From 897bc631f73ad1266c6b8e4b5487655e48c9fbd5 Mon Sep 17 00:00:00 2001
From: Vavency <vavency@gmail.com>
Date: Wed, 21 Feb 2024 16:17:13 +0000
Subject: [PATCH] Optimized pattern drawing in MkModPlayer

---
 .../frontend/src/components/MkModPlayer.vue   | 464 +++++++++++++-----
 packages/frontend/src/scripts/chiptune2.ts    |  46 ++
 2 files changed, 386 insertions(+), 124 deletions(-)

diff --git a/packages/frontend/src/components/MkModPlayer.vue b/packages/frontend/src/components/MkModPlayer.vue
index f61144cbc..75053cbc3 100644
--- a/packages/frontend/src/components/MkModPlayer.vue
+++ b/packages/frontend/src/components/MkModPlayer.vue
@@ -7,14 +7,17 @@
 </div>
 
 <div v-else class="mod-player-enabled">
-	<div class="pattern-display" @click="togglePattern()">
+	<div class="pattern-display" @click="togglePattern()" @scroll="scrollHandler" @scrollend="scrollEndHandle">
 		<div v-if="patternHide" class="pattern-hide">
 			<b><i class="ph-eye ph-bold ph-lg"></i> Pattern Hidden</b>
 			<span>{{ i18n.ts.clickToShow }}</span>
 		</div>
+		<span class="patternShadowTop"></span>
+		<span class="patternShadowBottom"></span>
 		<canvas ref="displayCanvas" class="pattern-canvas"></canvas>
 	</div>
 	<div class="controls">
+		<input v-if="patternScrollSliderShow" ref="patternScrollSlider" v-model="patternScrollSliderPos" class="pattern-slider" type="range" min="0" max="100" step="0.01" style=""/>
 		<button class="play" @click="playPause()">
 			<i v-if="playing" class="ph-pause ph-bold ph-lg"></i>
 			<i v-else class="ph-play ph-bold ph-lg"></i>
@@ -33,43 +36,30 @@
 </template>
 
 <script lang="ts" setup>
-import { ref, nextTick, computed } from 'vue';
+import { ref, nextTick, computed, watch, onDeactivated, onMounted } from 'vue';
 import * as Misskey from 'misskey-js';
 import { i18n } from '@/i18n.js';
 import { defaultStore } from '@/store.js';
 import { ChiptuneJsPlayer, ChiptuneJsConfig } from '@/scripts/chiptune2.js';
+import { isTouchUsing } from '@/scripts/touch.js';
+
+const colours = {
+	background: '#000000',
+	foreground: {
+		default: '#ffffff',
+		quarter: '#ffff00',
+		instr: '#80e0ff',
+		volume: '#80ff80',
+		fx: '#ff80e0',
+		operant: '#ffe080',
+	},
+};
 
 const CHAR_WIDTH = 6;
 const CHAR_HEIGHT = 12;
 const ROW_OFFSET_Y = 10;
-
-const colours = {
-	background: '#000000',
-	default: {
-		active: '#ffffff',
-		inactive: '#808080',
-	},
-	quarter: {
-		active: '#ffff00',
-		inactive: '#ffe135',
-	},
-	instr: {
-		active: '#80e0ff',
-		inactive: '#0099cc',
-	},
-	volume: {
-		active: '#80ff80',
-		inactive: '#008000',
-	},
-	fx: {
-		active: '#ff80e0',
-		inactive: '#800060',
-	},
-	operant: {
-		active: '#ffe080',
-		inactive: '#806000',
-	},
-};
+const MAX_TIME_SPENT = 50;
+const MAX_TIME_PER_ROW = 15;
 
 const props = defineProps<{
 	module: Misskey.entities.DriveFile
@@ -79,29 +69,57 @@ const isSensitive = computed(() => { return props.module.isSensitive; });
 const url = computed(() => { return props.module.url; });
 let hide = ref((defaultStore.state.nsfw === 'force') ? true : isSensitive.value && (defaultStore.state.nsfw !== 'ignore'));
 let patternHide = ref(false);
-let firstFrame = ref(true);
 let playing = ref(false);
 let displayCanvas = ref<HTMLCanvasElement>();
 let progress = ref<HTMLProgressElement>();
 let position = ref(0);
+let patternScrollSlider = ref<HTMLProgressElement>();
+let patternScrollSliderShow = ref(false);
+let patternScrollSliderPos = ref(0);
 const player = ref(new ChiptuneJsPlayer(new ChiptuneJsConfig()));
 
