1 files changed, 170 insertions, 0 deletions
diff --git a/apps/web/src/clipboard/handlers/keyframes.ts b/apps/web/src/clipboard/handlers/keyframes.ts
new file mode 100644
index 00000000..ad156e12
--- /dev/null
+++ b/apps/web/src/clipboard/handlers/keyframes.ts
@@ -0,0 +1,170 @@
+import { getKeyframeById } from "@/animation";
+import type { SelectedKeyframeRef } from "@/animation/types";
+import type { TimelineElement } from "@/timeline";
+import { PasteKeyframesCommand } from "@/commands/timeline";
+import type {
+	ClipboardHandler,
+	KeyframeClipboardCurvePatch,
+	KeyframeClipboardItem,
+} from "../types";
+
+function resolveSingleSourceElement({
+	selectedKeyframes,
+}: {
+	selectedKeyframes: SelectedKeyframeRef[];
+}) {
+	const firstKeyframe = selectedKeyframes[0];
+	if (!firstKeyframe) {
+		return null;
+	}
+
+	const sourceElement = {
+		trackId: firstKeyframe.trackId,
+		elementId: firstKeyframe.elementId,
+	};
+	const isSingleSource = selectedKeyframes.every(
+		(keyframe) =>
+			keyframe.trackId === sourceElement.trackId &&
+			keyframe.elementId === sourceElement.elementId,
+	);
+
+	return isSingleSource ? sourceElement : null;
+}
+
+function getCurvePatches({
+	element,
+	propertyPath,
+	keyframeId,
+}: {
+	element: TimelineElement;
+	propertyPath: KeyframeClipboardItem["propertyPath"];
+	keyframeId: string;
+}): KeyframeClipboardCurvePatch[] {
+	const binding = element.animations?.bindings[propertyPath];
+	if (!binding) {
+		return [];
+	}
+
+	return binding.components.flatMap((component) => {
+		const channel = element.animations?.channels[component.channelId];
+		if (channel?.kind !== "scalar") {
+			return [];
+		}
+
+		const keyframe = channel.keys.find(
+			(candidate) => candidate.id === keyframeId,
+		);
+		if (!keyframe) {
+			return [];
+		}
+
+		return [
+			{
+				componentKey: component.key,
+				patch: {
+					leftHandle: keyframe.leftHandle ?? null,
+					rightHandle: keyframe.rightHandle ?? null,
+					segmentToNext: keyframe.segmentToNext,
+					tangentMode: keyframe.tangentMode,
+				},
+			},
+		];
+	});
+}
+
+function buildClipboardItem({
+	element,
+	propertyPath,
+	keyframeId,
+}: {
+	element: TimelineElement;
+	propertyPath: KeyframeClipboardItem["propertyPath"];
+	keyframeId: string;
+}): (Omit<KeyframeClipboardItem, "timeOffset"> & { time: number }) | null {
+	const keyframe = getKeyframeById({
+		animations: element.animations,
+		propertyPath,
+		keyframeId,
+	});
+	if (!keyframe) {
+		return null;
+	}
+
+	return {
+		propertyPath,
+		time: keyframe.time,
+		value: keyframe.value,
+		interpolation: keyframe.interpolation,
+		curvePatches: getCurvePatches({
+			element,
+			propertyPath,
+			keyframeId,
+		}),
+	};
+}
+
+export const KeyframesClipboardHandler = {
+	type: "keyframes",
+
+	canCopy({ selectedKeyframes }) {
+		return selectedKeyframes.length > 0;
+	},
+
+	copy({ editor, selectedKeyframes }) {
+		const sourceElement = resolveSingleSourceElement({ selectedKeyframes });
+		if (!sourceElement) {
+			return null;
+		}
+
+		const [result] = editor.timeline.getElementsWithTracks({
+			elements: [sourceElement],
+		});
+		if (!result) {
+			return null;
+		}
+
+		const rawItems = selectedKeyframes.flatMap((keyframeRef) => {
+			const item = buildClipboardItem({
+				element: result.element,
+				propertyPath: keyframeRef.propertyPath,
+				keyframeId: keyframeRef.keyframeId,
+			});
+			return item ? [item] : [];
+		});
+		if (rawItems.length === 0) {
+			return null;
+		}
+
+		const minTime = Math.min(...rawItems.map((item) => item.time));
+		const items = rawItems
+			.map(({ time, ...item }) => ({
+				...item,
+				timeOffset: time - minTime,
+			}))
+			.sort(
+				(left, right) =>
+					left.timeOffset - right.timeOffset ||
+					left.propertyPath.localeCompare(right.propertyPath),
+			);
+
+		return {
+			type: "keyframes",
+			sourceElement,
+			items,
+		};
+	},
+
+	paste(entry, { selectedElements, time }) {
+		const targetElement = selectedElements[0];
+		if (!targetElement || entry.items.length === 0) {
+			return null;
+		}
+
+		return new PasteKeyframesCommand({
+			trackId: targetElement.trackId,
+			elementId: targetElement.elementId,
+			time,
+			clipboardItems: entry.items,
+		});
+	},
+} satisfies ClipboardHandler<"keyframes">;