Function getNearestCartesianItems

src/core/core.interaction.js:168–197

* Helper function to get the items nearest to the event position for a cartesian chart * @param {Chart} chart - the chart to look at elements from * @param {Point} position - the point to be nearest to, in relative coordinates * @param {string} axis - the axes along which to measure distance * @

(chart, position, axis, intersect, useFinalPosition, includeInvisible)

 * @return {InteractionItem[]} the nearest items
 */
function getNearestCartesianItems(chart, position, axis, intersect, useFinalPosition, includeInvisible) {
  let items = [];
  const distanceMetric = getDistanceMetricForAxis(axis);
  let minDistance = Number.POSITIVE_INFINITY;

  function evaluationFunc(element, datasetIndex, index) {
    const inRange = element.inRange(position.x, position.y, useFinalPosition);
    if (intersect && !inRange) {
      return;
    }

    const center = element.getCenterPoint(useFinalPosition);
    const pointInArea = !!includeInvisible || chart.isPointInArea(center);
    if (!pointInArea && !inRange) {
      return;
    }

    const distance = distanceMetric(position, center);
    if (distance < minDistance) {
      items = [{element, datasetIndex, index}];
      minDistance = distance;
    } else if (distance === minDistance) {
      // Can have multiple items at the same distance in which case we sort by size
      items.push({element, datasetIndex, index});
    }
  }

  evaluateInteractionItems(chart, axis, position, evaluationFunc);
  return items;
}

/**
 * Helper function to get the items nearest to the event position considering all visible items in the chart