MapLabels.html.svelte component

Adds HTML text labels based features in the data or a custom GeoJSON Feature Collection.

Param	Default	Required	Description
projection `Function`	None	yes	A D3 projection function. Pass this in as an uncalled function, e.g. `projection={geoAlbersUsa}`.
fixedAspectRatio (`number` \| `undefined`)	None	no	By default, the map fills to fit the $width and $height. If instead you want a fixed-aspect ratio, like for a server-side rendered map, set that here.
getLabel `Function`	None	yes	An accessor function to get the field to display.
getCoordinates `Function`	None	yes	An accessor function to get the `[x, y]` coordinate field. Defaults to a GeoJSON feature format.
features (`Array<Object>` \| `undefined`)	None	no	A list of labels as GeoJSON features. If unset, the plotted features will defaults to those in `$data.features`, assuming this field a list of GeoJSON features.

Used in these examples:

MapLayered

SSR Examples:

MapLayered

MapLabels.html.svelte

<!--
  @component
  Adds HTML text labels based features in the data or a custom GeoJSON Feature Collection.
 -->
<script>
  import { getContext } from 'svelte';

  const { data, width, height } = getContext('LayerCake');

  /**
   * @typedef {Object} Props
   * @property {Function} projection - A D3 projection function. Pass this in as an uncalled function, e.g. `projection={geoAlbersUsa}`.
   * @property {number|undefined} [fixedAspectRatio] - By default, the map fills to fit the $width and $height. If instead you want a fixed-aspect ratio, like for a server-side rendered map, set that here.
   * @property {Function} getLabel - An accessor function to get the field to display.
   * @property {Function} getCoordinates - An accessor function to get the `[x, y]` coordinate field. Defaults to a GeoJSON feature format.
   * @property {Array<Object>|undefined} [features] - A list of labels as GeoJSON features. If unset, the plotted features will defaults to those in `$data.features`, assuming this field a list of GeoJSON features.
   */

  /** @type {Props} */
  let { projection, fixedAspectRatio, getLabel, getCoordinates, features } = $props();

  let fitSizeRange = $derived(fixedAspectRatio ? [100, 100 / fixedAspectRatio] : [$width, $height]);

  let projectionFn = $derived(projection().fitSize(fitSizeRange, $data));

  let units = $derived(fixedAspectRatio ? '%' : 'px');
</script>

<div class="map-labels" style:aspect-ratio={fixedAspectRatio ? 1 : null}>
  {#each features || $data.features as d}
    {@const coords = projectionFn(getCoordinates(d))}
    <div
      class="map-label"
      style="
      left: {coords[0]}{units};
      top: {coords[1]}{units};
    "
    >
      {getLabel(d)}
    </div>
  {/each}
</div>

<style>
  .map-labels {
    pointer-events: none;
    position: relative;
  }
  .map-label {
    position: absolute;
    text-align: center;
    font-size: 8px;
    color: #333;
    margin-top: -3px; /* To match the SVG labels, it needs a slight tweak */
    transform: translate(-50%, -50%);
  }
</style>