Refactor infinite scroll

src/app/grid/page.tsx

@@ -35,7 +35,7 @@ export default async function GridPage() {
     photos.length > 0
       ? <SiteGrid
         contentMain={<div className="space-y-0.5 sm:space-y-1">
-          <PhotoGrid {...{ photos, photoPriority: true }} />
+          <PhotoGrid {...{ photos }} />
           {photos.length >= INFINITE_SCROLL_MULTIPLE_GRID &&
             <InfinitePhotoScroll
               type='grid'

src/components/SiteGrid.tsx

@@ -1,12 +1,15 @@
 import { clsx } from 'clsx/lite';
+import { RefObject } from 'react';
 
 export default function SiteGrid({
+  containerRef,
   className,
   contentMain,
   contentSide,
   sideFirstOnMobile,
   sideHiddenOnMobile,
 }: {
+  containerRef?: RefObject<HTMLDivElement>
   className?: string
   contentMain: JSX.Element
   contentSide?: JSX.Element
@@ -14,14 +17,17 @@ export default function SiteGrid({
   sideHiddenOnMobile?: boolean
 }) {
   return (
-    <div className={clsx(
-      className,
-      'grid',
-      'grid-cols-1 md:grid-cols-12',
-      'gap-x-4 lg:gap-x-6',
-      'gap-y-4',
-      'max-w-7xl',
-    )}>
+    <div
+      ref={containerRef}
+      className={clsx(
+        className,
+        'grid',
+        'grid-cols-1 md:grid-cols-12',
+        'gap-x-4 lg:gap-x-6',
+        'gap-y-4',
+        'max-w-7xl',
+      )}
+    >
       <div className={clsx(
         'col-span-1 md:col-span-9',
         sideFirstOnMobile && 'order-2 md:order-none',

src/photo/InfinitePhotoScroll.tsx

@@ -1,11 +1,9 @@
 'use client';
 
-import { preload } from 'swr';
 import useSwrInfinite from 'swr/infinite';
 import PhotosLarge from '@/photo/PhotosLarge';
 import {
   useCallback,
-  useEffect,
   useMemo,
   useRef,
 } from 'react';
@@ -26,14 +24,10 @@ export default function InfinitePhotoScroll({
   type = 'full-frame',
   initialOffset = 0,
   itemsPerPage = 12,
-  prefetch = true,
-  triggerOnView = true,
 }: {
   type?: 'full-frame' | 'grid'
   initialOffset?: number
   itemsPerPage?: number
-  prefetch?: boolean
-  triggerOnView?: boolean
   debug?: boolean
 }) {
   const { swrTimestamp, isUserSignedIn } = useAppState();
@@ -46,20 +40,21 @@ export default function InfinitePhotoScroll({
       : [key, size]
     , [key]);
 
-  const fetcher = useCallback(([_key, size]: [string, number]) =>
-    getPhotosAction(
+  const fetcher = useCallback(([_key, size]: [string, number]) => {
+    console.log('Fetching', size);
+    return getPhotosAction(
       initialOffset + size * itemsPerPage,
       itemsPerPage,
-    )
-  , [initialOffset, itemsPerPage]);
+    );
+  }, [initialOffset, itemsPerPage]);
 
-  const { data, isLoading, isValidating, error, mutate, size, setSize } =
+  const { data, isLoading, isValidating, error, mutate, setSize } =
     useSwrInfinite<Photo[]>(
       keyGenerator,
       fetcher,
       {
-        revalidateFirstPage: Boolean(isUserSignedIn),
-        revalidateOnMount: Boolean(isUserSignedIn),
+        initialSize: 2,
+        revalidateFirstPage: false,
         revalidateOnFocus: Boolean(isUserSignedIn),
         revalidateOnReconnect: Boolean(isUserSignedIn),
       },
@@ -73,46 +68,11 @@ export default function InfinitePhotoScroll({
     data && data[data.length - 1]?.length < itemsPerPage
   , [data, itemsPerPage]);
 
