perf(player): virtualize queue list rendering

Extract a generic VirtualList.svelte component that only renders
visible rows + overscan buffer using absolute positioning in a tall
sentinel div. Queue.svelte now uses VirtualList with 64px row height
(supporting 2-line titles) instead of rendering all items.

This reduces DOM nodes from 1000+ to ~20 for large queues.
This commit is contained in:
2026-02-11 22:59:52 -08:00
parent cd443b974b
commit 6fca5bae39
2 changed files with 192 additions and 82 deletions

View File

@@ -1,18 +1,18 @@
<script lang="ts">
import { GripVertical, Play, X } from "@lucide/svelte";
import { Button } from "$lib/components/ui/button";
import VirtualList from "$lib/components/ui/VirtualList.svelte";
import { player } from "$lib/player/store.svelte";
import type { Track } from "$lib/player/types";
import { songTypeNumberLabel } from "$lib/utils/amq";
const ITEM_HEIGHT = 64;
function onRemove(id: number) {
player.remove(id);
}
function onJump(track: Track) {
// Wait, jump usually means play immediately?
// "Jump to track" -> set as current.
// If it's in the queue, we can just set currentId.
player.playId(track.id);
}
@@ -25,7 +25,7 @@
}
function onDragOver(e: DragEvent, index: number) {
e.preventDefault(); // allow drop
e.preventDefault();
if (e.dataTransfer) e.dataTransfer.dropEffect = "move";
dragOverIndex = index;
}
@@ -45,7 +45,14 @@
class="flex flex-col h-full w-full bg-background/50 backdrop-blur rounded-lg border overflow-hidden"
>
<div class="px-4 py-3 border-b flex justify-between items-center bg-muted/20">
<h3 class="font-semibold text-sm">Up Next</h3>
<h3 class="font-semibold text-sm">
Up Next
{#if player.displayQueue.length > 0}
<span class="text-muted-foreground font-normal ml-1"
>({player.displayQueue.length})</span
>
{/if}
</h3>
<Button
variant="ghost"
size="sm"
@@ -57,13 +64,14 @@
</Button>
</div>
<div class="flex-1 overflow-y-auto p-2 space-y-1">
{#if player.displayQueue.length === 0}
<div class="text-center py-8 text-muted-foreground text-sm">
Queue is empty
</div>
{:else}
{#each player.displayQueue as track, i (track.id)}
<VirtualList
items={player.displayQueue}
itemHeight={ITEM_HEIGHT}
overscan={5}
class="p-2"
key={(track) => track.id}
>
{#snippet row({ item: track, index: i })}
<div
role="button"
tabindex="0"
@@ -73,7 +81,7 @@
ondrop={(e) => onDrop(e, i)}
onclick={() => onJump(track)}
onkeydown={(e) => e.key === "Enter" && onJump(track)}
class="group flex items-center gap-2 px-3 py-2 rounded-md hover:bg-muted/50 transition-colors cursor-pointer text-sm"
class="group flex items-center gap-2 px-3 h-full rounded-md hover:bg-muted/50 transition-colors cursor-pointer text-sm"
class:active={player.currentId === track.id}
class:border-t-2={dragOverIndex === i}
class:border-primary={dragOverIndex === i}
@@ -81,20 +89,16 @@
<div
class="w-6 shrink-0 flex items-center justify-center text-xs text-muted-foreground/60 font-mono"
>
<!-- Default: Number or Active Indicator -->
<div
class="group-hover:hidden flex items-center justify-center w-full h-full"
>
{#if player.currentId === track.id}
<div
class="w-2 h-2 bg-primary rounded-full animate-pulse"
></div>
<div class="w-2 h-2 bg-primary rounded-full animate-pulse"></div>
{:else}
<span>{i + 1}</span>
{/if}
</div>
<!-- Hover: Grip Handle -->
<div
class="[@media(hover:hover)]:hidden group-hover:flex items-center justify-center w-full h-full cursor-grab active:cursor-grabbing text-muted-foreground/50 hover:text-foreground"
aria-label="Drag to reorder"
@@ -105,7 +109,7 @@
<div class="flex-1 min-w-0">
<div
class="font-medium"
class="font-medium line-clamp-2 leading-tight"
class:text-primary={player.currentId === track.id}
>
{track.animeName}
@@ -116,7 +120,7 @@
>{track.globalPercent}%</span
>
</div>
<div class="text-xs text-foreground/80">
<div class="text-xs text-foreground/80 truncate">
{track.title}
<span class="text-muted-foreground">{track.artist}</span>
</div>
@@ -125,7 +129,7 @@
<Button
variant="ghost"
size="icon"
class="h-6 w-6 opacity-50 group-hover:opacity-100 transition-opacity"
class="h-6 w-6 opacity-50 group-hover:opacity-100 transition-opacity shrink-0"
onclick={(e) => {
e.stopPropagation();
onRemove(track.id);
@@ -134,9 +138,14 @@
<X class="h-3 w-3" />
</Button>
</div>
{/each}
{/if}
{/snippet}
{#snippet empty()}
<div class="text-center py-8 text-muted-foreground text-sm">
Queue is empty
</div>
{/snippet}
</VirtualList>
</div>
<style>

View File

@@ -0,0 +1,101 @@
<!--
Generic fixed-height virtual list.
Usage:
<VirtualList items={myArray} itemHeight={64} overscan={5}>
{#snippet row({ item, index })}
<div>…</div>
{/snippet}
</VirtualList>
-->
<script lang="ts" generics="T">
import type { Snippet } from "svelte";
type Props = {
items: T[];
itemHeight: number;
overscan?: number;
class?: string;
row: Snippet<[{ item: T; index: number }]>;
empty?: Snippet;
key?: (item: T, index: number) => unknown;
};
let {
items,
itemHeight,
overscan = 5,
class: className = "",
row,
empty,
key,
}: Props = $props();
let containerEl = $state<HTMLDivElement | null>(null);
let scrollTop = $state(0);
let containerHeight = $state(0);
const totalHeight = $derived(items.length * itemHeight);
const startIndex = $derived(
Math.max(0, Math.floor(scrollTop / itemHeight) - overscan),
);
const endIndex = $derived(
Math.min(
items.length,
Math.ceil((scrollTop + containerHeight) / itemHeight) + overscan,
),
);
const visibleItems = $derived(
items.slice(startIndex, endIndex).map((item, i) => ({
item,
index: startIndex + i,
})),
);
function onScroll(e: Event) {
scrollTop = (e.target as HTMLDivElement).scrollTop;
}
$effect(() => {
if (!containerEl) return;
const ro = new ResizeObserver((entries) => {
for (const entry of entries) {
containerHeight = entry.contentRect.height;
}
});
ro.observe(containerEl);
return () => ro.disconnect();
});
</script>
<div
class="virtual-list-container {className}"
bind:this={containerEl}
onscroll={onScroll}
>
{#if items.length === 0}
{@render empty?.()}
{:else}
<div
class="virtual-list-sentinel"
style="height: {totalHeight}px; position: relative;"
>
{#each visibleItems as entry (key ? key(entry.item, entry.index) : entry.index)}
<div
class="virtual-list-item"
style="position: absolute; top: {entry.index *
itemHeight}px; left: 0; right: 0; height: {itemHeight}px;"
>
{@render row(entry)}
</div>
{/each}
</div>
{/if}
</div>
<style>
.virtual-list-container {
overflow-y: auto;
flex: 1;
}
</style>