-const rowBuffer = 24;
+const maxRowNumbers = 0xFF;
+const rowBuffer = 26;
 let buffer = null;
 let isSeeking = false;
+let firstFrame = true;
+let lastPattern = -1;
+let lastDrawnRow = -1;
+let numberRowCanvas = new OffscreenCanvas(2 * CHAR_WIDTH + 1, maxRowNumbers * CHAR_HEIGHT + 1);
+let alreadyHiddenOnce = false;
+let alreadyDrawn = [false];
+let patternTime = { 'current': 0, 'max': 0, 'initial': 0 };
 
-player.value.load(url.value).then((result) => {
-	buffer = result;
-	try {
-		player.value.play(buffer);
-		progress.value!.max = player.value.duration();
-		display();
-	} catch (err) {
-		console.warn(err);
+function bakeNumberRow() {
+	let ctx = numberRowCanvas.getContext('2d', { alpha: false }) as OffscreenCanvasRenderingContext2D;
+	ctx.font = '10px monospace';
+
+	for (let i = 0; i < maxRowNumbers; i++) {
+		let rowText = i.toString(16);
+		if (rowText.length === 1) rowText = '0' + rowText;
+
+		ctx.fillStyle = colours.foreground.default;
+		if (i % 4 === 0) ctx.fillStyle = colours.foreground.quarter;
+
+		ctx.fillText(rowText, 0, 10 + i * 12);
 	}
-	player.value.stop();
-}).catch((error) => {
-	console.error(error);
+}
+
+onMounted(() => {
+	player.value.load(url.value).then((result) => {
+		buffer = result;
+		try {
+			player.value.play(buffer);
+			progress.value!.max = player.value.duration();
+			bakeNumberRow();
+			display();
+		} catch (err) {
+			console.warn(err);
+		}
+		player.value.stop();
+	}).catch((error) => {
+		console.error(error);
+	});
 });
 
 function playPause() {
@@ -133,7 +151,7 @@ function stop(noDisplayUpdate = false) {
 	if (!noDisplayUpdate) {
 		try {
 			player.value.play(buffer);
-			display();
+			display(true);
 		} catch (err) {
 			console.warn(err);
 		}
@@ -162,104 +180,256 @@ function performSeek() {
 
 function toggleVisible() {
 	hide.value = !hide.value;
-	if (!hide.value && patternHide.value) {
-		firstFrame.value = true;
-		patternHide.value = false;
+	if (!hide.value) {
+		lastPattern = -1;
+		lastDrawnRow = -1;
 	}
 	nextTick(() => { stop(hide.value); });
 }
 
 function togglePattern() {
 	patternHide.value = !patternHide.value;
-	if (!patternHide.value) {
-		if (player.value.getRow() === 0) {
-			try {
-				player.value.play(buffer);
-				display();
-			} catch (err) {
-				console.warn(err);
-			}
-			player.value.stop();
+	handleScrollBarEnable();
+
+	if (player.value.getRow() === 0 && player.value.getPattern() === 0) {
+		try {
+			player.value.play(buffer);
+			display(true);
+		} catch (err) {
+			console.warn(err);
 		}
+		player.value.stop();
+	} else {
+		display(true);
 	}
 }
 
-function display() {
-	if (!displayCanvas.value) {
-		stop();
-		return;
-	}
-
-	if (patternHide.value) return;
-
-	if (firstFrame.value) {
-		firstFrame.value = false;
-		patternHide.value = true;
-	}
-
+function drawPattern() {
+	if (!displayCanvas.value) return;
 	const canvas = displayCanvas.value;
 
