ui : add unified ScrollCarousel component

Single carousel component with top/center variants, gap and scroll options, and hover-revealed chevrons. Rename the HorizontalScrollCarousel accessibility story accordingly.

Assisted-by: pi

tools/ui/src/lib/components/ui/scroll-carousel/index.ts

@@ -0,0 +1,3 @@
+import ScrollCarousel from './scroll-carousel.svelte';
+
+export { ScrollCarousel };

tools/ui/src/lib/components/ui/scroll-carousel/scroll-carousel.svelte

@@ -0,0 +1,129 @@
+<script lang="ts">
+	import { ChevronLeft, ChevronRight } from '@lucide/svelte';
+	import { cn } from '$lib/components/ui/utils';
+	import { ICON_CLASS_DEFAULT } from '$lib/constants';
+	import { useScrollCarousel } from '$lib/hooks/use-scroll-carousel.svelte';
+	import type { Snippet } from 'svelte';
+
+	interface Props {
+		children: Snippet;
+		/** External carousel hook for callers that need to drive it (e.g. scrollToCenter). */
+		carousel?: ReturnType<typeof useScrollCarousel>;
+		/** Classes for the outer relative wrapper. */
+		class?: string;
+		/** Classes for the scrollable overflow container. */
+		containerClass?: string;
+		/** Classes for the min-w-max content wrapper. */
+		innerClass?: string;
+		/** Tailwind gap class applied to the content wrapper. */
+		gapSize?: string;
+		/** Arrow placement and styling. */
+		variant?: 'top' | 'center';
+		/** Called with whether the content overflows the container. */
+		onScrollableChange?: (isScrollable: boolean) => void;
+		/** Pixels scrolled per arrow click; defaults to ~2/3 of the container width. */
+		scrollBy?: number;
+	}
+
+	let {
+		carousel: externalCarousel,
+		children,
+		class: className = '',
+		containerClass = '',
+		gapSize = '3',
+		innerClass = '',
+		onScrollableChange,
+		scrollBy,
+		variant = 'top'
+	}: Props = $props();
+
+	const internalCarousel = $derived(useScrollCarousel(onScrollableChange));
+	const carousel = $derived(externalCarousel ?? internalCarousel);
+
+	const isCenter = $derived(variant === 'center');
+
+	function scrollLeft(event?: MouseEvent) {
+		event?.stopPropagation();
+		event?.preventDefault();
+
+		const container = carousel.scrollContainer;
+
+		if (!container) return;
+
+		container.scrollBy({ behavior: 'smooth', left: -(scrollBy ?? container.clientWidth * 0.67) });
+	}
+
+	function scrollRight(event?: MouseEvent) {
+		event?.stopPropagation();
+		event?.preventDefault();
+
+		const container = carousel.scrollContainer;
+
+		if (!container) return;
+
+		container.scrollBy({ behavior: 'smooth', left: scrollBy ?? container.clientWidth * 0.67 });
+	}
+
+	export function resetScroll() {
+		const container = carousel.scrollContainer;
+
+		if (!container) return;
+
+		container.scrollLeft = 0;
+		setTimeout(() => carousel.updateScrollButtons(), 0);
+	}
+</script>
+
+<div
+	class={cn('group relative', !isCenter && 'flex items-center', className)}
+	style={!isCenter ? 'scroll-padding: 1rem;' : undefined}
+>
+	<button
+		class={cn(
+			'absolute z-10 flex h-6 w-6 items-center justify-center rounded-full shadow-md transition-opacity',
+			isCenter
+				? 'top-1/2 left-4 -translate-y-1/2 bg-background/25 backdrop-blur-xs hover:bg-background/45 disabled:pointer-events-none disabled:opacity-0'
+				: 'left-2 bg-muted backdrop-blur-sm hover:bg-accent',
+			!isCenter &&
+				(carousel.canScrollLeft
+					? 'opacity-0 group-hover:opacity-100'
+					: 'pointer-events-none opacity-0')
+		)}
+		{...isCenter ? { disabled: !carousel.canScrollLeft } : {}}
+		onclick={scrollLeft}
+		aria-label="Scroll left"
+	>
+		<ChevronLeft class={ICON_CLASS_DEFAULT} />
+	</button>
+
+	<div
+		class={cn('scrollbar-hide overflow-x-auto', containerClass)}
+		bind:this={carousel.scrollContainer}
+		onscroll={carousel.updateScrollButtons}
+	>
+		<div
+			class={cn('flex min-w-max', `gap-${gapSize}`, innerClass)}
+			bind:this={carousel.contentContainer}
+		>
+			{@render children?.()}
+		</div>
+	</div>
+
+	<button
+		class={cn(
+			'absolute z-10 flex h-6 w-6 items-center justify-center rounded-full shadow-md transition-opacity',
+			isCenter
+				? 'top-1/2 right-4 -translate-y-1/2 bg-background/25 backdrop-blur-xs hover:bg-background/45 disabled:pointer-events-none disabled:opacity-0'
+				: 'right-2 bg-muted backdrop-blur-sm hover:bg-accent',
+			!isCenter &&
+				(carousel.canScrollRight
+					? 'opacity-0 group-hover:opacity-100'
+					: 'pointer-events-none opacity-0')
+		)}
+		{...isCenter ? { disabled: !carousel.canScrollRight } : {}}
+		onclick={scrollRight}
+		aria-label="Scroll right"
+	>
+		<ChevronRight class={ICON_CLASS_DEFAULT} />
+	</button>
+</div>

tools/ui/tests/stories/a11y/ScrollCarousel.a11y.stories.svelte

@@ -1,15 +1,15 @@
 <script module lang="ts">
 	import { defineMeta } from '@storybook/addon-svelte-csf';
-	import HorizontalScrollCarousel from '$lib/components/app/misc/HorizontalScrollCarousel.svelte';
+	import { ScrollCarousel } from '$lib/components/ui/scroll-carousel';
 	import { expect, waitFor } from 'storybook/test';
 
 	const { Story } = defineMeta({
-		component: HorizontalScrollCarousel,
+		component: ScrollCarousel,
 		parameters: {
 			layout: 'centered'
 		},
 		tags: ['!dev'],
-		title: 'Components/HorizontalScrollCarousel/Accessibility'
+		title: 'Components/ScrollCarousel/Accessibility'
 	});
 </script>
 
@@ -33,10 +33,10 @@
 >
 	<div>
 		<button type="button">before</button>
-		<HorizontalScrollCarousel class="w-96">
+		<ScrollCarousel class="w-96" variant="center">
 			<div class="h-12 w-12 shrink-0 bg-muted"></div>
 			<div class="h-12 w-12 shrink-0 bg-muted"></div>
-		</HorizontalScrollCarousel>
+		</ScrollCarousel>
 		<button type="button">after</button>
 	</div>
 </Story>
@@ -60,10 +60,10 @@
 >
 	<div>
 		<button type="button">before</button>
-		<HorizontalScrollCarousel class="w-48">
+		<ScrollCarousel class="w-48" variant="center">
 			{#each [...Array(20).keys()] as i (i)}
 				<div class="h-12 w-24 shrink-0 bg-muted">{i}</div>
 			{/each}
-		</HorizontalScrollCarousel>
+		</ScrollCarousel>
 	</div>
 </Story>