From b2d8bb108811af92e1563a5829355b1698da6628 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cchrisshank=E2=80=9D?= <chris.shank.23@gmail.com>
Date: Mon, 16 Dec 2024 15:04:52 -0800
Subject: [PATCH] observer iframe rects

---
 demo/cross-iframe-sticky-html-arrow.html |   4 +-
 demo/cross-iframe-xanadu-links.html      |   2 +
 src/common/client-rect-observer.ts       |   4 -
 src/common/folk-observer.ts              | 172 ++++++++++++++++++++++-
 src/common/iframe-script.ts              |  83 +----------
 src/folk-base-connection.ts              |  22 ++-
 6 files changed, 191 insertions(+), 96 deletions(-)

diff --git a/demo/cross-iframe-sticky-html-arrow.html b/demo/cross-iframe-sticky-html-arrow.html
index 158d1eb..2237bb2 100644
--- a/demo/cross-iframe-sticky-html-arrow.html
+++ b/demo/cross-iframe-sticky-html-arrow.html
@@ -23,6 +23,8 @@
       iframe {
         width: 100%;
         height: 100%;
+        /* margins cause infinite resize loops */
+        box-sizing: border-box;
       }
     </style>
   </head>
@@ -34,7 +36,7 @@
       <iframe id="frame2" src="./sticky-html-arrow.html"></iframe>
     </folk-shape>
 
-    <folk-rope source="#frame1 >>> #box1" target="#frame2 >>> #box1"></folk-rope>
+    <folk-rope source="#frame1 >>> #box1" target="#frame2 >>> #box2"></folk-rope>
 
     <script type="module">
       import '../src/standalone/folk-shape.ts';
diff --git a/demo/cross-iframe-xanadu-links.html b/demo/cross-iframe-xanadu-links.html
index 45a0074..3c99a33 100644
--- a/demo/cross-iframe-xanadu-links.html
+++ b/demo/cross-iframe-xanadu-links.html
@@ -34,6 +34,8 @@
         height: 100%;
         position: absolute;
         background-color: white;
+        /* margins cause infinite resize loops */
+        box-sizing: border-box;
 
         &:nth-child(1) {
           left: 50px;
diff --git a/src/common/client-rect-observer.ts b/src/common/client-rect-observer.ts
index 0e51bde..6891408 100644
--- a/src/common/client-rect-observer.ts
+++ b/src/common/client-rect-observer.ts
@@ -171,12 +171,8 @@ export class ClientRectObserver {
   }
 
   takeRecords(): ClientRectObserverEntry[] {
-    if (this.#rafId === 0) return [];
-
     const entries = this.#entries;
     this.#entries = [];
-    cancelAnimationFrame(this.#rafId);
-    this.#rafId = 0;
     return entries;
   }
 
diff --git a/src/common/folk-observer.ts b/src/common/folk-observer.ts
index e81aa39..e71cd90 100644
--- a/src/common/folk-observer.ts
+++ b/src/common/folk-observer.ts
@@ -4,6 +4,130 @@ import { TransformEvent } from './TransformEvent';
 
 export type ClientRectObserverEntryCallback = (entry: ClientRectObserverEntry) => void;
 
