refactor: centralize editor interaction state

Move timeline and preview gestures into dedicated controllers so hooks stay thin around editor state and DOM events.

This also routes drag and playback synchronization through manager APIs and reuses persistent wasm surfaces so scrubbing, seeking, and preview rendering stay in sync.

Made-with: Cursor

1 files changed, 210 insertions, 0 deletions

diff --git a/apps/web/src/timeline/controllers/seek-controller.ts b/apps/web/src/timeline/controllers/seek-controller.ts
new file mode 100644
index 00000000..f32c855e
--- /dev/null
+++ b/apps/web/src/timeline/controllers/seek-controller.ts
@@ -0,0 +1,210 @@
+import type { MouseEvent as ReactMouseEvent } from "react";
+import { snappedSeekTime, type FrameRate } from "opencut-wasm";
+import { BASE_TIMELINE_PIXELS_PER_SECOND } from "@/timeline/scale";
+import { TICKS_PER_SECOND } from "@/wasm";
+
+type SeekSource = "ruler" | "tracks";
+
+interface PendingSeekSession {
+	kind: "pending";
+	source: SeekSource;
+	downX: number;
+	downY: number;
+	downTime: number;
+}
+
+type Session = { kind: "idle" } | PendingSeekSession;
+
+export interface SeekConfig {
+	zoomLevel: number;
+	duration: number;
+	isSelecting: boolean;
+	getPlayheadEl: () => HTMLDivElement | null;
+	getTrackLabelsEl: () => HTMLDivElement | null;
+	getRulerScrollEl: () => HTMLDivElement | null;
+	getTracksScrollEl: () => HTMLDivElement | null;
+	getActiveProjectFps: () => FrameRate | null;
+	clearSelectedElements: () => void;
+	seek: (time: number) => void;
+	setTimelineViewState: (viewState: {
+		zoomLevel: number;
+		scrollLeft: number;
+		playheadTime: number;
+	}) => void;
+}
+
+export interface SeekConfigRef {
+	readonly current: SeekConfig;
+}
+
+function pixelToTime({
+	clientX,
+	scrollContainer,
+	zoomLevel,
+	duration,
+}: {
+	clientX: number;
+	scrollContainer: HTMLDivElement;
+	zoomLevel: number;
+	duration: number;
+}): number {
+	const rect = scrollContainer.getBoundingClientRect();
+	const mouseX = clientX - rect.left;
+	const scrollLeft = scrollContainer.scrollLeft;
+
+	const rawTimeSeconds = Math.max(
+		0,
+		Math.min(
+			duration / TICKS_PER_SECOND,
+			(mouseX + scrollLeft) / (BASE_TIMELINE_PIXELS_PER_SECOND * zoomLevel),
+		),
+	);
+
+	return Math.round(rawTimeSeconds * TICKS_PER_SECOND);
+}
+
+function isClickGesture({
+	event,
+	session,
+}: {
+	event: ReactMouseEvent;
+	session: PendingSeekSession;
+}): boolean {
+	const deltaX = Math.abs(event.clientX - session.downX);
+	const deltaY = Math.abs(event.clientY - session.downY);
+	const deltaTime = event.timeStamp - session.downTime;
+
+	return deltaX <= 5 && deltaY <= 5 && deltaTime <= 500;
+}
+
+export class SeekController {
+	private session: Session = { kind: "idle" };
+	private readonly configRef: SeekConfigRef;
+
+	constructor(deps: { configRef: SeekConfigRef }) {
+		this.configRef = deps.configRef;
+		this.onTracksMouseDown = this.onTracksMouseDown.bind(this);
+		this.onRulerMouseDown = this.onRulerMouseDown.bind(this);
+		this.onTracksClick = this.onTracksClick.bind(this);
+		this.onRulerClick = this.onRulerClick.bind(this);
+	}
+
+	private get config(): SeekConfig {
+		return this.configRef.current;
+	}
+
+	destroy(): void {
+		this.session = { kind: "idle" };
+	}
+
+	onTracksMouseDown(event: ReactMouseEvent): void {
+		this.beginPendingSeek({ event, source: "tracks" });
+	}
+
+	onRulerMouseDown(event: ReactMouseEvent): void {
+		this.beginPendingSeek({ event, source: "ruler" });
+	}
+
+	onTracksClick(event: ReactMouseEvent): void {
+		this.handleClick({ event, source: "tracks" });
+	}
+
+	onRulerClick(event: ReactMouseEvent): void {
+		this.handleClick({ event, source: "ruler" });
+	}
+
+	private beginPendingSeek({
+		event,
+		source,
+	}: {
+		event: ReactMouseEvent;
+		source: SeekSource;
+	}): void {
+		if (event.button !== 0) return;
+
+		this.session = {
+			kind: "pending",
+			source,
+			downX: event.clientX,
+			downY: event.clientY,
+			downTime: event.timeStamp,
+		};
+	}
+
+	private handleClick({
+		event,
+		source,
+	}: {
+		event: ReactMouseEvent;
+		source: SeekSource;
+	}): void {
+		const shouldProcess = this.shouldProcessClick({ event, source });
+		this.session = { kind: "idle" };
+
+		if (!shouldProcess) return;
+
+		this.config.clearSelectedElements();
+		this.seekFromEvent({ event, source });
+	}
+
+	private shouldProcessClick({
+		event,
+		source,
+	}: {
+		event: ReactMouseEvent;
+		source: SeekSource;
+	}): boolean {
+		if (this.session.kind !== "pending") return false;
+		if (this.session.source !== source) return false;
+		if (!isClickGesture({ event, session: this.session })) return false;
+		if (this.config.isSelecting) return false;
+
+		const target = event.target as HTMLElement;
+		if (this.config.getPlayheadEl()?.contains(target)) return false;
+
+		if (this.config.getTrackLabelsEl()?.contains(target)) {
+			this.config.clearSelectedElements();
+			return false;
+		}
+
+		return true;
+	}
+
+	private seekFromEvent({
+		event,
+		source,
+	}: {
+		event: ReactMouseEvent;
+		source: SeekSource;
+	}): void {
+		const scrollContainer =
+			source === "ruler"
+				? this.config.getRulerScrollEl()
+				: this.config.getTracksScrollEl();
+		if (!scrollContainer) return;
+
+		const rawTime = pixelToTime({
+			clientX: event.clientX,
+			scrollContainer,
+			zoomLevel: this.config.zoomLevel,
+			duration: this.config.duration,
+		});
+
+		const fps = this.config.getActiveProjectFps();
+		const time =
+			fps != null
+				? (snappedSeekTime({
+						time: rawTime,
+						duration: this.config.duration,
+						rate: fps,
+					}) ?? rawTime)
+				: rawTime;
+
+		this.config.seek(time);
+		this.config.setTimelineViewState({
+			zoomLevel: this.config.zoomLevel,
+			scrollLeft: scrollContainer.scrollLeft,
+			playheadTime: time,
+		});
+	}
+}