+	const startTime = performance.now();
 	const pattern = player.value.getPattern();
+	const nbRows = player.value.getPatternNumRows(pattern);
 	const row = player.value.getRow();
+	const halfbuf = rowBuffer / 2;
+	const minRow = row - halfbuf;
+	const maxRow = row + halfbuf;
+
+	let rowDif = 0;
+
 	let nbChannels = 0;
 	if (player.value.currentPlayingNode) {
 		nbChannels = player.value.currentPlayingNode.nbChannels;
 	}
-	if (canvas.width !== 12 + 84 * nbChannels + 2) {
-		canvas.width = 12 + 84 * nbChannels + 2;
-		canvas.height = 12 * rowBuffer;
-	}
-	const nbRows = player.value.getPatternNumRows(pattern);
-	const ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
-	ctx.font = '10px monospace';
-	ctx.fillStyle = colours.background;
-	ctx.fillRect(0, 0, canvas.width, canvas.height);
-	ctx.fillStyle = colours.default.inactive;
-	for (let rowOffset = 0; rowOffset < rowBuffer; rowOffset++) {
-		const rowToDraw = row - rowBuffer / 2 + rowOffset;
-		if (rowToDraw >= 0 && rowToDraw < nbRows) {
-			const active = (rowToDraw === row) ? 'active' : 'inactive';
-			let rowText = parseInt(rowToDraw).toString(16);
-			if (rowText.length === 1) {
-				rowText = '0' + rowText;
-			}
-			ctx.fillStyle = colours.default[active];
-			if (rowToDraw % 4 === 0) {
-				ctx.fillStyle = colours.quarter[active];
-			}
-			ctx.fillText(rowText, 0, 10 + rowOffset * 12);
-			for (let channel = 0; channel < nbChannels; channel++) {
-				const part = player.value.getPatternRowChannel(pattern, rowToDraw, channel);
-				const baseOffset = (2 + (part.length + 1) * channel) * CHAR_WIDTH;
-				const baseRowOffset = ROW_OFFSET_Y + rowOffset * CHAR_HEIGHT;
+	if (pattern === lastPattern) {
+		rowDif = row - lastDrawnRow;
+	} else {
+		if (patternTime.initial !== 0 && !alreadyHiddenOnce) {
+			const trackerTime = player.value.currentPlayingNode.getProcessTime();
 