+export type FolkObserverOptions = {
+  iframeSelector?: string;
+};
+
+interface IframeChild {
+  rect: DOMRectReadOnly | null;
+  callbacks: Set<ClientRectObserverEntryCallback>;
+}
+
+type PostMessageSendEvent =
+  | { type: 'folk-observe-element'; selector: string }
+  | { type: 'folk-unobserve-element'; selector: string };
+
+class IframeObserver {
+  #iframe;
+  #observer;
+  #iframeRect!: DOMRectReadOnly;
+  #iframeChildren = new Map<string, IframeChild>();
+  #isDisposed = false;
+
+  get isDisposed() {
+    return this.#isDisposed;
+  }
+
+  constructor(iframe: HTMLIFrameElement, observer: FolkObserver) {
+    this.#iframe = iframe;
+    this.#observer = observer;
+
+    observer.observe(iframe, this.#iframeCallback);
+    window.addEventListener('message', this.#onPostmessage);
+  }
+
+  observeChild(selector: string, callback: ClientRectObserverEntryCallback) {
+    let child = this.#iframeChildren.get(selector);
+
+    if (child === undefined) {
+      child = {
+        callbacks: new Set(),
+        rect: null,
+      };
+
+      this.#iframeChildren.set(selector, child);
+
+      this.#postMessage({ type: 'folk-observe-element', selector });
+    }
+
+    child.callbacks.add(callback);
+  }
+
+  unobserveChild(selector: string, callback: ClientRectObserverEntryCallback) {
+    let child = this.#iframeChildren.get(selector);
+
+    if (child === undefined) return;
+
+    child.callbacks.delete(callback);
+
+    if (child.callbacks.size === 0) {
+      this.#iframeChildren.delete(selector);
+      this.#postMessage({ type: 'folk-unobserve-element', selector });
+    }
+
+    if (this.#iframeChildren.size === 0) {
+      this.#observer.unobserve(this.#iframe, this.#iframeCallback);
+      window.removeEventListener('message', this.#onPostmessage);
+      this.#isDisposed = true;
+    }
+  }
+
+  #iframeCallback = (entry: ClientRectObserverEntry) => {
+    this.#iframeRect = entry.contentRect;
+
+    for (const selector of this.#iframeChildren.keys()) {
+      this.#updatedChildRect(selector);
+    }
+  };
+
+  #onPostmessage = (event: MessageEvent) => {
+    if (event.source !== this.#iframe.contentWindow) return;
+
+    switch (event.data.type) {
+      case 'folk-iframe-ready': {
+        for (const selector of this.#iframeChildren.keys()) {
+          this.#postMessage({ type: 'folk-observe-element', selector });
+        }
+        return;
+      }
+      case 'folk-element-change': {
+        this.#updatedChildRect(event.data.selector, event.data.contentRect);
+        return;
+      }
+    }
+  };
+
+  #updatedChildRect(selector: string, rect?: DOMRectReadOnly) {
+    const child = this.#iframeChildren.get(selector);
+
+    if (child === undefined) return;
+
+    if (rect) {
+      child.rect = rect;
+    }
+
+    if (child.rect === null) return;
+
+    const contentRect = DOMRectReadOnly.fromRect({
+      x: this.#iframeRect.x + child.rect.x,
+      y: this.#iframeRect.y + child.rect.y,
+      height: child.rect.height,
+      width: child.rect.width,
+    });
+
+    child.callbacks.forEach((callback) =>
+      callback({
+        target: this.#iframe,
+        contentRect,
+      })
+    );
+  }
+
+  #postMessage(event: PostMessageSendEvent) {
+    this.#iframe.contentWindow?.postMessage(event);
+  }
+}
+
 export class FolkObserver {
   static #instance: FolkObserver | null = null;
 
@@ -16,6 +140,7 @@ export class FolkObserver {
   }
 
   #elementMap = new WeakMap<Element, Set<ClientRectObserverEntryCallback>>();
+  #iframeMap = new WeakMap<HTMLIFrameElement, IframeObserver>();
 
   #vo = new ClientRectObserver((entries) => {
     for (const entry of entries) {
@@ -35,29 +160,62 @@ export class FolkObserver {
     this.#updateTarget({ target: event.target as HTMLElement, contentRect: event.current });
   };
 
-  observe(target: Element, callback: ClientRectObserverEntryCallback): void {
-    let callbacks = this.#elementMap.get(target);
+  observe(
+    target: Element,
+    callback: ClientRectObserverEntryCallback,
+    { iframeSelector }: FolkObserverOptions = {}
+  ): void {
+    if (target instanceof HTMLIFrameElement && iframeSelector) {
+      let iframeObserver = this.#iframeMap.get(target);
 
-    const isFolkShape = target instanceof FolkShape;
+      if (iframeObserver === undefined) {
+        iframeObserver = new IframeObserver(target, this);
+        this.#iframeMap.set(target, iframeObserver);
+      }
+
+      iframeObserver.observeChild(iframeSelector, callback);
+
+      return;
+    }
+
+    let callbacks = this.#elementMap.get(target);
 
     if (callbacks === undefined) {
       this.#elementMap.set(target, (callbacks = new Set()));
 
