webaudiofont/npm/src/ticker.ts

Soundfonts for web. About of 2000 musical instruments. GM MIDI compatible.

'use strict'

class WebAudioFontTicker {
	stateStop = 1;
	statePlay = 2;
	stateEnd = 3;
	state = this.stateStop;
	stepDuration = 0.1;
	lastPosition = 0;
	playLoop(player: WebAudioFontPlayer, audioContext: AudioContext, loopStart: number, loopPosition: number, loopEnd: number, queue: ChordQueue[]) {
		this.startTicks(audioContext, function (when: number, from: number, to: number) {
			for (var i = 0; i < queue.length; i++) {
				var note = queue[i];
				if (note.when >= from && note.when < to) {
					var start = when + note.when - from;
					player.queueWaveTable(audioContext, note.destination, note.preset, start, note.pitch, note.duration, note.volume, note.slides);
				}
			}
		}, loopStart, loopPosition, loopEnd, function (at) {
			player.cancelQueue(audioContext);
		});
	};
	startTicks(audioContext: AudioContext, onTick: (when: number, from: number, to: number) => void, loopStart: number, loopPosition: number, loopEnd: number, onEnd: (loopPosition: number) => void) {
		if (this.state == this.stateStop) {
			this.state = this.statePlay;
			this.tick(audioContext, audioContext.currentTime, onTick, loopStart, loopPosition, loopEnd, onEnd);
		}
	};
	tick(audioContext: AudioContext, nextAudioTime: number, onTick: (when: number, from: number, to: number) => void, loopStart: number, loopPosition: number, loopEnd: number, onEnd: (loopPosition: number) => void) {
		this.lastPosition = loopPosition;
		if (this.state == this.stateEnd) {
			this.state = this.stateStop;
			onEnd(loopPosition);
		} else {
			if (this.state == this.statePlay) {
				if (nextAudioTime - this.stepDuration < audioContext.currentTime) {
					if (loopPosition + this.stepDuration < loopEnd) {
						var from = loopPosition;
						var to = loopPosition + this.stepDuration;
						onTick(nextAudioTime, from, to);
						loopPosition = to;
					} else {
						var from = loopPosition;
						var to = loopEnd;
						onTick(nextAudioTime, from, to);
						from = loopStart;
						to = loopStart + this.stepDuration - (loopEnd - loopPosition);
						if (to < loopEnd) {
							onTick(nextAudioTime + (loopEnd - loopPosition), from, to);
							loopPosition = to;
						} else {
							loopPosition = loopEnd;
						}
					}
					nextAudioTime = nextAudioTime + this.stepDuration;
					if (nextAudioTime < audioContext.currentTime) {
						nextAudioTime = audioContext.currentTime
					}
				}
				var me = this;
				window.requestAnimationFrame(function (time) {
					me.tick(audioContext, nextAudioTime, onTick, loopStart, loopPosition, loopEnd, onEnd);
				});
			}
		}
	}
	cancel() {
		if (this.state == this.statePlay) {
			this.state = this.stateEnd;
		}
	};
}