From 92789b2d38b11118a6c874367aaf140ca6db1051 Mon Sep 17 00:00:00 2001
From: Tom Butcher <thomasbutcher15@gmail.com>
Date: Sun, 13 Sep 2026 18:30:00 +0100
Subject: [PATCH] Implement Pinch Zoom and Scroll Preservation for PDF and
 Template Previews

- Added usePinchZoom and usePreserveZoomScroll hooks to enable pinch zoom functionality and maintain scroll position during zooming in PDFViewer and TemplatePreview components.
- Introduced a new clampPreviewScale function to ensure zoom levels remain within defined limits.
- Enhanced TemplatePreview with a zoom slider and overlay for better user interaction.
- Updated PDFViewer to handle scale changes and improve rendering performance.
- Refactored related components to support the new zooming features, enhancing overall user experience.
---
 assets/stylesheets/App.css                    |  22 ++
 .../Dashboard/common/PDFPreview.jsx           |   6 +-
 src/components/Dashboard/common/PDFViewer.jsx | 119 +++++++++--
 .../Dashboard/common/TemplatePreview.jsx      | 103 ++++++++--
 .../Dashboard/hooks/usePinchZoom.js           | 193 ++++++++++++++++++
 .../Dashboard/hooks/usePreserveZoomScroll.js  | 163 +++++++++++++++
 6 files changed, 570 insertions(+), 36 deletions(-)
 create mode 100644 src/components/Dashboard/hooks/usePinchZoom.js
 create mode 100644 src/components/Dashboard/hooks/usePreserveZoomScroll.js

diff --git a/assets/stylesheets/App.css b/assets/stylesheets/App.css
index 2290b9ae..d0e7d61d 100644
--- a/assets/stylesheets/App.css
+++ b/assets/stylesheets/App.css
@@ -2470,6 +2470,28 @@ body.objectKanbanColumnResizing * {
   pointer-events: none;
 }
 
+.previewZoomOverlay {
+  position: absolute;
+  right: 12px;
+  bottom: 12px;
+  z-index: 2;
+}
+
+.previewZoomCard {
+  background-color: color-mix(
+    in srgb,
+    var(--layout-header-bg) 80%,
+    transparent
+  );
+  backdrop-filter: blur(8px);
+  -webkit-backdrop-filter: blur(8px);
+}
+
+.ant-slider .ant-slider-handle.previewZoomSliderHandle::after {
+  box-shadow: 0 0 0 2px var(--color-primary);
+  background: var(--color-primary);
+}
+
 .react-pdf__Page {
   border: 1px solid #000;
   box-shadow: 0 0 5px rgba(0, 0, 0, 0.2);
diff --git a/src/components/Dashboard/common/PDFPreview.jsx b/src/components/Dashboard/common/PDFPreview.jsx
index 78fceab0..a1b7ceb9 100644
--- a/src/components/Dashboard/common/PDFPreview.jsx
+++ b/src/components/Dashboard/common/PDFPreview.jsx
@@ -6,6 +6,7 @@ import MinusIcon from '../../Icons/MinusIcon.jsx'
 import PanIcon from '../../Icons/PanIcon.jsx'
 import PanFilledIcon from '../../Icons/PanFilledIcon.jsx'
 import PDFViewer from './PDFViewer.jsx'
+import { clampPreviewScale } from '../hooks/usePinchZoom.js'
 