-      if (isFolkShape) {
+      if (target instanceof FolkShape) {
         target.addEventListener('transform', this.#onTransform);
         callback({ target, contentRect: target.getTransformDOMRect() });
       } else {
         this.#vo.observe(target);
       }
     } else {
-      const contentRect = isFolkShape ? target.getTransformDOMRect() : target.getBoundingClientRect();
+      const contentRect = target instanceof FolkShape ? target.getTransformDOMRect() : target.getBoundingClientRect();
       callback({ target, contentRect });
     }
 
     callbacks.add(callback);
   }
 
-  unobserve(target: Element, callback: ClientRectObserverEntryCallback): void {
+  unobserve(
+    target: Element,
+    callback: ClientRectObserverEntryCallback,
+    { iframeSelector }: FolkObserverOptions = {}
+  ): void {
+    if (target instanceof HTMLIFrameElement && iframeSelector) {
+      let iframeObserver = this.#iframeMap.get(target);
+
+      if (iframeObserver === undefined) return;
+
+      iframeObserver.unobserveChild(iframeSelector, callback);
+
+      if (iframeObserver.isDisposed) {
+        this.#iframeMap.delete(target);
+      }
+
+      return;
+    }
+
     let callbacks = this.#elementMap.get(target);
 
     if (callbacks === undefined) return;
@@ -75,6 +233,6 @@ export class FolkObserver {
   }
 }
 
-export function parseCSSSelector(selector: string): string[] {
+export function parseDeepCSSSelector(selector: string): string[] {
   return selector.split('>>>').map((s) => s.trim());
 }
diff --git a/src/common/iframe-script.ts b/src/common/iframe-script.ts
index 6082402..e0385ac 100644
--- a/src/common/iframe-script.ts
+++ b/src/common/iframe-script.ts
@@ -1,52 +1,7 @@
-import { FolkShape } from '../folk-shape.ts';
-import { ClientRectObserverManager, ClientRectObserverEntry } from './client-rect-observer.ts';
-import { TransformEvent } from './TransformEvent.ts';
+import { ClientRectObserverEntry } from './client-rect-observer.ts';
+import { FolkObserver } from './folk-observer.ts';
 
-const clientRectObserver = new ClientRectObserverManager();
-
-interface ObservedElementEntry {
-  selector: string;
-  element: Element;
-  count: number;
-}
-
-class ObservedElements {
-  #elements: ObservedElementEntry[] = [];
-
-  observe(selector: string) {
-    let entry = this.#elements.find((e) => e.selector === selector);
-
-    if (entry === undefined) {
-      entry = { selector, element: document.querySelector(selector)!, count: 0 };
-      this.#elements.push(entry);
-    }
-
-    entry.count += 1;
-
-    return entry.element;
-  }
-
-  unobserve(selector: string) {
-    const entryIndex = this.#elements.findIndex((e) => e.selector === selector);
-    const entry = this.#elements[entryIndex];
-
-    if (entry === undefined) return;
-
-    entry.count -= 1;
-
-    if (entry.count === 0) {
-      this.#elements.splice(entryIndex, 1);
-    }
-  }
-
-  getElement(selector: string) {
-    return this.#elements.find((e) => e.selector === selector)?.element;
-  }
-
-  getSelector(element: Element) {
-    return this.#elements.find((e) => e.element === element)?.selector;
-  }
-}
+const folkObserver = new FolkObserver();
 
 // If this page is framed in then mock inject the following post message script
 if (window.parent !== window) {
@@ -58,15 +13,7 @@ if (window.parent !== window) {
     window.parent.postMessage({
       type: 'folk-element-change',
       selector: observedSelectors.get(entry.target),
-      boundingBox: entry.contentRect,
-    });
-  }
-
-  function onGeometryChange(event: TransformEvent) {
-    window.parent.postMessage({
-      type: 'folk-element-change',
-      selector: observedSelectors.get(event.target),
-      boundingBox: (event.target as FolkShape)?.getTransformDOMRect(),
+      contentRect: entry.contentRect.toJSON(),
     });
   }
 
@@ -81,17 +28,7 @@ if (window.parent !== window) {
         observedElements.set(selector, element);
         observedSelectors.set(element, selector);
 
-        if (element instanceof FolkShape) {
-          element.addEventListener('transform', onGeometryChange);
-
-          window.parent.postMessage({
-            type: 'folk-element-change',
-            selector: selector,
-            boundingBox: element.getTransformDOMRect(),
-          });
-        } else {
-          clientRectObserver.observe(element, boundingBoxCallback);
-        }
+        folkObserver.observe(element, boundingBoxCallback);
         return;
       }
       case 'folk-unobserve-element': {
@@ -100,15 +37,7 @@ if (window.parent !== window) {
 
         if (element === undefined) return;
 
