Add Polygon and Ellipse primitives (#533)

* feat: Add Polygon primative to draw number of point polygons such as triangles, hexagon, and octagons including stars.  Includes rounding corners and adjustable insetting.

* Simplify roundedPolygonPath

* Cleanup

* Support rotation and simplify

* Simplify roundedPolygonPath if no radius

* Update docs

* feat: Add Ellipse primitive

* feat(Polygon): Suppoprt scaleX / scaleY

* feat(Polygon): Support `skewX` / `skewY` to create rhombus / parallelogram

* feat(Polygon): Support `tiltX` / `tiltY` to create trapezoid

* docs(Polygon): Cleanup example

* refactor(Polygon): Rename `curveRadius` to `cornerRadius` (alogn with `Arc`)

* docs(BarChart): Use Polygon for indicator example

* docs(BarChart): Fix indicator example when using canvas (add padding to fix <canvas> clipping)

* fix(Polygon): Apply same default classes for canvas as svg

* refactor(Polygon): Change default of `inset` to `0` (no inset instead of `1`) and positve values insets inward, negative outward

* refactor(Polygon): Change default of `tiltX` and `tiltY` to `0` and adjust logic to support adjusting each side (top/bottom, left/rigth) based on positive/negative)

Author: techniq

.changeset/nine-pens-design.md

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+---
+'layerchart': patch
+---
+
+feat: Add Polygon primitive

.changeset/wide-berries-invite.md

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+---
+'layerchart': patch
+---
+
+feat: Add Ellipse primitive

packages/layerchart/src/lib/components/Ellipse.svelte

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+<script lang="ts" module>
+  import type { CommonStyleProps, Without } from '$lib/utils/types.js';
+
+  export type EllipsePropsWithoutHTML = {
+    /**
+     * The center x position of the ellipse.
+     *
+     * @default 0
+     */
+    cx?: number;
+
+    /**
+     * The initial center x position of the ellipse.
+     *
+     * @default cx
+     */
+    initialCx?: number;
+
+    /**
+     * The center y position of the ellipse.
+     *
+     * @default 0
+     */
+    cy?: number;
+
+    /**
+     * The initial center y position of the ellipse.
+     *
+     * @default cy
+     */
+    initialCy?: number;
+
+    /**
+     * The radius of the ellipse on the x-axis.
+     *
+     * @default 1
+     */
+    rx?: number;
+
+    /**
+     * The initial radius of the ellipse on the x-axis.
+     *
+     * @default rx
+     */
+    initialRx?: number;
+
+    /**
+     * The radius of the ellipse on the y-axis.
+     *
+     * @default 1
+     */
+    ry?: number;
+
+    /**
+     * The initial radius of the ellipse on the y-axis.
+     *
+     * @default ry
+     */
+    initialRy?: number;
+
+    /**
+     * A bindable reference to the `<ellipse>` element
+     *
+     * @bindable
+     */
+    ref?: SVGEllipseElement;
+
+    motion?: MotionProp;
+  } & CommonStyleProps;
+
+  export type EllipseProps = EllipsePropsWithoutHTML &
+    Without<SVGAttributes<Element>, EllipsePropsWithoutHTML>;
+</script>
+
+<script lang="ts">
+  import { cls } from '@layerstack/tailwind';
+  import { merge } from 'lodash-es';
+
+  import { getRenderContext } from './Chart.svelte';
+  import { createMotion, type MotionProp } from '$lib/utils/motion.svelte.js';
+  import { registerCanvasComponent } from './layout/Canvas.svelte';
+  import { renderEllipse, type ComputedStylesOptions } from '$lib/utils/canvas.js';
+  import type { SVGAttributes } from 'svelte/elements';
+  import { createKey } from '$lib/utils/key.svelte.js';
+  import { layerClass } from '$lib/utils/attributes.js';
+
+  let {
+    cx = 0,
+    initialCx: initialCxProp,
+    cy = 0,
+    initialCy: initialCyProp,
+    rx = 1,
+    initialRx: initialRxProp,
+    ry = 1,
+    initialRy: initialRyProp,
+    motion,
+    fill,
+    fillOpacity,
+    stroke,
+    strokeWidth,
+    opacity,
+    class: className,
+    ref: refProp = $bindable(),
+    ...restProps
+  }: EllipseProps = $props();
+
+  let ref = $state<SVGEllipseElement>();
+
+  $effect.pre(() => {
+    refProp = ref;
+  });
+
+  const initialCx = initialCxProp ?? cx;
+  const initialCy = initialCyProp ?? cy;
+  const initialRx = initialRxProp ?? rx;
+  const initialRy = initialRyProp ?? ry;
+
+  const renderCtx = getRenderContext();
+
+  const motionCx = createMotion(initialCx, () => cx, motion);
+  const motionCy = createMotion(initialCy, () => cy, motion);
+  const motionRx = createMotion(initialRx, () => rx, motion);
+  const motionRy = createMotion(initialRy, () => ry, motion);
+
+  function render(
+    ctx: CanvasRenderingContext2D,
+    styleOverrides: ComputedStylesOptions | undefined
+  ) {
+    renderEllipse(
+      ctx,
+      { cx: motionCx.current, cy: motionCy.current, rx: motionRx.current, ry: motionRy.current },
+      styleOverrides
+        ? merge({ styles: { strokeWidth } }, styleOverrides)
+        : {
+            styles: { fill, fillOpacity, stroke, strokeWidth, opacity },
+            classes: className,
+          }
+    );
+  }
+
+  // TODO: Use objectId to work around Svelte 4 reactivity issue (even when memoizing gradients)
+  const fillKey = createKey(() => fill);
+  const strokeKey = createKey(() => stroke);
+
+  if (renderCtx === 'canvas') {
+    registerCanvasComponent({
+      name: 'Ellipse',
+      render,
+      events: {
+        click: restProps.onclick,
+        pointerdown: restProps.onpointerdown,
+        pointerenter: restProps.onpointerenter,
+        pointermove: restProps.onpointermove,
+        pointerleave: restProps.onpointerleave,
+      },
+      deps: () => [
+        motionCx.current,
+        motionCy.current,
+        motionRx.current,
+        motionRy.current,
+        fillKey.current,
+        fillOpacity,
+        strokeKey.current,
+        strokeWidth,
+        opacity,
+        className,
+      ],
+    });
+  }
+</script>
+
+{#if renderCtx === 'svg'}
+  <ellipse
+    bind:this={ref}
+    cx={motionCx.current}
+    cy={motionCy.current}
+    rx={motionRx.current}
+    ry={motionRy.current}
+    {fill}
+    fill-opacity={fillOpacity}
+    {stroke}
+    stroke-width={strokeWidth}
+    {opacity}
+    class={cls(layerClass('ellipse'), fill == null && 'fill-surface-content', className)}
+    {...restProps}
+  />
+{/if}