Extract scroll preservation data collection
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@@ -73,14 +73,18 @@ const usePreserveOnWindowResize = (
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}, [readingMode, pageScaleMode, pageIndex]);
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};
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const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement | null>, readingMode: ReadingMode) => {
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const scrollPosition = useRef<{
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left: number;
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top: number;
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visibleElement: HTMLElement | undefined;
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visibleElementLeft: number;
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visibleElementTop: number;
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}>({
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interface ScrollPreservationInfo {
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left: number;
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top: number;
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visibleElement: HTMLElement | undefined;
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visibleElementLeft: number;
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visibleElementTop: number;
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}
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const useScrollPreservationData = (
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scrollElementRef: RefObject<HTMLElement | null>,
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): RefObject<ScrollPreservationInfo> => {
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const dataRef = useRef<ScrollPreservationInfo>({
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left: 0,
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top: 0,
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visibleElement: undefined,
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@@ -88,9 +92,6 @@ const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement
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visibleElementTop: 0,
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});
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const isContinuousReadingModeActive = isContinuousReadingMode(readingMode);
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const isContinuousVerticalReadingModeActive = isContinuousVerticalReadingMode(readingMode);
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useEffect(() => {
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const scrollElement = scrollElementRef.current;
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@@ -99,9 +100,9 @@ const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement
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}
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const onScroll = () => {
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const { visibleElement } = scrollPosition.current;
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scrollPosition.current = {
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...scrollPosition.current,
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const { visibleElement } = dataRef.current;
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dataRef.current = {
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...dataRef.current,
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left: scrollElement.scrollLeft,
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top: scrollElement.scrollTop,
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visibleElementLeft: visibleElement?.offsetLeft ?? 0,
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@@ -114,6 +115,59 @@ const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement
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return () => scrollElement.removeEventListener('scroll', onScroll);
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}, []);
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useEffect(() => {
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const scrollElement = scrollElementRef.current;
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if (!scrollElement) {
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return () => {};
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}
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const updateObservation = (nodes: NodeList, intersectionAction: (element: Element) => void) =>
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Array.from(nodes)
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.filter((node) => node instanceof HTMLElement)
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.flatMap((element) =>
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element instanceof HTMLImageElement ? [element] : Array.from(element.querySelectorAll('img')),
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)
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.forEach(intersectionAction);
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const intersectionObserver = new IntersectionObserver((entries) => {
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const firstVisibleElement = entries.find((entry) => entry.isIntersecting);
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if (!(firstVisibleElement?.target instanceof HTMLElement)) {
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return;
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}
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dataRef.current = {
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...dataRef.current,
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visibleElement: firstVisibleElement.target,
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visibleElementLeft: firstVisibleElement.target.offsetLeft,
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visibleElementTop: firstVisibleElement.target.offsetTop,
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};
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});
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const mutationObserver = new MutationObserver((entries) => {
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for (const entry of entries) {
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updateObservation(entry.addedNodes, (element) => intersectionObserver.observe(element));
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updateObservation(entry.removedNodes, (element) => intersectionObserver.unobserve(element));
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}
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});
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mutationObserver.observe(scrollElement, {
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childList: true,
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subtree: true,
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});
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return () => {
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mutationObserver.disconnect();
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intersectionObserver.disconnect();
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};
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}, []);
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return dataRef;
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};
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const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement | null>, readingMode: ReadingMode) => {
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const preservationData = useScrollPreservationData(scrollElementRef);
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const isContinuousReadingModeActive = isContinuousReadingMode(readingMode);
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const isContinuousVerticalReadingModeActive = isContinuousVerticalReadingMode(readingMode);
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useEffect(() => {
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const scrollElement = scrollElementRef.current;
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@@ -122,7 +176,7 @@ const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement
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}
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const preserveScrollPosition: ResizeObserverCallback = (entries) => {
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const { left, top, visibleElement, visibleElementLeft, visibleElementTop } = scrollPosition.current;
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const { left, top, visibleElement, visibleElementLeft, visibleElementTop } = preservationData.current;
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if (!visibleElement) {
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return;
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@@ -156,48 +210,19 @@ const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement
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scrollElement.scrollTo(newLeft, newTop);
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};
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const updateObservation = (
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nodes: NodeList,
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resizeAction: (element: Element) => void,
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intersectionAction: (element: Element) => void,
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) =>
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const updateObservation = (nodes: NodeList, resizeAction: (element: Element) => void) =>
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Array.from(nodes)
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.filter((node) => node instanceof HTMLElement)
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.flatMap((element) =>
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element instanceof HTMLImageElement ? [element] : Array.from(element.querySelectorAll('img')),
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)
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.forEach((element) => {
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resizeAction(element);
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intersectionAction(element);
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});
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.forEach(resizeAction);
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const resizeObserver = new ResizeObserver(preserveScrollPosition);
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const intersectionObserver = new IntersectionObserver((entries) => {
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const firstVisibleElement = entries.find((entry) => entry.isIntersecting);
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if (!(firstVisibleElement?.target instanceof HTMLElement)) {
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return;
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}
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scrollPosition.current = {
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...scrollPosition.current,
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visibleElement: firstVisibleElement.target,
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visibleElementLeft: firstVisibleElement.target.offsetLeft,
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visibleElementTop: firstVisibleElement.target.offsetTop,
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};
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});
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const mutationObserver = new MutationObserver((entries) => {
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for (const entry of entries) {
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updateObservation(
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entry.addedNodes,
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(element) => resizeObserver.observe(element),
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(element) => intersectionObserver.observe(element),
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);
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updateObservation(
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entry.removedNodes,
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(element) => resizeObserver.unobserve(element),
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(element) => intersectionObserver.unobserve(element),
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);
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updateObservation(entry.addedNodes, (element) => resizeObserver.observe(element));
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updateObservation(entry.removedNodes, (element) => resizeObserver.unobserve(element));
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}
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});
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@@ -209,7 +234,6 @@ const usePreserveOnLeadingPageRender = (scrollElementRef: RefObject<HTMLElement
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return () => {
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mutationObserver.disconnect();
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resizeObserver.disconnect();
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intersectionObserver.disconnect();
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};
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}, [isContinuousReadingModeActive, isContinuousVerticalReadingModeActive]);
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};
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