-				ctx.fillStyle = colours.default[active];
-				ctx.fillText('|', baseOffset, baseRowOffset);
-
-				const note = part.substring(0, 3);
-				ctx.fillStyle = colours.default[active];
-				ctx.fillText(note, baseOffset + CHAR_WIDTH, baseRowOffset);
-
-				const instr = part.substring(4, 6);
-				ctx.fillStyle = colours.instr[active];
-				ctx.fillText(instr, baseOffset + CHAR_WIDTH * 5, baseRowOffset);
-
-				const volume = part.substring(6, 9);
-				ctx.fillStyle = colours.volume[active];
-				ctx.fillText(volume, baseOffset + CHAR_WIDTH * 7, baseRowOffset);
-
-				const fx = part.substring(10, 11);
-				ctx.fillStyle = colours.fx[active];
-				ctx.fillText(fx, baseOffset + CHAR_WIDTH * 11, baseRowOffset);
-
-				const op = part.substring(11, 13);
-				ctx.fillStyle = colours.operant[active];
-				ctx.fillText(op, baseOffset + CHAR_WIDTH * 12, baseRowOffset);
+			if (patternTime.initial + trackerTime.max > MAX_TIME_SPENT && trackerTime.max + patternTime.max > MAX_TIME_PER_ROW) {
+				alreadyHiddenOnce = true;
+				togglePattern();
+				return;
 			}
 		}
+
+		patternTime = { 'current': 0, 'max': 0, 'initial': 0 };
+		alreadyDrawn = [];
+		if (canvas.width !== (12 + 84 * nbChannels + 2)) canvas.width = 12 + 84 * nbChannels + 2;
+		if (canvas.height !== (12 * nbRows)) canvas.height = 12 * nbRows;
+	}
+
+	const ctx = canvas.getContext('2d', { alpha: false, desynchronized: true }) as CanvasRenderingContext2D;
+	if (ctx.font !== '10px monospace') ctx.font = '10px monospace';
+	ctx.imageSmoothingEnabled = false;
+	if (pattern !== lastPattern) {
+		ctx.fillStyle = colours.background;
+		ctx.fillRect(0, 0, canvas.width, canvas.height);
+		ctx.drawImage( numberRowCanvas, 0, 0 );
+	}
+
+	ctx.fillStyle = colours.foreground.default;
+	for (let rowOffset = minRow + rowDif; rowOffset < maxRow + rowDif; rowOffset++) {
+		const rowToDraw = rowOffset - rowDif;
+
+		if (alreadyDrawn[rowToDraw] === true) continue;
+
+		if (rowToDraw >= 0 && rowToDraw < nbRows) {
+			const baseOffset = 2 * CHAR_WIDTH;
+			const baseRowOffset = ROW_OFFSET_Y + rowToDraw * CHAR_HEIGHT;
+			let done = drawRow(ctx, rowToDraw, nbChannels, pattern, baseOffset, baseRowOffset);
+
+			alreadyDrawn[rowToDraw] = done;
+		}
+	}
+
+	lastDrawnRow = row;
+	lastPattern = pattern;
+
+	patternTime.current = performance.now() - startTime;
+	if (patternTime.initial !== 0 && patternTime.current > patternTime.max) patternTime.max = patternTime.current;
+	else if (patternTime.initial === 0) patternTime.initial = patternTime.current;
+}
+
+function drawPetternPreview() {
+	if (!displayCanvas.value) return;
+	const canvas = displayCanvas.value;
+
+	const pattern = player.value.getPattern();
+	const nbRows = player.value.getPatternNumRows(pattern);
+	const row = player.value.getRow();
+	const halfbuf = rowBuffer / 2;
+	alreadyDrawn = [];
+
+	let nbChannels = 0;
+	if (player.value.currentPlayingNode) {
+		nbChannels = player.value.currentPlayingNode.nbChannels;
+	}
+	if (canvas.width !== (12 + 84 * nbChannels + 2)) canvas.width = 12 + 84 * nbChannels + 2;
+	if (canvas.height !== (12 * rowBuffer)) canvas.height = 12 * rowBuffer;
+
+	const ctx = canvas.getContext('2d', { alpha: false }) as CanvasRenderingContext2D;
+	ctx.font = '10px monospace';
+	ctx.imageSmoothingEnabled = false;
+	ctx.fillStyle = colours.background;
+	ctx.fillRect(0, 0, canvas.width, canvas.height);
+	ctx.drawImage( numberRowCanvas, 0, (halfbuf - row) * CHAR_HEIGHT );
+
+	for (let rowOffset = 0; rowOffset < rowBuffer; rowOffset++) {
+		const rowToDraw = rowOffset + row - halfbuf;
+
+		if (rowToDraw >= 0 && rowToDraw < nbRows) {
+			const baseOffset = 2 * CHAR_WIDTH;
+			const baseRowOffset = ROW_OFFSET_Y + rowOffset * CHAR_HEIGHT;
+			drawRow(ctx, rowToDraw, nbChannels, pattern, baseOffset, baseRowOffset);