-        if (element instanceof FolkShape) {
-          element.removeEventListener('transform', onGeometryChange);
-          observedElements.delete(selector);
-          observedSelectors.delete(element);
-        } else {
-          clientRectObserver.unobserve(element, boundingBoxCallback);
-        }
-
-        return;
+        folkObserver.unobserve(element, boundingBoxCallback);
       }
     }
   });
diff --git a/src/folk-base-connection.ts b/src/folk-base-connection.ts
index 282f53e..8b795b3 100644
--- a/src/folk-base-connection.ts
+++ b/src/folk-base-connection.ts
@@ -1,6 +1,6 @@
 import { parseVertex } from './common/utils.ts';
 import { ClientRectObserverEntry } from './common/client-rect-observer.ts';
-import { FolkObserver } from './common/folk-observer.ts';
+import { FolkObserver, parseDeepCSSSelector } from './common/folk-observer.ts';
 import { FolkElement } from './common/folk-element.ts';
 import { property, state } from '@lit/reactive-element/decorators.js';
 import { css, CSSResultGroup, PropertyValues } from '@lit/reactive-element';
@@ -19,12 +19,16 @@ export class FolkBaseConnection extends FolkElement {
 
   @property({ type: String, reflect: true }) source?: string;
 
+  #sourceIframeSelector: string | undefined = undefined;
+
   @state() sourceElement: Element | null = null;
 
   @state() sourceRect: DOMRectReadOnly | null = null;
 
   @property({ type: String, reflect: true }) target?: string;
 
+  #targetIframeSelector: string | undefined = undefined;
+
   @state() targetRect: DOMRectReadOnly | null = null;
 
   @state() targetElement: Element | null = null;
@@ -48,7 +52,9 @@ export class FolkBaseConnection extends FolkElement {
       if (vertex) {
         this.sourceRect = DOMRectReadOnly.fromRect(vertex);
       } else {
-        this.sourceElement = document.querySelector(this.source);
+        const [selector, iframeSelector] = parseDeepCSSSelector(this.source);
+        this.#sourceIframeSelector = iframeSelector;
+        this.sourceElement = document.querySelector(selector);
       }
     }
 
@@ -56,7 +62,7 @@ export class FolkBaseConnection extends FolkElement {
       if (this.sourceElement === null) {
         this.sourceRect = null;
       } else {
-        folkObserver.observe(this.sourceElement, this.#sourceCallback);
+        folkObserver.observe(this.sourceElement, this.#sourceCallback, { iframeSelector: this.#sourceIframeSelector });
       }
     }
 
@@ -70,7 +76,9 @@ export class FolkBaseConnection extends FolkElement {
       if (vertex) {
         this.targetRect = DOMRectReadOnly.fromRect(vertex);
       } else {
-        this.targetElement = document.querySelector(this.target);
+        const [selector, iframeSelector] = parseDeepCSSSelector(this.target);
+        this.#targetIframeSelector = iframeSelector;
+        this.targetElement = document.querySelector(selector);
       }
     }
 
@@ -78,7 +86,7 @@ export class FolkBaseConnection extends FolkElement {
       if (this.targetElement === null) {
         this.targetRect = null;
       } else {
-        folkObserver.observe(this.targetElement, this.#targetCallback);
+        folkObserver.observe(this.targetElement, this.#targetCallback, { iframeSelector: this.#targetIframeSelector });
       }
     }
   }
@@ -90,7 +98,7 @@ export class FolkBaseConnection extends FolkElement {
   #unobserveSource() {
     if (this.sourceElement === null) return;
 
-    folkObserver.unobserve(this.sourceElement, this.#sourceCallback);
+    folkObserver.unobserve(this.sourceElement, this.#sourceCallback, { iframeSelector: this.#sourceIframeSelector });
   }
 
   #targetCallback = (entry: ClientRectObserverEntry) => {
@@ -99,6 +107,6 @@ export class FolkBaseConnection extends FolkElement {
 
   #unobserveTarget() {
     if (this.targetElement === null) return;
-    folkObserver.unobserve(this.targetElement, this.#targetCallback);
+    folkObserver.unobserve(this.targetElement, this.#targetCallback, { iframeSelector: this.#targetIframeSelector });
   }
 }