Function doSplitByStyles

src/helpers/helpers.segment.js:279–335

* @param {LineElement} line * @param {Segment[]} segments * @param {PointElement[]} points * @param {object} [segmentOptions] * @return {Segment[]}

(line, segments, points, segmentOptions)

 * @return {Segment[]}
 */
function doSplitByStyles(line, segments, points, segmentOptions) {
  const chartContext = line._chart.getContext();
  const baseStyle = readStyle(line.options);
  const {_datasetIndex: datasetIndex, options: {spanGaps}} = line;
  const count = points.length;
  const result = [];
  let prevStyle = baseStyle;
  let start = segments[0].start;
  let i = start;

  function addStyle(s, e, l, st) {
    const dir = spanGaps ? -1 : 1;
    if (s === e) {
      return;
    }
    // Style can not start/end on a skipped point, adjust indices accordingly
    s += count;
    while (points[s % count].skip) {
      s -= dir;
    }
    while (points[e % count].skip) {
      e += dir;
    }
    if (s % count !== e % count) {
      result.push({start: s % count, end: e % count, loop: l, style: st});
      prevStyle = st;
      start = e % count;
    }
  }

  for (const segment of segments) {
    start = spanGaps ? start : segment.start;
    let prev = points[start % count];
    let style;
    for (i = start + 1; i <= segment.end; i++) {
      const pt = points[i % count];
      style = readStyle(segmentOptions.setContext(createContext(chartContext, {
        type: 'segment',
        p0: prev,
        p1: pt,
        p0DataIndex: (i - 1) % count,
        p1DataIndex: i % count,
        datasetIndex
      })));
      if (styleChanged(style, prevStyle)) {
        addStyle(start, i - 1, segment.loop, prevStyle);
      }
      prev = pt;
      prevStyle = style;
    }
    if (start < i - 1) {
      addStyle(start, i - 1, segment.loop, prevStyle);
    }
  }

  return result;
}