+		} else if (rowToDraw >= 0) {
+			const baseRowOffset = ROW_OFFSET_Y + rowOffset * CHAR_HEIGHT;
+			ctx.fillStyle = colours.background;
+			ctx.fillRect(0, baseRowOffset - CHAR_HEIGHT, CHAR_WIDTH * 2, baseRowOffset);
+		}
+	}
+
+	lastPattern = -1;
+	lastDrawnRow = -1;
+}
+
+function drawRow(ctx: CanvasRenderingContext2D, row: number, channels: number, pattern: number, drawX = (2 * CHAR_WIDTH), drawY = ROW_OFFSET_Y) {
+	if (!player.value.currentPlayingNode) return false;
+	if (alreadyDrawn[row]) return true;
+	const spacer = 11;
+	const space = ' ';
+	let seperators = '';
+	let note = '';
+	let instr = '';
+	let volume = '';
+	let fx = '';
+	let op = '';
+	for (let channel = 0; channel < channels; channel++) {
+		const part = player.value.getPatternRowChannel(pattern, row, channel);
+
+		seperators += '|' + space.repeat( spacer + 2 );
+		note += part.substring(0, 3) + space.repeat( spacer );
+		instr += part.substring(4, 6) + space.repeat( spacer + 1 );
+		volume += part.substring(6, 9) + space.repeat( spacer );
+		fx += part.substring(10, 11) + space.repeat( spacer + 2 );
+		op += part.substring(11, 13) + space.repeat( spacer + 1 );
+	}
+
+	ctx.fillStyle = colours.foreground.default;
+	ctx.fillText(seperators, drawX, drawY);
+
+	ctx.fillStyle = colours.foreground.default;
+	ctx.fillText(note, drawX + CHAR_WIDTH, drawY);
+
+	ctx.fillStyle = colours.foreground.instr;
+	ctx.fillText(instr, drawX + CHAR_WIDTH * 5, drawY);
+
+	ctx.fillStyle = colours.foreground.volume;
+	ctx.fillText(volume, drawX + CHAR_WIDTH * 7, drawY);
+
+	ctx.fillStyle = colours.foreground.fx;
+	ctx.fillText(fx, drawX + CHAR_WIDTH * 11, drawY);
+
+	ctx.fillStyle = colours.foreground.operant;
+	ctx.fillText(op, drawX + CHAR_WIDTH * 12, drawY);
+
+	return true;
+}
+
+function display(skipOptimizationChecks = false) {
+	if (!displayCanvas.value || !displayCanvas.value.parentElement) {
+		stop();
+		return;
+	}
+
+	if (patternHide.value && !skipOptimizationChecks) return;
+
+	if (firstFrame) {
+		// Changing it to false should enable pattern display by default.
+		patternHide.value = true;
+		handleScrollBarEnable();
+		firstFrame = false;
+	}
+
+	const row = player.value.getRow();
+	const pattern = player.value.getPattern();
+
+	if ( row === lastDrawnRow && pattern === lastPattern && !skipOptimizationChecks) return;
+
+	// Size vs speed
+	if (patternHide.value) drawPetternPreview();
+	else drawPattern();
+
+	displayCanvas.value.style.top = !patternHide.value ? 'calc( 50% - ' + (row * CHAR_HEIGHT) + 'px )' : '0%';
+}
+
+let suppressScrollSliderWatcher = false;
+
+function scrollHandler() {
+	suppressScrollSliderWatcher = true;
+
+	if (!patternScrollSlider.value) return;
+	if (!displayCanvas.value) return;
+	if (!displayCanvas.value.parentElement) return;
+
+	patternScrollSliderPos.value = (displayCanvas.value.parentElement.scrollLeft) / (displayCanvas.value.width - displayCanvas.value.parentElement.offsetWidth) * 100;
+	patternScrollSlider.value.style.opacity = '1';
+}
+
+function scrollEndHandle() {
+	suppressScrollSliderWatcher = false;
+
+	if (!patternScrollSlider.value) return;
+	patternScrollSlider.value.style.opacity = '';
+}
+
+function handleScrollBarEnable() {
+	patternScrollSliderShow.value = (!patternHide.value && !isTouchUsing);
+	if (patternScrollSliderShow.value !== true) return;
+
+	if (!displayCanvas.value) return;
+	if (!displayCanvas.value.parentElement) return;
+	if (firstFrame) {
+		patternScrollSliderShow.value = (12 + 84 * player.value.getPatternNumRows(player.value.getPattern()) + 2 > displayCanvas.value.parentElement.offsetWidth);
+	} else {
+		patternScrollSliderShow.value = (displayCanvas.value.width > displayCanvas.value.parentElement.offsetWidth);
 	}
 }
 
