/
PlaybackManager.ts
246 lines (208 loc) · 6.22 KB
/
PlaybackManager.ts
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import {ValueDispatcher} from '../events';
import type {Scene, SceneDescriptionReload, Slide} from '../scenes';
export enum PlaybackState {
Playing,
Rendering,
Paused,
Presenting,
}
/**
* A general class for managing a sequence of scenes.
*
* @remarks
* This class provides primitive operations that can be executed on a scene
* sequence, such as {@link progress} or {@link seek}.
*
* @internal
*/
export class PlaybackManager {
/**
* Triggered when the active scene changes.
*
* @eventProperty
*/
public get onSceneChanged() {
if (this.currentSceneReference === null) {
throw new Error('PlaybackManager has not been properly initialized');
}
return this.currentSceneReference.subscribable;
}
/**
* Triggered when the scenes get recalculated.
*
* @remarks
* This event indicates that the timing of at least one scene has changed.
*
* @eventProperty
*/
public get onScenesRecalculated() {
return this.scenes.subscribable;
}
public frame = 0;
public speed = 1;
public fps = 30;
public duration = 0;
public finished = false;
public slides: Slide[] = [];
public previousScene: Scene | null = null;
public state = PlaybackState.Paused;
public get currentScene(): Scene {
if (this.currentSceneReference === null) {
throw new Error('PlaybackManager has not been properly initialized');
}
return this.currentSceneReference.current;
}
public set currentScene(scene: Scene) {
if (!scene) {
throw new Error('Invalid scene.');
}
this.currentSceneReference ??= new ValueDispatcher<Scene>(scene);
this.currentSceneReference.current = scene;
}
private currentSceneReference: ValueDispatcher<Scene> | null = null;
private scenes = new ValueDispatcher<Scene[]>([]);
public setup(scenes: Scene[]) {
this.scenes.current = scenes;
this.currentScene = scenes[0];
}
public async progress() {
this.finished = await this.next();
return this.finished;
}
public async seek(frame: number): Promise<boolean> {
if (
frame <= this.frame ||
(this.currentScene.isCached() && this.currentScene.lastFrame < frame)
) {
const scene = this.findBestScene(frame);
if (scene !== this.currentScene) {
this.previousScene = null;
this.currentScene = scene;
this.frame = this.currentScene.firstFrame;
await this.currentScene.reset();
} else if (this.frame >= frame) {
this.previousScene = null;
this.frame = this.currentScene.firstFrame;
await this.currentScene.reset();
}
}
this.finished = false;
while (this.frame < frame && !this.finished) {
this.finished = await this.next();
}
return this.finished;
}
public async goBack() {
let target = this.currentScene.slides.getCurrent();
if (target && this.currentScene.slides.isWaiting()) {
const index = this.slides.indexOf(target);
target = this.slides[index - 1];
}
await this.seekSlide(target);
}
public async goForward() {
const current = this.currentScene.slides.getCurrent();
const index = this.slides.indexOf(current!);
await this.seekSlide(this.slides[index + 1]);
}
public async goTo(slideId: string) {
await this.seekSlide(this.slides.find(slide => slide.id === slideId));
}
private async seekSlide(slide: Slide | null = null) {
if (!slide) return;
const {id, scene} = slide;
if (this.currentScene !== scene || this.currentScene.slides.didHappen(id)) {
this.previousScene = null;
this.currentScene = scene;
this.frame = this.currentScene.firstFrame;
this.currentScene.slides.setTarget(id);
await this.currentScene.reset();
}
this.finished = false;
this.currentScene.slides.setTarget(id);
while (!this.currentScene.slides.isWaitingFor(id) && !this.finished) {
this.finished = await this.next();
}
this.currentScene.slides.setTarget(null);
return this.finished;
}
public async reset() {
this.previousScene = null;
this.currentScene = this.scenes.current[0];
this.frame = 0;
await this.currentScene.reset();
}
public reload(description?: SceneDescriptionReload<never>) {
this.scenes.current.forEach(scene => scene.reload(description));
}
public async recalculate() {
this.previousScene = null;
this.slides = [];
const speed = this.speed;
this.frame = 0;
this.speed = 1;
const scenes: Scene[] = [];
try {
for (const scene of this.scenes.current) {
await scene.recalculate(frame => {
this.frame = frame;
});
this.slides.push(...scene.slides.onChanged.current);
scenes.push(scene);
}
} finally {
this.speed = speed;
}
this.scenes.current = scenes;
this.duration = this.frame;
}
private async next(): Promise<boolean> {
if (this.previousScene) {
await this.previousScene.next();
if (this.currentScene.isFinished()) {
this.previousScene = null;
}
}
this.frame += this.speed;
if (this.currentScene.isFinished()) {
return true;
}
await this.currentScene.next();
if (this.previousScene && this.currentScene.isAfterTransitionIn()) {
this.previousScene = null;
}
if (this.currentScene.canTransitionOut()) {
this.previousScene = this.currentScene;
const nextScene = this.getNextScene(this.previousScene);
if (nextScene) {
this.currentScene = nextScene;
await this.currentScene.reset(this.previousScene);
}
if (!nextScene || this.currentScene.isAfterTransitionIn()) {
this.previousScene = null;
}
}
return this.currentScene.isFinished();
}
private findBestScene(frame: number): Scene {
let lastScene = this.scenes.current[0];
for (const scene of this.scenes.current) {
if (!scene.isCached() || scene.lastFrame > frame) {
return scene;
}
lastScene = scene;
}
return lastScene;
}
private getNextScene(scene?: Scene): Scene | null {
const scenes = this.scenes.current;
if (!scene) {
return scenes[0];
}
const index = scenes.findIndex(s => s === scene);
if (index < 0) {
return null;
}
return scenes[index + 1] ?? null;
}
}