[DevTools] Highlight the rect when the corresponding timeline bean is hovered

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseRects.css

@@ -8,8 +8,8 @@
   background-color: color-mix(in srgb, var(--color-transition) 5%, transparent);
 }
 
-.SuspenseRectsContainer:hover:not(:has(.SuspenseRectsBoundary:hover))[data-highlighted='false'] {
-  outline-width: 1px;
+.SuspenseRectsContainer[data-hovered='true'] {
+  background-color: color-mix(in srgb, var(--color-transition) 15%, transparent);
 }
 
 .SuspenseRectsContainer[data-highlighted='true'] {
@@ -65,7 +65,7 @@
 }
 
 /* highlight this boundary */
-.SuspenseRectsBoundary:hover:not(:has(.SuspenseRectsBoundary:hover)) > .SuspenseRectsRect {
+.SuspenseRectsBoundary[data-hovered='true'] > .SuspenseRectsRect {
   background-color: color-mix(in srgb, var(--color-background) 50%, var(--color-suspense) 50%);
   transition: background-color 0.2s ease-out;
 }

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseRects.js

@@ -37,6 +37,7 @@ function ScaledRect({
   visible,
   suspended,
   selected,
+  hovered,
   adjust,
   ...props
 }: {
@@ -45,6 +46,7 @@ function ScaledRect({
   visible: boolean,
   suspended: boolean,
   selected?: boolean,
+  hovered?: boolean,
   adjust?: boolean,
   ...
 }): React$Node {
@@ -61,6 +63,7 @@ function ScaledRect({
       data-visible={visible}
       data-suspended={suspended}
       data-selected={selected}
+      data-hovered={hovered}
       style={{
         // Shrink one pixel so that the bottom outline will line up with the top outline of the next one.
         width: adjust ? 'calc(' + width + ' - 1px)' : width,
@@ -80,7 +83,9 @@ function SuspenseRects({
   const store = useContext(StoreContext);
   const treeDispatch = useContext(TreeDispatcherContext);
   const suspenseTreeDispatch = useContext(SuspenseTreeDispatcherContext);
-  const {uniqueSuspendersOnly} = useContext(SuspenseTreeStateContext);
+  const {uniqueSuspendersOnly, timeline, hoveredTimelineIndex} = useContext(
+    SuspenseTreeStateContext,
+  );
 
   const {inspectedElementID} = useContext(TreeStateContext);
 
@@ -148,6 +153,9 @@ function SuspenseRects({
   // TODO: Use the nearest Suspense boundary
   const selected = inspectedElementID === suspenseID;
 
+  const hovered =
+    hoveredTimelineIndex > -1 && timeline[hoveredTimelineIndex] === suspenseID;
+
   const boundingBox = getBoundingBox(suspense.rects);
 
   return (
@@ -156,7 +164,8 @@ function SuspenseRects({
       className={styles.SuspenseRectsBoundary}
       visible={visible}
       selected={selected}
-      suspended={suspense.isSuspended}>
+      suspended={suspense.isSuspended}
+      hovered={hovered}>
       <ViewBox.Provider value={boundingBox}>
         {visible &&
           suspense.rects !== null &&
@@ -317,7 +326,7 @@ function SuspenseRectsContainer(): React$Node {
   const treeDispatch = useContext(TreeDispatcherContext);
   const suspenseTreeDispatch = useContext(SuspenseTreeDispatcherContext);
   // TODO: This relies on a full re-render of all children when the Suspense tree changes.
-  const {roots} = useContext(SuspenseTreeStateContext);
+  const {roots, hoveredTimelineIndex} = useContext(SuspenseTreeStateContext);
 
   // TODO: bbox does not consider uniqueSuspendersOnly filter
   const boundingBox = getDocumentBoundingRect(store, roots);
@@ -361,13 +370,15 @@ function SuspenseRectsContainer(): React$Node {
   }
 
   const isRootSelected = roots.includes(inspectedElementID);
+  const isRootHovered = hoveredTimelineIndex === 0;
 
   return (
     <div
       className={styles.SuspenseRectsContainer}
       onClick={handleClick}
       onDoubleClick={handleDoubleClick}
-      data-highlighted={isRootSelected}>
+      data-highlighted={isRootSelected}
+      data-hovered={isRootHovered}>
       <ViewBox.Provider value={boundingBox}>
         <div
           className={styles.SuspenseRectsViewBox}

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseScrubber.css

@@ -54,8 +54,7 @@
   background: var(--color-transition);
 }
 
-.SuspenseScrubberStepHighlight > .SuspenseScrubberBead,
-.SuspenseScrubberStep:hover > .SuspenseScrubberBead {
+.SuspenseScrubberStepHighlight > .SuspenseScrubberBead {
   height: 0.75rem;
   transition: all 0.3s ease-out;
 }

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTimeline.js

@@ -53,10 +53,19 @@ function SuspenseTimelineInput() {
     switchSuspenseNode(timelineIndex);
   }
 
-  function handleHoverSegment(hoveredValue: number) {
-    // TODO: Consider highlighting the rect instead.
+  function handleHoverSegment(hoveredIndex: number) {
+    const nextSelectedSuspenseID = timeline[hoveredIndex];
+    suspenseTreeDispatch({
+      type: 'HOVER_TIMELINE_FOR_ID',
+      payload: nextSelectedSuspenseID,
+    });
+  }
+  function handleUnhoverSegment() {
+    suspenseTreeDispatch({
+      type: 'HOVER_TIMELINE_FOR_ID',
+      payload: -1,
+    });
   }
-  function handleUnhoverSegment() {}
 
   function skipPrevious() {
     const nextSelectedSuspenseID = timeline[timelineIndex - 1];