Add album color fullscreen background

app/components/Player/Fullscreen.vue

@@ -44,12 +44,9 @@ nuxtApp.hook("page:finish", () => {
 		v-show="fullscreen"
 	>
 		<template v-if="song">
-			<NuxtImg
+			<PlayerFullscreenBackgroundWash
 				:src="GET_FILE(song.album.file)"
-				:alt="song.name"
-				width="500"
-				height="500"
-				class="background"
+				:active="fullscreen"
 			/>
 		</template>
 
@@ -95,17 +92,6 @@ nuxtApp.hook("page:finish", () => {
 	}
 }
 
-.background {
-	position: absolute;
-	top: -25%;
-	left: -25%;
-
-	width: 100%;
-	height: 100%;
-	object-fit: cover;
-	filter: blur(40px);
-}
-
 .screen-container {
 	position: fixed;
 	top: 0;

app/components/Player/Fullscreen/Background/Wash.vue

@@ -0,0 +1,106 @@
+<script setup lang="ts">
+import { extractPalette } from "./palette"
+
+const props = defineProps<{ src: string; active: boolean }>()
+const canvas = ref<HTMLCanvasElement | null>(null)
+const palette = ref<[number, number, number][]>([])
+let frame = 0
+let startedAt = 0
+
+const fallback: [number, number, number][] = [
+	[30, 35, 55], [70, 45, 75], [35, 75, 85], [105, 65, 45],
+]
+
+function loadArtwork() {
+	const image = new Image()
+	image.crossOrigin = "anonymous"
+	image.onload = () => {
+		try {
+			palette.value = extractPalette(image)
+		} catch {
+			palette.value = fallback
+		}
+	}
+	image.onerror = () => { palette.value = fallback }
+	image.src = props.src
+}
+
+function draw(now: number) {
+	const element = canvas.value
+	const context = element?.getContext("2d")
+	if (!element || !context) return
+	if (!startedAt) startedAt = now
+	const time = (now - startedAt) / 1000
+	const width = 112
+	const height = Math.max(72, Math.round(width * element.clientHeight / Math.max(1, element.clientWidth)))
+	if (element.width !== width || element.height !== height) {
+		element.width = width
+		element.height = height
+	}
+	const image = context.createImageData(width, height)
+	const colors = palette.value.length ? palette.value : fallback
+	const fields = colors.map((_, index) => {
+		const angle = (index / colors.length) * Math.PI * 2
+		return {
+			x: 0.5 + Math.cos(angle + time * 0.13) * 0.34,
+			y: 0.5 + Math.sin(angle + time * 0.11) * 0.32,
+		}
+	})
+	for (let y = 0; y < height; y++) {
+		for (let x = 0; x < width; x++) {
+			const px = x / width
+			const py = y / height
+			const weights = fields.map((field) => {
+				const dx = px - field.x
+				const dy = py - field.y
+				return 1 / (0.2 + dx * dx + dy * dy)
+			})
+			const total = weights.reduce((sum, weight) => sum + weight, 0)
+			const color = [0, 1, 2].map((channel) => Math.round(
+				colors.reduce((sum, item, index) => sum + item[channel] * weights[index], 0) / total * 0.52,
+			))
+			const offset = (y * width + x) * 4
+			image.data[offset] = color[0]
+			image.data[offset + 1] = color[1]
+			image.data[offset + 2] = color[2]
+			image.data[offset + 3] = 255
+		}
+	}
+	context.putImageData(image, 0, 0)
+	if (props.active) frame = requestAnimationFrame(draw)
+}
+
+watch(() => props.src, loadArtwork)
+watch(() => props.active, (active) => {
+	if (active) {
+		startedAt = 0
+		frame = requestAnimationFrame(draw)
+	} else {
+		cancelAnimationFrame(frame)
+	}
+})
+
+onMounted(() => {
+	loadArtwork()
+	if (props.active) frame = requestAnimationFrame(draw)
+})
+
+onBeforeUnmount(() => {
+	cancelAnimationFrame(frame)
+})
+</script>
+
+<template>
+	<canvas ref="canvas" class="background-wash" aria-hidden="true" />
+</template>
+
+<style scoped>
+.background-wash {
+	position: absolute;
+	inset: 0;
+	width: 100%;
+	height: 100%;
+	filter: blur(42px) saturate(1.2);
+	transform: scale(1.08);
+}
+</style>

app/components/Player/Fullscreen/Background/palette.ts

@@ -0,0 +1,32 @@
+type RGB = [number, number, number]
+
+/** Sample a small CPU histogram and return the most common album colors. */
+export function extractPalette(image: HTMLImageElement, size = 48): RGB[] {
+	const canvas = document.createElement("canvas")
+	canvas.width = size
+	canvas.height = size
+	const context = canvas.getContext("2d", { willReadFrequently: true })
+	if (!context) return [[30, 35, 55], [70, 45, 75], [35, 75, 85], [105, 65, 45]]
+
+	context.drawImage(image, 0, 0, size, size)
+	const pixels = context.getImageData(0, 0, size, size).data
+	const bins = new Map<number, { count: number; r: number; g: number; b: number }>()
+	for (let i = 0; i < pixels.length; i += 4) {
+		if (pixels[i + 3] < 96) continue
+		const r = pixels[i] >> 3
+		const g = pixels[i + 1] >> 3
+		const b = pixels[i + 2] >> 3
+		const key = (r << 10) | (g << 5) | b
+		const bin = bins.get(key) ?? { count: 0, r: 0, g: 0, b: 0 }
+		bin.count++
+		bin.r += pixels[i]
+		bin.g += pixels[i + 1]
+		bin.b += pixels[i + 2]
+		bins.set(key, bin)
+	}
+	const colors = [...bins.values()]
+		.sort((a, b) => b.count - a.count)
+		.slice(0, 8)
+		.map((bin) => [bin.r / bin.count, bin.g / bin.count, bin.b / bin.count] as RGB)
+	return colors.length ? colors : [[30, 35, 55], [70, 45, 75], [35, 75, 85], [105, 65, 45]]
+}