feat: 引入 yuxiang-kit 课程组件源码与运行时

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/course-runtime/canvas/useCanvasScale.ts

@@ -0,0 +1,45 @@
+import { useEffect, useState } from "react";
+
+interface CanvasScaleOptions {
+	width: number;
+	height: number;
+	maxScale: number;
+}
+
+function calculateScale({
+	width,
+	height,
+	maxScale,
+}: CanvasScaleOptions): number {
+	if (typeof window === "undefined") return maxScale;
+	return Math.min(
+		window.innerWidth / width,
+		window.innerHeight / height,
+		maxScale,
+	);
+}
+
+export function useCanvasScale({
+	width,
+	height,
+	maxScale,
+}: CanvasScaleOptions): number {
+	const [scale, setScale] = useState(() =>
+		calculateScale({ width, height, maxScale }),
+	);
+
+	useEffect(() => {
+		const updateScale = () =>
+			setScale(calculateScale({ width, height, maxScale }));
+		updateScale();
+		window.addEventListener("resize", updateScale);
+		window.visualViewport?.addEventListener("resize", updateScale);
+
+		return () => {
+			window.removeEventListener("resize", updateScale);
+			window.visualViewport?.removeEventListener("resize", updateScale);
+		};
+	}, [height, maxScale, width]);
+
+	return scale;
+}