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BrushEdit

  • index.svelte
  • ./_components/Line.svelte
  • ./_components/Area.svelte
  • ./_components/AxisX.svelte
  • ./_components/AxisY.svelte
  • ./_components/Brush.html.svelte
  • ./_data/points.csv
<script>
  import { LayerCake, Svg, Html } from 'layercake';

  import Line from './_components/Line.svelte';
  import Area from './_components/Area.svelte';
  import AxisX from './_components/AxisX.svelte';
  import AxisY from './_components/AxisY.svelte';
  import Brush from './_components/Brush.html.svelte';

  // This example loads csv data as json using @rollup/plugin-dsv
  import data from './_data/points.csv';

  let brushExtents = [null, null];

  const xKey = 'myX';
  const yKey = 'myY';

  data.forEach(d => {
    d[yKey] = +d[yKey];
  });

  let brushedData;
  $: {
    brushedData = data.slice((brushExtents[0] || 0) * data.length, (brushExtents[1] || 1) * data.length);
    if (brushedData.length < 2) {
      brushedData = data.slice(brushExtents[0] * data.length, brushExtents[0] * data.length + 2)
    }
  }
</script>

<style>
  /*
    The wrapper div needs to have an explicit width and height in CSS.
    It can also be a flexbox child or CSS grid element.
    The point being it needs dimensions since the <LayerCake> element will
    expand to fill it.
  */
  .chart-container {
    width: 100%;
    height: 80%;
  }
  .brush-container {
    width: 100%;
    height: 20%;
  }
</style>

<div class="chart-container">
  <LayerCake
    padding={{ right: 10, bottom: 20, left: 25 }}
    x={xKey}
    y={yKey}
    yDomain={[0, null]}
    data={brushedData}
  >
    <Svg>
      <AxisX
        ticks={ticks => {
          const filtered = ticks.filter(t => t % 1 === 0);
          if (filtered.length > 7) {
            return filtered.filter((t, i) => i % 2 === 0);
          }
          return filtered;
        }}
      />
      <AxisY
        ticks={4}
      />
      <Line
        stroke='#00e047'
      />
      <Area
        fill='#00e04710'
      />
    </Svg>
  </LayerCake>
</div>

<div class="brush-container">
  <LayerCake
    padding={{ top: 5 }}
    x={xKey}
    y={yKey}
    yDomain={[0, null]}
    data={data}
  >
    <Svg>
      <Line
        stroke='#00e047'
      />
      <Area
        fill='#00e04710'
      />
    </Svg>
    <Html>
      <Brush bind:min={brushExtents[0]} bind:max={brushExtents[1]}/>
    </Html>
  </LayerCake>
</div>