 const PDFPreview = ({ file, loading = false, style }) => {
   const [previewScale, setPreviewScale] = useState(1)
@@ -30,14 +31,14 @@ const PDFPreview = ({ file, loading = false, style }) => {
         <Button
           icon={<PlusIcon />}
           onClick={() => {
-            setPreviewScale((prev) => prev + 0.05)
+            setPreviewScale((prev) => clampPreviewScale(prev + 0.05))
           }}
           disabled={loading}
         />
         <Button
           icon={<MinusIcon />}
           onClick={() => {
-            setPreviewScale((prev) => Math.max(0.1, prev - 0.05))
+            setPreviewScale((prev) => clampPreviewScale(prev - 0.05))
           }}
           disabled={loading}
         />
@@ -63,6 +64,7 @@ const PDFPreview = ({ file, loading = false, style }) => {
         <PDFViewer
           file={file}
           scale={previewScale}
+          onScaleChange={setPreviewScale}
           panMode={panMode}
           loading={loading}
         />
diff --git a/src/components/Dashboard/common/PDFViewer.jsx b/src/components/Dashboard/common/PDFViewer.jsx
index f496d416..74dba829 100644
--- a/src/components/Dashboard/common/PDFViewer.jsx
+++ b/src/components/Dashboard/common/PDFViewer.jsx
@@ -1,4 +1,10 @@
-import { useCallback, useEffect, useRef, useState } from 'react'
+import {
+  useCallback,
+  useEffect,
+  useLayoutEffect,
+  useRef,
+  useState
+} from 'react'
 import PropTypes from 'prop-types'
 import { Document, Page, pdfjs } from 'react-pdf'
 import pdfWorker from 'pdfjs-dist/build/pdf.worker.min.mjs?url'
@@ -6,6 +12,8 @@ import 'react-pdf/dist/Page/AnnotationLayer.css'
 import 'react-pdf/dist/Page/TextLayer.css'
 import LoadingPlaceholder from './LoadingPlaceholder.jsx'
 import ScrollBox from './ScrollBox.jsx'
+import usePreserveZoomScroll from '../hooks/usePreserveZoomScroll.js'
+import usePinchZoom from '../hooks/usePinchZoom.js'
 
 pdfjs.GlobalWorkerOptions.workerSrc = pdfWorker
 
@@ -16,10 +24,14 @@ const PDFViewer = ({
   scale = 1,
   panMode = false,
   loading = false,
+  onScaleChange,
   onLoadSuccess = noop,
   onLoadError = noop
 }) => {
+  const containerRef = useRef(null)
   const scrollElementRef = useRef(null)
+  const zoomContentRef = useRef(null)
+  const pdfPagesRef = useRef(null)
   const panStartRef = useRef({ x: 0, y: 0, scrollLeft: 0, scrollTop: 0 })
   const pdfDocumentRef = useRef(null)
   const prevFileRef = useRef(file)
@@ -27,6 +39,8 @@ const PDFViewer = ({
   const [numPages, setNumPages] = useState(0)
   const [isPanning, setIsPanning] = useState(false)
   const [hasLoadError, setHasLoadError] = useState(false)
+  const [pdfSize, setPdfSize] = useState({ width: 0, height: 0 })
+  const [renderedScale, setRenderedScale] = useState(scale)
 
   const activeFile = loading == true ? null : file
   if (prevFileRef.current !== activeFile) {
@@ -65,11 +79,48 @@ const PDFViewer = ({
   useEffect(() => {
     setNumPages(0)
     setHasLoadError(false)
+    setPdfSize({ width: 0, height: 0 })
     return () => {
       destroyPdfDocument()
     }
   }, [activeFile, destroyPdfDocument])
 
+  useEffect(() => {
+    if (scale === renderedScale) {
+      return undefined
+    }
+
+    const timeout = window.setTimeout(() => {
+      setRenderedScale(scale)
+    }, 500)
+    return () => window.clearTimeout(timeout)
+  }, [renderedScale, scale])
+
+  useLayoutEffect(() => {
+    const pages = pdfPagesRef.current
+    if (!pages || typeof ResizeObserver !== 'function') {
+      return undefined
+    }
+
+    const updatePdfSize = () => {
+      const width = pages.offsetWidth / renderedScale
+      const height = pages.offsetHeight / renderedScale
+      if (width <= 0 && height <= 0) {
+        return
+      }
+      setPdfSize((prev) =>
+        prev.width === width && prev.height === height
+          ? prev
+          : { width, height }
+      )
+    }
+
+    updatePdfSize()
+    const observer = new ResizeObserver(updatePdfSize)
+    observer.observe(pages)
+    return () => observer.disconnect()
+  }, [activeFile, numPages, renderedScale])
+
   useEffect(() => {
     if (!panMode) {
       setIsPanning(false)
@@ -138,12 +189,31 @@ const PDFViewer = ({
     }
   }, [isPanning])
 
