Chart improvements

[techniq]

• Chart
  • baseline support
    • Value guaranteed to be visible in domain (x/y). Useful with optional negative values since xDomain={[0, null]} would ignore negative values
  • TransformContext integration
  • GeoContext integration
  • TooltipContext integration
  • Add chartContext() with better types
    • Handled via ChartContext component
  • Add radial at Chart context level instead of individual components (see RadialLine examples)
  • Better group/stack integration
    • see use of createDimensionGetter()
    • Would be nice if could have derived scales (x1scale, y1scale) needed for group scales
    • See derive-scales branch in LayerCake
  • Dedicated cScale color scale instead of using rScale (which is also useful for radius, etc)
    • Integrate with <Legend>
  • Bounds integration
    • Modify xScale/yScale along with using motionScale with tweening
    • Useful with Brush (integration)
  • Improved accessor (using LayerChart's accessor)
  • Improved types
  • Simplify Chart/LayerCake/ChartContext which enables accessing LayerCake context and calculated values (width/height, scales, etc) and improves types (chartContext())

<Chart>
  <LayerCake>
    <ChartContext>
      <slot />
    </ChartContext>
  </LayerCake>
</Chart>

Layout components

• Canvas
  • Full width/height of container (like Svg) (commit)
  • scaleCanvas() integration
  • TransformContext integration
  • class support
• Svg
  • TransformContext integration
  • class support
• Html
  • class support

[techniq]

@mhkeller gathering some changes I've made (or plan to) within LayerChart, some of which might be worth pushing upstream to LayerCake (such as full width Canvas). Integration with LayerChart contexts like TransformContext, GeoContext, and TooltipContext makes some of these changes impractical to move ATM.

[mhkeller]

Thanks I'll keep an eye on it. What does full width Canvas do?

[techniq]

If you applied a padding (such as <Chart padding={{ top: 60 }}>) and zoom or translate the canvas, the chart would be "clipped" since the <canvas> is absolute positioned and inset based on the padding. The change uses context.translate() and the full container size (which aligns the results with <svg transform="...">)

The Choropleth example demonstrated this (compare to an older commit preview).

Before	After

You have to scale/zoom or drag/translate to see the issue (not really an issue with most static charts). This would be a problem with more chart types, but I've mostly only focused on Canvas support for geo (since it typically benefits the most with complex geojson). Also hoping to find a fix for the infinite loop issue before I expand out too much (might wait til Svelte 5).