+watch(patternScrollSliderPos, () => {
+	if (suppressScrollSliderWatcher) return;
+	if (!displayCanvas.value) return;
+	if (!displayCanvas.value.parentElement) return;
+
+	displayCanvas.value.parentElement.scrollLeft = (displayCanvas.value.width - displayCanvas.value.parentElement.offsetWidth) * patternScrollSliderPos.value / 100;
+});
+
+onDeactivated(() => {
+	stop();
+});
+
 </script>
 
 <style lang="scss" scoped>
@@ -290,6 +460,7 @@ function display() {
 		cursor: pointer;
 		top: 12px;
 		right: 12px;
+		z-index: 4;
 	}
 
 	> .pattern-display {
@@ -299,22 +470,55 @@ function display() {
 		overflow-y: hidden;
 		background-color: black;
 		text-align: center;
-		.pattern-canvas {
-			background-color: black;
-			height: 100%;
+		max-height: 312px; /* magic_number = CHAR_HEIGHT * rowBuffer, needs to be in px */
+
+		scrollbar-width: none;
+
+		&::-webkit-scrollbar {
+			display: none;
 		}
+
+		.pattern-canvas {
+			position: relative;
+			background-color: black;
+			image-rendering: pixelated;
+			pointer-events: none;
+			z-index: 0;
+		}
+
+		.patternShadowTop {
+			background: #00000080;
+			width: 100%;
+			height: calc( 50% - 14px );
+			translate: 0 -100%;
+			top: calc( 50% - 14px );
+			position: absolute;
+			pointer-events: none;
+			z-index: 2;
+		}
+
+		.patternShadowBottom {
+			background: #00000080;
+			width: 100%;
+			height: calc( 50% - 12px );
+			top: calc( 50% - 1px );
+			position: absolute;
+			pointer-events: none;
+			z-index: 2;
+		}
+
 		.pattern-hide {
 			display: flex;
 			flex-direction: column;
 			justify-content: center;
 			align-items: center;
 			background: rgba(64, 64, 64, 0.3);
-			backdrop-filter: blur(2em);
+			backdrop-filter: var(--modalBgFilter);
 			color: #fff;
 			font-size: 12px;
 
 			position: absolute;
-			z-index: 0;
+			z-index: 4;
 			width: 100%;
 			height: 100%;
 
@@ -328,7 +532,7 @@ function display() {
 		display: flex;
 		width: 100%;
 		background-color: var(--bg);
-		z-index: 1;
+		z-index: 5;
 
 		> * {
 			padding: 4px 8px;
@@ -353,6 +557,18 @@ function display() {
 			margin: 4px 8px;
 			overflow-x: hidden;
 
+			&.pattern-slider {
+				position: absolute;
+				width: calc( 100% - 8px * 2 );
+				top: calc( 100% - 21px * 3 );
+				opacity: 0%;
+				transition: opacity 0.2s;
+
+				&:hover {
+					opacity: 100%;
+				}
+			}
+
 			&:focus {
 				outline: none;
 
diff --git a/packages/frontend/src/scripts/chiptune2.ts b/packages/frontend/src/scripts/chiptune2.ts
index e52adb07d..5a5b1d6c2 100644
--- a/packages/frontend/src/scripts/chiptune2.ts
+++ b/packages/frontend/src/scripts/chiptune2.ts
@@ -150,6 +150,27 @@ ChiptuneJsPlayer.prototype.getRow = function () {
 	return 0;
 };
 
+ChiptuneJsPlayer.prototype.getNumPatterns = function () {
+	if (this.currentPlayingNode && this.currentPlayingNode.modulePtr) {
+		return libopenmpt._openmpt_module_get_num_patterns(this.currentPlayingNode.modulePtr);
+	}
+	return 0;
+};
+
+ChiptuneJsPlayer.prototype.getCurrentSpeed = function () {
+	if (this.currentPlayingNode && this.currentPlayingNode.modulePtr) {
+		return libopenmpt._openmpt_module_get_current_speed(this.currentPlayingNode.modulePtr);
+	}
+	return 0;
+};
+
+ChiptuneJsPlayer.prototype.getCurrentTempo = function () {
+	if (this.currentPlayingNode && this.currentPlayingNode.modulePtr) {
+		return libopenmpt._openmpt_module_get_current_tempo(this.currentPlayingNode.modulePtr);
+	}
+	return 0;
+};
+
 ChiptuneJsPlayer.prototype.getPatternNumRows = function (pattern: number) {
 	if (this.currentPlayingNode && this.currentPlayingNode.modulePtr) {
 		return libopenmpt._openmpt_module_get_pattern_num_rows(this.currentPlayingNode.modulePtr, pattern);
@@ -164,6 +185,20 @@ ChiptuneJsPlayer.prototype.getPatternRowChannel = function (pattern: number, row
 	return '';
 };
 
