth;
    const y1 = (points[1] / 100) * slideHeight;
    const x2 = (points[2] / 100) * slideWidth;
    const y2 = (points[3] / 100) * slideHeight;

    return {
      x1,
      y1,
      x2,
      y2,
    };
  }

  render() {
    const results = this.getCoordinates();
    const { annotation, slideWidth } = this.props;
    const { x1, y1, x2, y2 } = results;

    return (
      <line
        x1={x1}
        y1={y1}
        x2={x2}
        y2={y2}
        stroke={AnnotationHelpers.getFormattedColor(annotation.color)}
        strokeLinejoin="round"
        strokeWidth={AnnotationHelpers.getStrokeWidth(annotation.thickness, slideWidth)}
        style={{ WebkitTapHighlightColor: 'rgba(0, 0, 0, 0)' }}
      />
    );
  }
}

LineDrawComponent.propTypes = {
  // Defines a version of the shape, so that we know if we need to update the component or not
  version: PropTypes.number.isRequired,
  // Defines an annotation object, which contains all the basic info we need to draw a line
  annotation: PropTypes.shape({
    points: PropTypes.arrayOf(PropTypes.number).isRequired,
    color: PropTypes.number.isRequired,
    thickness: PropTypes.number.isRequired,
  }).isRequired,
  // Defines the width of the slide (svg coordinate system), which needed in calculations
  slideWidth: PropTypes.number.isRequired,
  // Defines the height of the slide (svg coordinate system), which needed in calculations
  slideHeight: PropTypes.number.isRequired,
};