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joplin/packages/pdf-viewer/hooks/useScaledSize.ts

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import { useRef, useState, MutableRefObject } from 'react';
import useAsyncEffect, { AsyncEffectEvent } from '@joplin/lib/hooks/useAsyncEffect';
import PdfDocument from '../PdfDocument';
import { ScaledSize } from '../types';
export interface ScaledSizeParams {
pdfDocument: PdfDocument;
pdfId: string;
containerWidth: number;
rememberScroll: boolean;
anchorPage: number;
container: MutableRefObject<HTMLElement>;
innerContainerEl: MutableRefObject<HTMLElement>;
pageGap: number;
zoom: number;
}
const useScaledSize = ({ pdfDocument, pdfId, containerWidth, rememberScroll, anchorPage, container, innerContainerEl, pageGap, zoom }: ScaledSizeParams) => {
const [scaledSize, setScaledSize] = useState<ScaledSize>(null);
const currentScaleSize = useRef(scaledSize);
useAsyncEffect(async (event: AsyncEffectEvent) => {
if (!pdfDocument || !containerWidth) return;
// console.log('scaledSize calculation triggered');
const effectiveWidth = Math.min(containerWidth - 20, 900) * (zoom || 1);
const scaledSize_ = await pdfDocument.getScaledSize(null, effectiveWidth);
if (event.cancelled) return;
const oldScaleSize = currentScaleSize.current;
const oldScrollTop = container.current.scrollTop;
innerContainerEl.current.style.height = `${(scaledSize_.height + pageGap) * pdfDocument.pageCount}px`;
// Adjust scroll position after window resize to keep the same page visible
if (oldScaleSize && container.current) {
container.current.scrollTop = oldScrollTop * (scaledSize_.scale / oldScaleSize.scale);
}
currentScaleSize.current = scaledSize_;
setScaledSize(scaledSize_);
// If loading after note rerender, try to retirive the old scroll position
if (rememberScroll && pdfId && !oldScaleSize && !anchorPage) {
const scrollOffset = parseInt(sessionStorage.getItem(`pdf.${pdfId}.scrollTop`), 10) || null;
if (scrollOffset) {
// Adjusting it according to the new scale
container.current.scrollTop = scrollOffset * scaledSize_.scale;
// console.log('scroll set',container.current.scrollTop);
}
}
}, [pdfDocument, pdfId, rememberScroll, anchorPage, containerWidth, zoom]);
return scaledSize;
};
export default useScaledSize;