+ChiptuneJsPlayer.prototype.getCtls = function () {
+	if (this.currentPlayingNode && this.currentPlayingNode.modulePtr) {
+		return libopenmpt._openmpt_module_get_ctls(this.currentPlayingNode.modulePtr);
+	}
+	return 0;
+};
+
+ChiptuneJsPlayer.prototype.version = function () {
+	if (this.currentPlayingNode && this.currentPlayingNode.modulePtr) {
+		return libopenmpt._openmpt_get_library_version();
+	}
+	return 0;
+};
+
 ChiptuneJsPlayer.prototype.createLibopenmptNode = function (buffer, config: object) {
 	const maxFramesPerChunk = 4096;
 	const processNode = this.audioContext.createScriptProcessor(2048, 0, 2);
@@ -178,6 +213,7 @@ ChiptuneJsPlayer.prototype.createLibopenmptNode = function (buffer, config: obje
 	processNode.paused = false;
 	processNode.leftBufferPtr = libopenmpt._malloc(4 * maxFramesPerChunk);
 	processNode.rightBufferPtr = libopenmpt._malloc(4 * maxFramesPerChunk);
+	processNode.perf = { 'current': 0, 'max': 0 };
 	processNode.cleanup = function () {
 		if (this.modulePtr !== 0) {
 			libopenmpt._openmpt_module_destroy(this.modulePtr);
@@ -205,7 +241,13 @@ ChiptuneJsPlayer.prototype.createLibopenmptNode = function (buffer, config: obje
 	processNode.togglePause = function () {
 		this.paused = !this.paused;
 	};
+	processNode.getProcessTime = function() {
+		const max = this.perf.max;
+		this.perf.max = 0;
+		return { 'current': this.perf.current, 'max': max };
+	};
 	processNode.onaudioprocess = function (e) {
+		let startTimeP1 = performance.now();
 		const outputL = e.outputBuffer.getChannelData(0);
 		const outputR = e.outputBuffer.getChannelData(1);
 		let framesToRender = outputL.length;
@@ -231,11 +273,13 @@ ChiptuneJsPlayer.prototype.createLibopenmptNode = function (buffer, config: obje
 
 		const currentPattern = libopenmpt._openmpt_module_get_current_pattern(this.modulePtr);
 		const currentRow = libopenmpt._openmpt_module_get_current_row(this.modulePtr);
+		startTimeP1 = startTimeP1 - performance.now();
 		if (currentPattern !== this.patternIndex) {
 			processNode.player.fireEvent('onPatternChange');
 		}
 		processNode.player.fireEvent('onRowChange', { index: currentRow });
 
+		const startTimeP2 = performance.now();
 		while (framesToRender > 0) {
 			const framesPerChunk = Math.min(framesToRender, maxFramesPerChunk);
 			const actualFramesPerChunk = libopenmpt._openmpt_module_read_float_stereo(this.modulePtr, this.context.sampleRate, framesPerChunk, this.leftBufferPtr, this.rightBufferPtr);
@@ -262,6 +306,8 @@ ChiptuneJsPlayer.prototype.createLibopenmptNode = function (buffer, config: obje
 			this.cleanup();
 			error ? processNode.player.fireEvent('onError', { type: 'openmpt' }) : processNode.player.fireEvent('onEnded');
 		}
+		this.perf.current = performance.now() - startTimeP2 + startTimeP1;
+		if (this.perf.current > this.perf.max) this.perf.max = this.perf.current;
 	};
 	return processNode;
 };