-  useEffect(() => {
-    if (prefetch && !isFinished) {
-      preload([key, (size ?? 0) + 1], fetcher);
-    }
-  }, [prefetch, isFinished, key, size, fetcher]);
-
   const advance = useCallback(() => {
     if (!isFinished && !isLoadingOrValidating) {
       setSize(size => size + 1);
     }
-  }, [isFinished, setSize, isLoadingOrValidating]);
-
-  useEffect(() => {
-    // Only add observer if button is rendered
-    if (buttonContainerRef.current) {
-      const observer = new IntersectionObserver(e => {
-        if (triggerOnView && e[0].isIntersecting) {
-          advance();
-        }
-      }, {
-        root: null,
-        threshold: 0,
-      });
-      observer.observe(buttonContainerRef.current);
-      return () => observer.disconnect();
-    }
-  }, [triggerOnView, advance]);
-
-  // Poll for button getting stuck
-  useEffect(() => {
-    if (triggerOnView && !isFinished && !isLoadingOrValidating) {
-      const interval = setInterval(() => {
-        const rect = buttonContainerRef.current?.getBoundingClientRect();
-        if (rect && rect.top <= window.innerHeight) {
-          advance();
-        }
-      }, 1000);
-      return () => clearInterval(interval);
-    }
-  }, [advance, isFinished, isLoadingOrValidating, triggerOnView]);
+  }, [isFinished, isLoadingOrValidating, setSize]);
 
   const photos = useMemo(() => (data ?? [])?.flat(), [data]);
 
@@ -128,11 +88,7 @@ export default function InfinitePhotoScroll({
   } as any), [data, mutate]);
 
   const renderMoreButton = () =>
-    <div
-      ref={buttonContainerRef}
-      // Make button bounding visible earlier
-      className="-translate-y-32 pt-32 -mb-32"
-    >
+    <div ref={buttonContainerRef}>
       <button
         onClick={() => error ? mutate() : advance()}
         disabled={isLoading || isValidating}
@@ -152,8 +108,15 @@ export default function InfinitePhotoScroll({
   return (
     <div className="space-y-4">
       {type === 'full-frame'
-        ? <PhotosLarge {...{ photos, revalidatePhoto }} />
-        : <PhotoGrid {...{ photos }} />}
+        ? <PhotosLarge {...{
+          photos,
+          revalidatePhoto,
+          onLastPhotoVisible: advance,
+        }} />
+        : <PhotoGrid {...{
+          photos,
+          onLastPhotoVisible: advance,
+        }} />}
       {!isFinished && (type === 'full-frame'
         ? <SiteGrid contentMain={renderMoreButton()} />
         : renderMoreButton())}

src/photo/PhotoGrid.tsx

@@ -19,6 +19,7 @@ export default function PhotoGrid({
   staggerOnFirstLoadOnly = true,
   additionalTile,
   small,
+  onLastPhotoVisible,
 }: {
   photos: Photo[]
   selectedPhoto?: Photo
@@ -33,6 +34,7 @@ export default function PhotoGrid({
   showMorePath?: string
   additionalTile?: JSX.Element
   small?: boolean
+  onLastPhotoVisible?: () => void
 }) {
   return (
     <AnimateItems
@@ -51,7 +53,7 @@ export default function PhotoGrid({
       distanceOffset={40}
       animateOnFirstLoadOnly={animateOnFirstLoadOnly}
       staggerOnFirstLoadOnly={staggerOnFirstLoadOnly}
-      items={photos.map(photo =>
+      items={photos.map((photo, index) =>
         <div
           key={photo.id}
           className={GRID_ASPECT_RATIO !== 0
@@ -70,6 +72,9 @@ export default function PhotoGrid({
             simulation,
             selected: photo.id === selectedPhoto?.id,
             priority: photoPriority,
+            onVisible: index === photos.length - 1
+              ? onLastPhotoVisible
+              : undefined,
           }} />
         </div>).concat(additionalTile ?? [])}
       itemKeys={photos.map(photo => photo.id)

src/photo/PhotoLarge.tsx

@@ -22,6 +22,7 @@ import PhotoLink from './PhotoLink';
 import { SHOULD_PREFETCH_ALL_LINKS } from '@/site/config';
 import AdminPhotoMenuClient from '@/admin/AdminPhotoMenuClient';
 import { RevalidatePhoto } from './InfinitePhotoScroll';
+import { useEffect, useRef } from 'react';
 