+  const { captureAtClientPoint } = usePreserveZoomScroll(
+    scrollElementRef,
+    zoomContentRef,
+    scale,
+    `${documentKeyRef.current}:${numPages}`
+  )
+
+  usePinchZoom({
+    containerRef,
+    scale,
+    onScaleChange,
+    onBeforeScaleChange: captureAtClientPoint,
+    enabled: typeof onScaleChange === 'function' && loading != true
+  })
+
   const isDocumentLoading =
     Boolean(activeFile) && numPages === 0 && hasLoadError != true
   const showLoadingPlaceholder = loading == true || isDocumentLoading
+  const scaledPdfWidth = pdfSize.width * scale
+  const scaledPdfHeight = pdfSize.height * scale
+  const liveTransformScale = scale / renderedScale
 
   return (
     <div
+      ref={containerRef}
       style={{
         height: '100%',
         minHeight: 0,
@@ -194,25 +264,39 @@ const PDFViewer = ({
               onLoadError={handleDocumentLoadError}
             >
               <div
+                ref={zoomContentRef}
                 style={{
-                  display: 'flex',
-                  flexDirection: 'row',
-                  alignItems: 'flex-start',
-                  justifyContent: 'center',
-                  gap: 32,
-                  width: 'max-content',
-                  minWidth: '100%'
+                  width: scaledPdfWidth || undefined,
+                  height: scaledPdfHeight || undefined,
+                  margin: '0 auto'
                 }}
               >
-                {Array.from(new Array(numPages), (_el, index) => (
-                  <Page
-                    key={`page_${index + 1}`}
-                    pageNumber={index + 1}
-                    scale={scale}
-                    renderTextLayer={panMode != true}
-                    renderAnnotationLayer={panMode != true}
-                  />
-                ))}
+                <div
+                  ref={pdfPagesRef}
+                  style={{
+                    display: 'flex',
+                    flexDirection: 'row',
+                    alignItems: 'flex-start',
+                    justifyContent: 'center',
+                    gap: 32 * renderedScale,
+                    width: 'max-content',
+                    transform:
+                      liveTransformScale === 1
+                        ? undefined
+                        : `scale(${liveTransformScale})`,
+                    transformOrigin: 'top left'
+                  }}
+                >
+                  {Array.from(new Array(numPages), (_el, index) => (
+                    <Page
+                      key={`page_${index + 1}`}
+                      pageNumber={index + 1}
+                      scale={renderedScale}
+                      renderTextLayer={panMode != true}
+                      renderAnnotationLayer={panMode != true}
+                    />
+                  ))}
+                </div>
               </div>
             </Document>
           </div>
@@ -232,6 +316,7 @@ PDFViewer.propTypes = {
   scale: PropTypes.number,
   panMode: PropTypes.bool,
   loading: PropTypes.bool,
+  onScaleChange: PropTypes.func,
   onLoadSuccess: PropTypes.func,
   onLoadError: PropTypes.func
 }
diff --git a/src/components/Dashboard/common/TemplatePreview.jsx b/src/components/Dashboard/common/TemplatePreview.jsx
index 251e530b..b8e65f30 100644
--- a/src/components/Dashboard/common/TemplatePreview.jsx
+++ b/src/components/Dashboard/common/TemplatePreview.jsx
@@ -19,6 +19,14 @@ import ScrollBox from './ScrollBox.jsx'
 import { ApiServerContext } from '../context/ApiServerContext.jsx'
 import ProgressDisplay from './ProgressDisplay.jsx'
 import { CaretDownFilled } from '@ant-design/icons'
+import { Slider } from 'antd'
+import usePreserveZoomScroll from '../hooks/usePreserveZoomScroll.js'
+import usePinchZoom, {
+  clampPreviewScale,
+  MAX_PREVIEW_SCALE,
+  MIN_PREVIEW_SCALE
+} from '../hooks/usePinchZoom.js'
+import KeyboardShortcut from './KeyboardShortcut.jsx'
 const noop = () => {}
 
