AxisX.percent-range.html.svelte component

<!--
  @component
  Generates an HTML x-axis, useful for server-side rendered charts. This component is also configured to detect if your x-scale is an ordinal scale. If so, it will place the markers in the middle of the bandwidth.

  Although this is marked as a percent-range component, you can also use it with a normal scale with no configuration needed. By default, if you have `percentRange={true}` it will use percentages, otherwise it will use pixels. This makes this component compatible with server-side and client-side rendered charts. Set the `units` prop to either `'%'` or `'px'` to override the default behavior.
 -->
<script>
  import { getContext } from 'svelte';

  const { xScale, percentRange } = getContext('LayerCake');

  /**
   * @typedef {Object} Props
   * @property {boolean} [tickMarks=false] - Show a vertical mark for each tick.
   * @property {boolean} [gridlines=true] - Show gridlines extending into the chart area.
   * @property {number} [tickMarkLength=6] - The length of the tick mark.
   * @property {boolean} [baseline=false] - Show a solid line at the bottom.
   * @property {boolean} [snapLabels=false] - Instead of centering the text labels on the first and the last items, align them to the edges of the chart.
   * @property {(d: any) => string} [format=d => d] - A function that passes the current tick value and expects a nicely formatted value in return.
   * @property {number|Array<any>|Function} [ticks] - If this is a number, it passes that along to the [d3Scale.ticks](https://github.com/d3/d3-scale) function. If this is an array, hardcodes the ticks to those values. If it's a function, passes along the default tick values and expects an array of tick values in return. If nothing, it uses the default ticks supplied by the D3 function.
   * @property {number} [tickGutter=0] - The amount of whitespace between the start of the tick and the chart drawing area (the yRange min).
   * @property {number} [dx=0] - Any optional value passed to the `dx` attribute on the text label.
   * @property {number} [dy=0] - Any optional value passed to the `dy` attribute on the text label.
   * @property {'px'|'%'} [units] - If `percentRange={true}` it defaults to `'%'`, otherwise, the default is `'px'`. Options: `'%'` or `'px'`
   */

  /** @type {Props} */
  let {
    tickMarks = false,
    gridlines = true,
    tickMarkLength = 6,
    baseline = false,
    snapLabels = false,
    format = d => d,
    ticks = undefined,
    tickGutter = 0,
    dx = 0,
    dy = 0,
    units = $percentRange === true ? '%' : 'px'
  } = $props();

  let tickLen = $derived(tickMarks === true ? (tickMarkLength ?? 6) : 0);

  let isBandwidth = $derived(typeof $xScale.bandwidth === 'function');

  /** @type {Array<any>} */
  let tickVals = $derived(
    Array.isArray(ticks)
      ? ticks
      : isBandwidth
        ? $xScale.domain()
        : typeof ticks === 'function'
          ? ticks($xScale.ticks())
          : $xScale.ticks(ticks)
  );

  let halfBand = $derived(isBandwidth ? $xScale.bandwidth() / 2 : 0);
</script>

<div class="axis x-axis" class:snapLabels>
  {#each tickVals as tick, i (tick)}
    {@const tickValUnits = $xScale(tick)}

    {#if baseline === true}
      <div class="baseline" style="top:100%; width:100%;"></div>
    {/if}

    {#if gridlines === true}
      <div class="gridline" style:left="{tickValUnits}{units}" style="top:0; bottom:0;"></div>
    {/if}
    {#if tickMarks === true}
      <div
        class="tick-mark"
        style:left="{tickValUnits + halfBand}{units}"
        style:height="{tickLen}px"
        style:bottom="{-tickLen - tickGutter}px"
      ></div>
    {/if}
    <div
      class="tick tick-{i}"
      style:left="{tickValUnits + halfBand}{units}"
      style="top:calc(100% + {tickGutter}px);"
    >
      <div
        class="text"
        style:top="{tickLen}px"
        style:transform="translate(calc(-50% + {dx}px), {dy}px)"
      >
        {format(tick)}
      </div>
    </div>
  {/each}
</div>

<style>
  .axis,
  .tick,
  .tick-mark,
  .gridline,
  .baseline {
    position: absolute;
  }
  .axis {
    width: 100%;
    height: 100%;
  }
  .tick {
    font-size: 11px;
  }

  .gridline {
    border-left: 1px dashed #aaa;
  }

  .tick-mark {
    border-left: 1px solid #aaa;
  }
  .baseline {
    border-top: 1px solid #aaa;
  }

  .tick .text {
    color: #666;
    position: relative;
    white-space: nowrap;
    transform: translateX(-50%);
  }
  /* This looks a little better at 40 percent than 50 */
  .axis.snapLabels .tick:last-child {
    transform: translateX(-40%);
  }
  .axis.snapLabels .tick.tick-0 {
    transform: translateX(40%);
  }
</style>