feat: Initial clean release of CHM

packages/pdf-viewer/hooks/useScaledSize.ts

@@ -0,0 +1,56 @@
+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 = `${(scaledSize_.height + pageGap) * pdfDocument.pageCount}px`;
+
+		// Adjust scroll position after window resize to keep the same page visible
+		if (oldScaleSize && container.current) {
+			container.current.scrollTop = oldScrollTop * (scaledSize_.scale / oldScaleSize.scale);
+		}
+
+		currentScaleSize.current = scaledSize_;
+		setScaledSize(scaledSize_);
+
+		// If loading after note rerender, try to retrieve the old scroll position
+		if (rememberScroll && pdfId && !oldScaleSize && !anchorPage) {
+			const scrollOffset = parseInt(sessionStorage.getItem(`pdf.${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;