 const scaleCssSize = (size, scale) => {
@@ -52,6 +60,7 @@ const TemplatePreview = ({
   const defaultPreviewWidth = capabilities.defaultWidth || 600
   const iframeRef = useRef(null)
   const scrollElementRef = useRef(null)
+  const zoomContentRef = useRef(null)
   const savedScrollRef = useRef({ top: 0, left: 0 })
   const iframeSizeObserverRef = useRef(null)
   const previewRequestIdRef = useRef(0)
@@ -79,6 +88,7 @@ const TemplatePreview = ({
   })
 
   const toolbarRef = useRef(null)
+  const previewPaneRef = useRef(null)
   const [usePopoverSettings, setUsePopoverSettings] = useState(false)
 
   useLayoutEffect(() => {
@@ -106,7 +116,11 @@ const TemplatePreview = ({
       return
     }
 
-    if (showWidthControl && !doc.querySelector('.previewDocument') && doc.body) {
+    if (
+      showWidthControl &&
+      !doc.querySelector('.previewDocument') &&
+      doc.body
+    ) {
       const container = doc.createElement('div')
       container.className = 'previewContainer'
       const pages = doc.createElement('div')
@@ -234,6 +248,25 @@ const TemplatePreview = ({
     restoreScrollPosition()
   }, [iframeSize, restoreScrollPosition])
 
+  const { captureAtClientPoint } = usePreserveZoomScroll(
+    scrollElementRef,
+    zoomContentRef,
+    previewScale,
+    previewType == 'HTML'
+      ? `${iframeSize.width}x${iframeSize.height}`
+      : 'pdf-inactive'
+  )
+
+  usePinchZoom({
+    containerRef: previewPaneRef,
+    iframeRef,
+    iframeBindKey: previewContentHTML,
+    scale: previewScale,
+    onScaleChange: setPreviewScale,
+    onBeforeScaleChange: captureAtClientPoint,
+    enabled: previewType == 'HTML' && !loading && !reloadLoading
+  })
+
   useLayoutEffect(() => {
     if (previewType != 'HTML') {
       return
@@ -585,23 +618,31 @@ const TemplatePreview = ({
 
   const toolbarContent = (
     <>
-      <Button
-        icon={
-          panMode ? (
-            <PanFilledIcon style={{ color: 'var(--color-primary)' }} />
-          ) : (
-            <PanIcon />
-          )
-        }
-        disabled={loading || reloadLoading}
-        onClick={() => {
+      <KeyboardShortcut
+        shortcut={'alt+p'}
+        hint={'ALT P'}
+        onTrigger={() => {
           setPanMode((prev) => !prev)
         }}
-      />
+      >
+        <Button
+          icon={
+            panMode ? (
+              <PanFilledIcon style={{ color: 'var(--color-primary)' }} />
+            ) : (
+              <PanIcon />
+            )
+          }
+          disabled={loading || reloadLoading}
+          onClick={() => {
+            setPanMode((prev) => !prev)
+          }}
+        />
+      </KeyboardShortcut>
       <Button
         icon={<PlusIcon />}
         onClick={() => {
-          setPreviewScale((prev) => prev + 0.05)
+          setPreviewScale((prev) => clampPreviewScale(prev + 0.05))
         }}
         disabled={loading || reloadLoading}
       />
@@ -618,7 +659,7 @@ const TemplatePreview = ({
       <Button
         icon={<MinusIcon />}
         onClick={() => {
-          setPreviewScale((prev) => Math.max(0.1, prev - 0.05))
+          setPreviewScale((prev) => clampPreviewScale(prev - 0.05))
         }}
         disabled={loading || reloadLoading}
       />
@@ -641,7 +682,7 @@ const TemplatePreview = ({
             { value: 'HTML', label: 'HTML' },
             { value: 'PDF', label: 'PDF' }
           ]}
-          style
+          style={{ minWidth: 79 }}
           loading={(loading || reloadLoading) && !usePopoverSettings}
           disabled={loading || reloadLoading}
           value={previewType}
@@ -704,6 +745,7 @@ const TemplatePreview = ({
       </Flex>
 
