| 1 | "use client"; |
| 2 | |
| 3 | import * as ScrollAreaPrimitive from "@radix-ui/react-scroll-area"; |
| 4 | import { |
| 5 | useEffect, |
| 6 | useMemo, |
| 7 | useRef, |
| 8 | useState, |
| 9 | type CSSProperties, |
| 10 | type ReactNode, |
| 11 | } from "react"; |
| 12 | |
| 13 | import { cn } from "@/lib/utils"; |
| 14 | import { ScrollBar } from "./scroll-area"; |
| 15 | |
| 16 | type ScrollListVirtualItem<TItem> = { |
| 17 | height: number; |
| 18 | index: number; |
| 19 | item: TItem; |
| 20 | key: string; |
| 21 | top: number; |
| 22 | }; |
| 23 | |
| 24 | export type ScrollListRange = { |
| 25 | scrollTop: number; |
| 26 | viewportHeight: number; |
| 27 | }; |
| 28 | |
| 29 | type PositionedScrollListItem<TItem> = ScrollListVirtualItem<TItem> & { |
| 30 | bottom: number; |
| 31 | }; |
| 32 | |
| 33 | type ScrollListProps<TItem> = { |
| 34 | className?: string; |
| 35 | contentClassName?: string; |
| 36 | contentStyle?: CSSProperties; |
| 37 | gap?: number; |
| 38 | getItemHeight: (item: TItem, index: number) => number; |
| 39 | getItemKey: (item: TItem, index: number) => string; |
| 40 | items: readonly TItem[]; |
| 41 | onRangeChange?: (range: ScrollListRange) => void; |
| 42 | overscan?: number; |
| 43 | paddingBottom?: number; |
| 44 | renderItem: (virtualItem: ScrollListVirtualItem<TItem>) => ReactNode; |
| 45 | }; |
| 46 | |
| 47 | function getPositionedItems<TItem>( |
| 48 | items: readonly TItem[], |
| 49 | getItemHeight: (item: TItem, index: number) => number, |
| 50 | getItemKey: (item: TItem, index: number) => string, |
| 51 | gap: number, |
| 52 | ): { |
| 53 | positionedItems: PositionedScrollListItem<TItem>[]; |
| 54 | totalMeasuredHeight: number; |
| 55 | } { |
| 56 | const positionedItems: PositionedScrollListItem<TItem>[] = []; |
| 57 | let top = 0; |
| 58 | |
| 59 | items.forEach((item, index) => { |
| 60 | const height = getItemHeight(item, index); |
| 61 | const key = getItemKey(item, index); |
| 62 | const bottom = top + height; |
| 63 | |
| 64 | positionedItems.push({ |
| 65 | bottom, |
| 66 | height, |
| 67 | index, |
| 68 | item, |
| 69 | key, |
| 70 | top, |
| 71 | }); |
| 72 | |
| 73 | top = bottom + gap; |
| 74 | }); |
| 75 | |
| 76 | return { |
| 77 | positionedItems, |
| 78 | totalMeasuredHeight: Math.max(0, top - gap), |
| 79 | }; |
| 80 | } |
| 81 | |
| 82 | export function ScrollList<TItem>({ |
| 83 | className, |
| 84 | contentClassName, |
| 85 | contentStyle, |
| 86 | gap = 0, |
| 87 | getItemHeight, |
| 88 | getItemKey, |
| 89 | items, |
| 90 | onRangeChange, |
| 91 | overscan = 0, |
| 92 | paddingBottom = 0, |
| 93 | renderItem, |
| 94 | }: ScrollListProps<TItem>) { |
| 95 | const viewportRef = useRef<HTMLDivElement | null>(null); |
| 96 | const onRangeChangeRef = useRef(onRangeChange); |
| 97 | const [scrollTop, setScrollTop] = useState(0); |
| 98 | const [viewportHeight, setViewportHeight] = useState(0); |
| 99 | const { positionedItems, totalMeasuredHeight } = useMemo( |
| 100 | () => getPositionedItems(items, getItemHeight, getItemKey, gap), |
| 101 | [gap, getItemHeight, getItemKey, items], |
| 102 | ); |
| 103 | const visibleItems = useMemo(() => { |
| 104 | const visibleStart = Math.max(0, scrollTop - overscan); |
| 105 | const visibleEnd = scrollTop + viewportHeight + overscan; |
| 106 | |
| 107 | return positionedItems.filter( |
| 108 | (item) => item.bottom + gap >= visibleStart && item.top <= visibleEnd, |
| 109 | ); |
| 110 | }, [gap, overscan, positionedItems, scrollTop, viewportHeight]); |
| 111 | |
| 112 | useEffect(() => { |
| 113 | onRangeChangeRef.current = onRangeChange; |
| 114 | }, [onRangeChange]); |
| 115 | |
| 116 | useEffect(() => { |
| 117 | const viewport = viewportRef.current; |
| 118 | if (!viewport) return; |
| 119 | |
| 120 | const updateViewportHeight = () => { |
| 121 | setViewportHeight((height) => |
| 122 | height === viewport.clientHeight ? height : viewport.clientHeight, |
| 123 | ); |
| 124 | }; |
| 125 | |
| 126 | updateViewportHeight(); |
| 127 | |
| 128 | const observer = new ResizeObserver(updateViewportHeight); |
| 129 | observer.observe(viewport); |
| 130 | |
| 131 | return () => observer.disconnect(); |
| 132 | }, []); |
| 133 | |
| 134 | useEffect(() => { |
| 135 | onRangeChangeRef.current?.({ scrollTop, viewportHeight }); |
| 136 | }, [scrollTop, viewportHeight]); |
| 137 | |
| 138 | return ( |
| 139 | <ScrollAreaPrimitive.Root |
| 140 | className={cn("relative h-full overflow-hidden", className)} |
| 141 | > |
| 142 | <ScrollAreaPrimitive.Viewport |
| 143 | ref={viewportRef} |
| 144 | className="h-full w-full" |
| 145 | onScroll={(event) => { |
| 146 | const nextScrollTop = event.currentTarget.scrollTop; |
| 147 | setScrollTop((currentScrollTop) => |
| 148 | currentScrollTop === nextScrollTop |
| 149 | ? currentScrollTop |
| 150 | : nextScrollTop, |
| 151 | ); |
| 152 | }} |
| 153 | > |
| 154 | <div |
| 155 | className={cn("relative", contentClassName)} |
| 156 | style={{ |
| 157 | ...contentStyle, |
| 158 | height: totalMeasuredHeight + paddingBottom, |
| 159 | }} |
| 160 | > |
| 161 | {visibleItems.map((virtualItem) => ( |
| 162 | <div |
| 163 | key={virtualItem.key} |
| 164 | className="absolute right-0 left-0" |
| 165 | style={{ |
| 166 | height: virtualItem.height, |
| 167 | transform: `translateY(${virtualItem.top}px)`, |
| 168 | }} |
| 169 | > |
| 170 | {renderItem(virtualItem)} |
| 171 | </div> |
| 172 | ))} |
| 173 | </div> |
| 174 | </ScrollAreaPrimitive.Viewport> |
| 175 | <ScrollBar /> |
| 176 | <ScrollAreaPrimitive.Corner /> |
| 177 | </ScrollAreaPrimitive.Root> |
| 178 | ); |
| 179 | } |
| 180 |