code · pull · Aug 14, 2025 · Aug 14, 2025
diff --git a/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseRects.css b/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseRects.css
@@ -0,0 +1,15 @@
+.SuspenseRectsContainer {
+  padding: .25rem;
+}
+
+.SuspenseRect {
+  fill: transparent;
+  stroke: var(--color-background-selected);
+  stroke-width: 1px;
+  vector-effect: non-scaling-stroke;
+  paint-order: stroke;
+}
+
+[data-highlighted='true'] > .SuspenseRect {
+  fill: var(--color-selected-tree-highlight-active);
+}
diff --git a/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseRects.js b/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseRects.js
@@ -0,0 +1,200 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import type Store from 'react-devtools-shared/src/devtools/store';
+import type {
+  SuspenseNode,
+  Rect,
+} from 'react-devtools-shared/src/frontend/types';
+
+import * as React from 'react';
+import {useContext} from 'react';
+import {
+  TreeDispatcherContext,
+  TreeStateContext,
+} from '../Components/TreeContext';
+import {StoreContext} from '../context';
+import {useHighlightHostInstance} from '../hooks';
+import styles from './SuspenseRects.css';
+import {SuspenseTreeStateContext} from './SuspenseTreeContext';
+
+function SuspenseRect({rect}: {rect: Rect}): React$Node {
+  return (
+    <rect
+      className={styles.SuspenseRect}
+      x={rect.x}
+      y={rect.y}
+      width={rect.width}
+      height={rect.height}
+    />
+  );
+}
+
+function SuspenseRects({
+  suspenseID,
+}: {
+  suspenseID: SuspenseNode['id'],
+}): React$Node {
+  const dispatch = useContext(TreeDispatcherContext);
+  const store = useContext(StoreContext);
+
+  const {inspectedElementID} = useContext(TreeStateContext);
+
+  const {highlightHostInstance, clearHighlightHostInstance} =
+    useHighlightHostInstance();
+
+  const suspense = store.getSuspenseByID(suspenseID);
+  if (suspense === null) {
+    console.warn(`<Element> Could not find suspense node id ${suspenseID}`);
+    return null;
+  }
+
+  function handleClick(event: SyntheticMouseEvent<>) {
+    if (event.defaultPrevented) {
+      // Already clicked on an inner rect
+      return;
+    }
+    event.preventDefault();
+    dispatch({type: 'SELECT_ELEMENT_BY_ID', payload: suspenseID});
+  }
+
+  function handlePointerOver(event: SyntheticPointerEvent<>) {
+    if (event.defaultPrevented) {
+      // Already hovered an inner rect
+      return;
+    }
+    event.preventDefault();
+    highlightHostInstance(suspenseID);
+  }
+
+  function handlePointerLeave(event: SyntheticPointerEvent<>) {
+    if (event.defaultPrevented) {
+      // Already hovered an inner rect
+      return;
+    }
+    event.preventDefault();
+    clearHighlightHostInstance();
+  }
+
+  // TODO: Use the nearest Suspense boundary
+  const selected = inspectedElementID === suspenseID;
+
+  return (
+    <g
+      data-highlighted={selected}
+      onClick={handleClick}
+      onPointerOver={handlePointerOver}
+      onPointerLeave={handlePointerLeave}>
+      <title>{suspense.name}</title>
+      {suspense.rects !== null &&
+        suspense.rects.map((rect, index) => {
+          return <SuspenseRect key={index} rect={rect} />;
+        })}
+      {suspense.children.map(childID => {
+        return <SuspenseRects key={childID} suspenseID={childID} />;
+      })}
+    </g>
+  );
+}
+
+function getDocumentBoundingRect(
+  store: Store,
+  shells: $ReadOnlyArray<SuspenseNode['id']>,
+): Rect {
+  if (shells.length === 0) {
+    return {x: 0, y: 0, width: 0, height: 0};
+  }
+
+  let minX = Number.POSITIVE_INFINITY;
+  let minY = Number.POSITIVE_INFINITY;
+  let maxX = Number.NEGATIVE_INFINITY;
+  let maxY = Number.NEGATIVE_INFINITY;
+
+  for (let i = 0; i < shells.length; i++) {
+    const shellID = shells[i];
+    const shell = store.getSuspenseByID(shellID);
+    if (shell === null) {
+      continue;
+    }
+
+    const rects = shell.rects;
+    if (rects === null) {
+      continue;
+    }
+    for (let j = 0; j < rects.length; j++) {
+      const rect = rects[j];
+      minX = Math.min(minX, rect.x);
+      minY = Math.min(minY, rect.y);
+      maxX = Math.max(maxX, rect.x + rect.width);
+      maxY = Math.max(maxY, rect.y + rect.height);
+    }
+  }
+
+  if (minX === Number.POSITIVE_INFINITY) {
+    // No rects found, return empty rect
+    return {x: 0, y: 0, width: 0, height: 0};
+  }
+
+  return {
+    x: minX,
+    y: minY,
+    width: maxX - minX,
+    height: maxY - minY,
+  };
+}
+
+function SuspenseRectsShell({
+  shellID,
+}: {
+  shellID: SuspenseNode['id'],
+}): React$Node {
+  const store = useContext(StoreContext);
+  const shell = store.getSuspenseByID(shellID);
+  if (shell === null) {
+    console.warn(`<Element> Could not find suspense node id ${shellID}`);
+    return null;
+  }
+
+  return (
+    <g>
+      {shell.children.map(childID => {
+        return <SuspenseRects key={childID} suspenseID={childID} />;
+      })}
+    </g>
+  );
+}
+
+function SuspenseRectsContainer(): React$Node {
+  const store = useContext(StoreContext);
+  // TODO: This relies on a full re-render of all children when the Suspense tree changes.
+  const {shells} = useContext(SuspenseTreeStateContext);
+
+  const boundingRect = getDocumentBoundingRect(store, shells);
+
+  const width = '100%';
+  const boundingRectWidth = boundingRect.width;
+  const height =
+    (boundingRectWidth === 0 ? 0 : boundingRect.height / boundingRect.width) *
+      100 +
+    '%';
+
+  return (
+    <div className={styles.SuspenseRectsContainer}>
+      <svg
+        style={{width, height}}
+        viewBox={`${boundingRect.x} ${boundingRect.y} ${boundingRect.width} ${boundingRect.height}`}>
+        {shells.map(shellID => {
+          return <SuspenseRectsShell key={shellID} shellID={shellID} />;
+        })}
+      </svg>
+    </div>
+  );
+}
+
+export default SuspenseRectsContainer;
diff --git a/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTab.js b/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTab.js
@@ -19,6 +19,7 @@ import InspectedElementErrorBoundary from '../Components/InspectedElementErrorBo
 import InspectedElement from '../Components/InspectedElement';
 import portaledContent from '../portaledContent';
 import styles from './SuspenseTab.css';
+import SuspenseRects from './SuspenseRects';
 import SuspenseTreeList from './SuspenseTreeList';
 import Button from '../Button';
 