       <div
+        ref={previewPaneRef}
         style={{
           flex: '1 1 auto',
           minHeight: 0,
@@ -741,7 +783,31 @@ const TemplatePreview = ({
             </Flex>
           ) : null}
         </div>
-
+        <div className='previewZoomOverlay'>
+          <Card
+            style={{ borderRadius: 18 }}
+            styles={{ body: { padding: '10px 17px', width: 200 } }}
+            className='previewZoomCard'
+          >
+            <Slider
+              min={MIN_PREVIEW_SCALE}
+              max={MAX_PREVIEW_SCALE}
+              step={0.05}
+              tooltip={{ open: false }}
+              value={previewScale}
+              style={{ margin: 0 }}
+              onChange={(value) => setPreviewScale(value)}
+              classNames={{
+                handle: 'previewZoomSliderHandle'
+              }}
+              styles={{
+                track: {
+                  background: 'var(--color-primary)'
+                }
+              }}
+            />
+          </Card>
+        </div>
         {previewType == 'HTML' ? (
           <ScrollBox
             scrollableNodeProps={{ ref: scrollElementRef }}
@@ -760,6 +826,7 @@ const TemplatePreview = ({
               }}
             >
               <div
+                ref={zoomContentRef}
                 style={{
                   width: scaledIframeWidth,
                   height: scaledIframeHeight,
@@ -779,7 +846,8 @@ const TemplatePreview = ({
                   style={{
                     width:
                       iframeSize.width === '100%' ? '100%' : iframeSize.width,
-                    height: iframeSize.height === 'auto' ? 150 : iframeSize.height,
+                    height:
+                      iframeSize.height === 'auto' ? 150 : iframeSize.height,
                     display: 'block',
                     border: 0,
                     overflow: 'hidden',
@@ -795,6 +863,7 @@ const TemplatePreview = ({
           <PDFViewer
             file={pdfBlob}
             scale={previewScale}
+            onScaleChange={setPreviewScale}
             panMode={panMode}
             loading={false}
             onLoadError={() => {
diff --git a/src/components/Dashboard/hooks/usePinchZoom.js b/src/components/Dashboard/hooks/usePinchZoom.js
new file mode 100644
index 00000000..ad2f06a5
--- /dev/null
+++ b/src/components/Dashboard/hooks/usePinchZoom.js
@@ -0,0 +1,193 @@
+import { useCallback, useEffect, useRef } from 'react'
+
+export const MIN_PREVIEW_SCALE = 0.1
+export const MAX_PREVIEW_SCALE = 5
+
+const isPinchZoomEvent = (event) => event.ctrlKey || event.metaKey
+
+export const clampPreviewScale = (value) => {
+  if (!Number.isFinite(value)) {
+    return 1
+  }
+  const clamped = Math.min(MAX_PREVIEW_SCALE, Math.max(MIN_PREVIEW_SCALE, value))
+  return Math.round(clamped * 10000) / 10000
+}
+
+const nextScaleFromWheel = (scale, event) => {
+  const intensity = event.deltaMode === 1 ? 0.12 : 0.0045
+  return clampPreviewScale(scale * Math.exp(-event.deltaY * intensity))
+}
+
+const eventClientPoint = (event, iframeRef, scale) => {
+  const iframe = iframeRef?.current
+  const eventDoc = event.target?.ownerDocument
+  if (
+    iframe &&
+    eventDoc &&
+    eventDoc !== document &&
+    eventDoc === iframe.contentDocument
+  ) {
+    const rect = iframe.getBoundingClientRect()
+    return {
+      clientX: rect.left + event.clientX * scale,
+      clientY: rect.top + event.clientY * scale
+    }
+  }
+  return { clientX: event.clientX, clientY: event.clientY }
