fix: v-sizeディレクティブの動作を修正 (#8249)

* Fix size directive behavior not activated

* calc

* wip

* cache computed classes

* fix Vue3では使えなくなった

* 不要なIntersection Observerを削除

* comment

packages/client/src/directives/get-size.ts

@@ -1,34 +1,55 @@
 import { Directive } from 'vue';
 
+const mountings = new Map<Element, {
+	resize: ResizeObserver;
+	intersection?: IntersectionObserver;
+	fn: (w: number, h: number) => void;
+}>();
+
+function calc(src: Element) {
+	const info = mountings.get(src);
+	const height = src.clientHeight;
+	const width = src.clientWidth;
+
+	if (!info) return;
+
+	// アクティベート前などでsrcが描画されていない場合
+	if (!height) {
+		// IntersectionObserverで表示検出する
+		if (!info.intersection) {
+			info.intersection = new IntersectionObserver(entries => {
+				if (entries.some(entry => entry.isIntersecting)) calc(src);
+			});
+		}
+		info.intersection.observe(src);
+		return;
+	}
+	if (info.intersection) {
+		info.intersection.disconnect()
+		delete info.intersection;
+	};
+
+	info.fn(width, height);
+};
+
 export default {
 	mounted(src, binding, vn) {
-		const calc = () => {
-			const height = src.clientHeight;
-			const width = src.clientWidth;
 
-			// 要素が(一時的に)DOMに存在しないときは計算スキップ
-			if (height === 0) return;
-
-			binding.value(width, height);
-		};
-
-		calc();
-
-		// Vue3では使えなくなった
-		// 無くても大丈夫か...？
-		// TODO: ↑大丈夫じゃなかったので解決策を探す
-		//vn.context.$on('hook:activated', calc);
-
-		const ro = new ResizeObserver((entries, observer) => {
-			calc();
+		const resize = new ResizeObserver((entries, observer) => {
+			calc(src);
 		});
-		ro.observe(src);
+		resize.observe(src);
 
-		src._get_size_ro_ = ro;
+		mountings.set(src, { resize, fn: binding.value, });
+		calc(src);
 	},
 
 	unmounted(src, binding, vn) {
 		binding.value(0, 0);
-		src._get_size_ro_.unobserve(src);
+		const info = mountings.get(src);
+		if (!info) return;
+		info.resize.disconnect();
+		if (info.intersection) info.intersection.disconnect();
+		mountings.delete(src);
 	}
-} as Directive;
+} as Directive<Element, (w: number, h: number) => void>;