@@ -48,10 +49,6 @@ function SuspenseTimeline() {
   return <div className={styles.Timeline}>timeline</div>;
 }
 
-function SuspenseRects() {
-  return <div>rects</div>;
-}
-
 function ToggleTreeList({
   dispatch,
   state,

diff --git a/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTreeContext.js b/packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTreeContext.js
@@ -17,9 +17,12 @@ import {
   useMemo,
   useReducer,
 } from 'react';
+import type {SuspenseNode} from '../../../frontend/types';
 import {StoreContext} from '../context';
 
-export type SuspenseTreeState = {};
+export type SuspenseTreeState = {
+  shells: $ReadOnlyArray<SuspenseNode['id']>,
+};
 
 type ACTION_HANDLE_SUSPENSE_TREE_MUTATION = {
   type: 'HANDLE_SUSPENSE_TREE_MUTATION',
@@ -56,15 +59,18 @@ function SuspenseTreeContextController({children}: Props): React.Node {
         const {type} = action;
         switch (type) {
           case 'HANDLE_SUSPENSE_TREE_MUTATION':
-            return {...state};
+            return {...state, shells: store.roots};
           default:
             throw new Error(`Unrecognized action "${type}"`);
         }
       },
     [],
   );
 
-  const [state, dispatch] = useReducer(reducer, {});
+  const initialState: SuspenseTreeState = {
+    shells: store.roots,
+  };
+  const [state, dispatch] = useReducer(reducer, initialState);
   const transitionDispatch = useMemo(
     () => (action: SuspenseTreeAction) =>
       startTransition(() => {