+}
+
+const usePinchZoom = ({
+  containerRef,
+  iframeRef,
+  iframeBindKey,
+  scale = 1,
+  onScaleChange,
+  onBeforeScaleChange,
+  enabled = true
+}) => {
+  const onScaleChangeRef = useRef(onScaleChange)
+  onScaleChangeRef.current = onScaleChange
+  const onBeforeScaleChangeRef = useRef(onBeforeScaleChange)
+  onBeforeScaleChangeRef.current = onBeforeScaleChange
+  const scaleRef = useRef(scale)
+  scaleRef.current = scale
+  const gestureStartScaleRef = useRef(scale)
+  const enabledRef = useRef(enabled)
+  enabledRef.current = enabled
+
+  const handleWheel = useCallback(
+    (event) => {
+      if (!enabledRef.current || !isPinchZoomEvent(event)) {
+        return
+      }
+      if (event.target?.closest?.('.previewZoomOverlay')) {
+        return
+      }
+
+      event.preventDefault()
+      event.stopPropagation()
+
+      const current = scaleRef.current
+      const next = nextScaleFromWheel(current, event)
+      if (next === current) {
+        return
+      }
+
+      const point = eventClientPoint(event, iframeRef, current)
+      onBeforeScaleChangeRef.current?.(point.clientX, point.clientY)
+      onScaleChangeRef.current?.(next)
+    },
+    [iframeRef]
+  )
+
+  const handleGestureStart = useCallback((event) => {
+    if (!enabledRef.current) {
+      return
+    }
+    event.preventDefault()
+    gestureStartScaleRef.current = scaleRef.current
+  }, [])
+
+  const handleGestureChange = useCallback(
+    (event) => {
+      if (!enabledRef.current) {
+        return
+      }
+      event.preventDefault()
+      const startScale = gestureStartScaleRef.current
+      if (!Number.isFinite(startScale)) {
+        return
+      }
+      const next = clampPreviewScale(startScale * event.scale)
+      if (next === scaleRef.current) {
+        return
+      }
+      const point = eventClientPoint(event, iframeRef, scaleRef.current)
+      onBeforeScaleChangeRef.current?.(point.clientX, point.clientY)
+      onScaleChangeRef.current?.(next)
+    },
+    [iframeRef]
+  )
+
+  useEffect(() => {
+    const container = containerRef?.current
+    if (!container || !enabled || typeof onScaleChange !== 'function') {
+      return undefined
+    }
+
+    const options = { capture: true, passive: false }
+    container.addEventListener('wheel', handleWheel, options)
+    container.addEventListener('gesturestart', handleGestureStart, options)
+    container.addEventListener('gesturechange', handleGestureChange, options)
+    return () => {
+      container.removeEventListener('wheel', handleWheel, options)
+      container.removeEventListener('gesturestart', handleGestureStart, options)
+      container.removeEventListener(
+        'gesturechange',
+        handleGestureChange,
+        options
+      )
+    }
+  }, [
+    containerRef,
+    enabled,
+    handleGestureChange,
+    handleGestureStart,
+    handleWheel,
+    onScaleChange
+  ])
+
+  useEffect(() => {
+    const iframe = iframeRef?.current
+    if (!iframe || !enabled || typeof onScaleChange !== 'function') {
+      return undefined
+    }
+
+    const options = { capture: true, passive: false }
+    let boundDoc = null
+
+    const unbind = () => {
+      if (!boundDoc) {
+        return
+      }
+      boundDoc.removeEventListener('wheel', handleWheel, options)
+      boundDoc.removeEventListener('gesturestart', handleGestureStart, options)
+      boundDoc.removeEventListener(
+        'gesturechange',
+        handleGestureChange,
+        options
+      )
