feat: move/resize multiple elements

1 files changed, 71 insertions, 0 deletions

diff --git a/apps/web/src/lib/timeline/group-move/snap.ts b/apps/web/src/lib/timeline/group-move/snap.ts
new file mode 100644
index 00000000..3502ae30
--- /dev/null
+++ b/apps/web/src/lib/timeline/group-move/snap.ts
@@ -0,0 +1,71 @@
+import type { SceneTracks } from "@/lib/timeline";
+import {
+	findSnapPoints,
+	snapToNearestPoint,
+	type SnapPoint,
+} from "@/lib/timeline/snap-utils";
+import type { MoveGroup } from "./types";
+
+export function snapGroupEdges({
+	group,
+	anchorStartTime,
+	tracks,
+	playheadTime,
+	zoomLevel,
+}: {
+	group: MoveGroup;
+	anchorStartTime: number;
+	tracks: SceneTracks;
+	playheadTime: number;
+	zoomLevel: number;
+}): {
+	snappedAnchorStartTime: number;
+	snapPoint: SnapPoint | null;
+} {
+	const snapPoints = findSnapPoints({
+		tracks,
+		playheadTime,
+		excludeElementIds: new Set(group.members.map((member) => member.elementId)),
+	});
+
+	let closestSnapDistance = Infinity;
+	let snappedAnchorStartTime = anchorStartTime;
+	let snapPoint: SnapPoint | null = null;
+
+	for (const member of group.members) {
+		const memberStartTime = anchorStartTime + member.timeOffset;
+		const memberStartSnap = snapToNearestPoint({
+			targetTime: memberStartTime,
+			snapPoints,
+			zoomLevel,
+		});
+		if (
+			memberStartSnap.snapPoint &&
+			memberStartSnap.snapDistance < closestSnapDistance
+		) {
+			closestSnapDistance = memberStartSnap.snapDistance;
+			snappedAnchorStartTime = memberStartSnap.snappedTime - member.timeOffset;
+			snapPoint = memberStartSnap.snapPoint;
+		}
+
+		const memberEndSnap = snapToNearestPoint({
+			targetTime: memberStartTime + member.duration,
+			snapPoints,
+			zoomLevel,
+		});
+		if (
+			memberEndSnap.snapPoint &&
+			memberEndSnap.snapDistance < closestSnapDistance
+		) {
+			closestSnapDistance = memberEndSnap.snapDistance;
+			snappedAnchorStartTime =
+				memberEndSnap.snappedTime - member.duration - member.timeOffset;
+			snapPoint = memberEndSnap.snapPoint;
+		}
+	}
+
+	return {
+		snappedAnchorStartTime,
+		snapPoint,
+	};
+}