feat: delay hiding the overlay

src/hoverifier.test.ts

@@ -741,6 +741,80 @@ describe('Hoverifier', () => {
         }
     })
 
+    it('keeps the overlay open when the mouse briefly moves over another token on the way to the overlay', () => {
+        for (const codeView of testcases) {
+            const scheduler = new TestScheduler((a, b) => chai.assert.deepEqual(a, b))
+
+            const hover = {}
+
+            scheduler.run(({ cold, expectObservable }) => {
+                const hoverOverlayElement = document.createElement('div')
+
+                const hoverifier = createHoverifier({
+                    closeButtonClicks: new Observable<MouseEvent>(),
+                    hoverOverlayElements: of(hoverOverlayElement),
+                    hoverOverlayRerenders: EMPTY,
+                    getHover: createStubHoverProvider(hover),
+                    getDocumentHighlights: createStubDocumentHighlightProvider(),
+                    getActions: () => of(null),
+                    pinningEnabled: true,
+                })
+
+                const positionJumps = new Subject<PositionJump>()
+
+                const positionEvents = of(codeView.codeView).pipe(findPositionsFromEvents({ domFunctions: codeView }))
+
+                const subscriptions = new Subscription()
+
+                subscriptions.add(hoverifier)
+                subscriptions.add(
+                    hoverifier.hoverify({
+                        dom: codeView,
+                        positionEvents,
+                        positionJumps,
+                        resolveContext: () => codeView.revSpec,
+                    })
+                )
+
+                const hoverAndDefinitionUpdates = hoverifier.hoverStateUpdates.pipe(
+                    filter(propertyIsDefined('hoverOverlayProps')),
+                    map(({ hoverOverlayProps }) => hoverOverlayProps.hoveredToken?.character),
+                    distinctUntilChanged(isEqual)
+                )
+
+                const outputDiagram = `${TOOLTIP_DISPLAY_DELAY + MOUSEOVER_DELAY + 1}ms a`
+
+                const outputValues: { [key: string]: number } = {
+                    a: 6,
+                }
+
+                cold(`a b ${TOOLTIP_DISPLAY_DELAY}ms c d 1ms e`, {
+                    a: ['mouseover', 6],
+                    b: ['mousemove', 6],
+                    c: ['mouseover', 19],
+                    d: ['mousemove', 19],
+                    e: ['mouseover', 'overlay'],
+                } as Record<string, [SupportedMouseEvent, number | 'overlay']>).subscribe(([eventType, value]) => {
+                    if (value === 'overlay') {
+                        hoverOverlayElement.dispatchEvent(
+                            new MouseEvent(eventType, {
+                                bubbles: true, // Must be true so that React can see it.
+                            })
+                        )
+                    } else {
+                        dispatchMouseEventAtPositionImpure(eventType, codeView, {
+                            line: 24,
+                            character: value,
+                        })
+                    }
+                })
+
+                expectObservable(hoverAndDefinitionUpdates).toBe(outputDiagram, outputValues)
+            })
+            break
+        }
+    })
+
     it('dedupes mouseover and mousemove event on same token', () => {
         for (const codeView of testcases) {
             const scheduler = new TestScheduler((a, b) => chai.assert.deepEqual(a, b))

src/hoverifier.ts

@@ -15,6 +15,8 @@ import {
     SubscribableOrPromise,
     Subscription,
     zip,
+    race,
+    MonoTypeOperatorFunction,
 } from 'rxjs'
 import {
     catchError,
@@ -30,6 +32,8 @@ import {
     takeUntil,
     withLatestFrom,
     mergeMap,
+    delay,
+    startWith,
 } from 'rxjs/operators'
 import { Key } from 'ts-key-enum'
 import { asError, ErrorLike, isErrorLike } from './errors'
@@ -406,6 +410,7 @@ export type ContextResolver<C extends object> = (hoveredToken: HoveredToken) =>
  */
 export function createHoverifier<C extends object, D, A>({
     closeButtonClicks,
+    hoverOverlayElements,
     hoverOverlayRerenders,
     getHover,
     getDocumentHighlights,
@@ -433,11 +438,28 @@ export function createHoverifier<C extends object, D, A>({
     // These Subjects aggregate all events from all hoverified code views
     const allPositionsFromEvents = new Subject<MouseEventTrigger>()
 
+    // This keeps the overlay open while the mouse moves over another token on the way to the overlay
+    const suppressWhileOverlayShown = <T>(): MonoTypeOperatorFunction<T> => o =>
+        o.pipe(
+            withLatestFrom(from(hoverOverlayElements).pipe(startWith(null))),
+            switchMap(([t, overlayElement]) =>
+                overlayElement === null
+                    ? of(t)
+                    : race(
+                          fromEvent(overlayElement, 'mouseover').pipe(mapTo('suppress')),
+                          of('emit').pipe(delay(MOUSEOVER_DELAY))
+                      ).pipe(
+                          filter(action => action === 'emit'),
+                          mapTo(t)
+                      )
+            )
+        )
+
     const isEventType = <T extends SupportedMouseEvent>(type: T) => (
         event: MouseEventTrigger
     ): event is MouseEventTrigger & { eventType: T } => event.eventType === type
-    const allCodeMouseMoves = allPositionsFromEvents.pipe(filter(isEventType('mousemove')))
-    const allCodeMouseOvers = allPositionsFromEvents.pipe(filter(isEventType('mouseover')))
+    const allCodeMouseMoves = allPositionsFromEvents.pipe(filter(isEventType('mousemove')), suppressWhileOverlayShown())
+    const allCodeMouseOvers = allPositionsFromEvents.pipe(filter(isEventType('mouseover')), suppressWhileOverlayShown())
     const allCodeClicks = allPositionsFromEvents.pipe(filter(isEventType('click')))
 
     const allPositionJumps = new Subject<PositionJump & EventOptions<C>>()