@mui/x-charts/esm/ChartsXAxis/getVisibleLabels.js

The community edition of MUI X Charts components.

'use client';

import { getMinXTranslation } from "../internals/geometry.js";
import { getWordsByLines } from "../internals/getWordsByLines.js";

/* Returns a set of indices of the tick labels that should be visible.  */
export function getVisibleLabels(xTicks, {
  tickLabelStyle: style,
  tickLabelInterval,
  tickLabelMinGap,
  reverse,
  isMounted,
  isXInside
}) {
  const getTickLabelSize = tick => {
    if (!isMounted || tick.formattedValue === undefined) {
      return {
        width: 0,
        height: 0
      };
    }
    const tickSizes = getWordsByLines({
      style,
      needsComputation: true,
      text: tick.formattedValue
    });
    return {
      width: Math.max(...tickSizes.map(size => size.width)),
      height: Math.max(tickSizes.length * tickSizes[0].height)
    };
  };
  if (typeof tickLabelInterval === 'function') {
    return new Set(xTicks.filter((item, index) => tickLabelInterval(item.value, index)));
  }

  // Filter label to avoid overlap
  let previousTextLimit = 0;
  const direction = reverse ? -1 : 1;
  return new Set(xTicks.filter((item, labelIndex) => {
    const {
      offset,
      labelOffset
    } = item;
    const textPosition = offset + labelOffset;
    if (labelIndex > 0 && direction * textPosition < direction * (previousTextLimit + tickLabelMinGap)) {
      return false;
    }
    if (!isXInside(textPosition)) {
      return false;
    }

    /* Measuring text width is expensive, so we need to delay it as much as possible to improve performance. */
    const {
      width,
      height
    } = getTickLabelSize(item);
    const distance = getMinXTranslation(width, height, style?.angle);
    const currentTextLimit = textPosition - direction * distance / 2;
    if (labelIndex > 0 && direction * currentTextLimit < direction * (previousTextLimit + tickLabelMinGap)) {
      // Except for the first label, we skip all label that overlap with the last accepted.
      // Notice that the early return prevents `previousTextLimit` from being updated.
      return false;
    }
    previousTextLimit = textPosition + direction * distance / 2;
    return true;
  }));
}