MapPoints.svelte component

<!--
  @component
  Generates canvas dots onto a map using [d3-geo](https://github.com/d3/d3-geo).
 -->
<script>
  /** @type {Function} projection - A D3 projection function. Pass this in as an uncalled function, e.g. `projection={geoAlbersUsa}`. */
  import { getContext } from 'svelte';

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

  /* --------------------------------------------
   * Require a D3 projection function
   */
  export let projection;

  /** @type {Number} [r=3.5] - The point's radius. */
  export let r = 3.5;

  /** @type {String} [fill='yellow'] - The point's fill color. */
  export let fill = 'yellow';

  /** @type {String} [stroke='#000'] - The point's stroke color. */
  export let stroke = '#000';

  /** @type {Number} [strokeWidth=1] - The point's stroke width. */
  export let strokeWidth = 1;

  /** @type {Number} [opacity=1] - The point's opacity. */
  export let opacity = 1;

  /** @type {Array} [features] - A list of GeoJSON features to plot. If unset, the plotted features will defaults to those in `$data.features`, assuming this field a list of GeoJSON features. */
  export let features = undefined;

  $: projectionFn = projection()
    .fitSize([$width, $height], $data);
</script>

<g class="points">
{#each (features || $data.features) as d}
  <!-- To scale the circle by size, set r to `$rGet(d.properties)` -->
  <circle
    cx={projectionFn(d.geometry.coordinates)[0]}
    cy={projectionFn(d.geometry.coordinates)[1]}
    r="{r}"
    fill="{fill}"
    stroke="{stroke}"
    stroke-width="{strokeWidth}"
    opacity="{opacity}"
  />
{/each}
</g>