 export default function PhotoLarge({
   photo,
@@ -36,6 +37,7 @@ export default function PhotoLarge({
   shouldShareCamera,
   shouldShareSimulation,
   shouldScrollOnShare,
+  onVisible,
 }: {
   photo: Photo
   primaryTag?: string
@@ -49,7 +51,10 @@ export default function PhotoLarge({
   shouldShareCamera?: boolean
   shouldShareSimulation?: boolean
   shouldScrollOnShare?: boolean
+  onVisible?: () => void
 }) {
+  const ref = useRef<HTMLDivElement>(null);
+
   const tags = sortTags(photo.tags, primaryTag);
 
   const camera = cameraFromPhoto(photo);
@@ -58,8 +63,24 @@ export default function PhotoLarge({
   const showTagsContent = tags.length > 0;
   const showExifContent = shouldShowExifDataForPhoto(photo);
 
+  useEffect(() => {
+    if (onVisible && ref.current) {
+      const observer = new IntersectionObserver(e => {
+        if (e[0].isIntersecting) {
+          onVisible();
+        }
+      }, {
+        root: null,
+        threshold: 0,
+      });
+      observer.observe(ref.current);
+      return () => observer.disconnect();
+    }
+  }, [onVisible]);
+
   return (
     <SiteGrid
+      containerRef={ref}
       contentMain={
         <Link
           href={pathForPhoto(photo)}

src/photo/PhotoSmall.tsx

@@ -1,3 +1,5 @@
+'use client';
+
 import { Photo, altTextForPhoto } from '.';
 import ImageSmall from '@/components/ImageSmall';
 import Link from 'next/link';
@@ -6,6 +8,7 @@ import { pathForPhoto } from '@/site/paths';
 import { Camera } from '@/camera';
 import { FilmSimulation } from '@/simulation';
 import { SHOULD_PREFETCH_ALL_LINKS } from '@/site/config';
+import { useEffect, useRef } from 'react';
 
 export default function PhotoSmall({
   photo,
@@ -15,6 +18,7 @@ export default function PhotoSmall({
   selected,
   priority,
   prefetch = SHOULD_PREFETCH_ALL_LINKS,
+  onVisible,
 }: {
   photo: Photo
   tag?: string
@@ -23,9 +27,28 @@ export default function PhotoSmall({
   selected?: boolean
   priority?: boolean
   prefetch?: boolean
+  onVisible?: () => void
 }) {
+  const ref = useRef<HTMLAnchorElement>(null);
+
+  useEffect(() => {
+    if (onVisible && ref.current) {
+      const observer = new IntersectionObserver(e => {
+        if (e[0].isIntersecting) {
+          onVisible();
+        }
+      }, {
+        root: null,
+        threshold: 0,
+      });
+      observer.observe(ref.current);
+      return () => observer.disconnect();
+    }
+  }, [onVisible]);
+
   return (
     <Link
+      ref={ref}
       href={pathForPhoto(photo, tag, camera, simulation)}
       className={clsx(
         'flex w-full h-full',

src/photo/PhotosLarge.tsx

@@ -8,11 +8,13 @@ export default function PhotosLarge({
   animate = true,
   prefetchFirstPhotoLinks,
   revalidatePhoto,
+  onLastPhotoVisible,
 }: {
   photos: Photo[]
   animate?: boolean
   prefetchFirstPhotoLinks?: boolean
   revalidatePhoto?: RevalidatePhoto
+  onLastPhotoVisible?: () => void
 }) {
   return (
     <AnimateItems
@@ -29,6 +31,9 @@ export default function PhotosLarge({
           priority={index <= 1}
           prefetchRelatedLinks={prefetchFirstPhotoLinks && index === 0}
           revalidatePhoto={revalidatePhoto}
+          onVisible={index === photos.length - 1
+            ? onLastPhotoVisible
+            : undefined}
         />)}
       itemKeys={photos.map(photo => photo.id)}
     />