+      boundDoc = null
+    }
+
+    const bind = () => {
+      const doc = iframe.contentDocument
+      if (!doc || boundDoc === doc) {
+        return
+      }
+      unbind()
+      doc.addEventListener('wheel', handleWheel, options)
+      doc.addEventListener('gesturestart', handleGestureStart, options)
+      doc.addEventListener('gesturechange', handleGestureChange, options)
+      boundDoc = doc
+    }
+
+    iframe.addEventListener('load', bind)
+    bind()
+
+    return () => {
+      iframe.removeEventListener('load', bind)
+      unbind()
+    }
+  }, [
+    enabled,
+    handleGestureChange,
+    handleGestureStart,
+    handleWheel,
+    iframeBindKey,
+    iframeRef,
+    onScaleChange
+  ])
+}
+
+export default usePinchZoom
diff --git a/src/components/Dashboard/hooks/usePreserveZoomScroll.js b/src/components/Dashboard/hooks/usePreserveZoomScroll.js
new file mode 100644
index 00000000..25dd1c8d
--- /dev/null
+++ b/src/components/Dashboard/hooks/usePreserveZoomScroll.js
@@ -0,0 +1,163 @@
+import { useCallback, useEffect, useLayoutEffect, useRef } from 'react'
+
+const captureZoomScrollMetrics = (scrollEl, contentEl, scale) => {
+  if (!scrollEl || !contentEl) {
+    return null
+  }
+
+  const contentRect = contentEl.getBoundingClientRect()
+  if (contentRect.width <= 0 && contentRect.height <= 0) {
+    return null
+  }
+
+  const scrollRect = scrollEl.getBoundingClientRect()
+  return {
+    scale,
+    scrollLeft: scrollEl.scrollLeft,
+    scrollTop: scrollEl.scrollTop,
+    clientWidth: scrollEl.clientWidth,
+    clientHeight: scrollEl.clientHeight,
+    contentWidth: contentRect.width,
+    contentHeight: contentRect.height,
+    contentOffsetLeft: contentRect.left - scrollRect.left + scrollEl.scrollLeft,
+    contentOffsetTop: contentRect.top - scrollRect.top + scrollEl.scrollTop
+  }
+}
+
+const restoreZoomScrollOrigin = (scrollEl, contentEl, prev, nextScale) => {
+  if (!scrollEl || !contentEl || !prev?.scale || prev.scale === nextScale) {
+    return
+  }
+
+  const ratio = nextScale / prev.scale
+  if (!Number.isFinite(ratio) || ratio <= 0) {
+    return
+  }
+
+  const anchorX = Number.isFinite(prev.anchorX)
+    ? prev.anchorX
+    : prev.clientWidth / 2
+  const anchorY = Number.isFinite(prev.anchorY)
+    ? prev.anchorY
+    : prev.clientHeight / 2
+  const pointX = prev.scrollLeft + anchorX - prev.contentOffsetLeft
+  const pointY = prev.scrollTop + anchorY - prev.contentOffsetTop
+
+  const scrollRect = scrollEl.getBoundingClientRect()
+  const contentRect = contentEl.getBoundingClientRect()
+  const contentOffsetLeft =
+    contentRect.left - scrollRect.left + scrollEl.scrollLeft
+  const contentOffsetTop =
+    contentRect.top - scrollRect.top + scrollEl.scrollTop
+
+  scrollEl.scrollTo(
+    contentOffsetLeft + pointX * ratio - anchorX,
+    contentOffsetTop + pointY * ratio - anchorY
+  )
+}
+
+const usePreserveZoomScroll = (
+  scrollElementRef,
+  contentElementRef,
+  scale,
+  layoutKey
+) => {
+  const metricsRef = useRef(null)
+  const pendingRef = useRef(null)
+  const scaleRef = useRef(scale)
+  scaleRef.current = scale
+
+  const captureMetrics = useCallback(() => {
+    if (pendingRef.current) {
+      return
+    }
+
+    const metrics = captureZoomScrollMetrics(
+      scrollElementRef.current,
+      contentElementRef.current,
+      scaleRef.current
+    )
+    if (metrics) {
+      metricsRef.current = metrics
+    }
+  }, [contentElementRef, scrollElementRef])
+
+  const captureAtClientPoint = useCallback(
+    (clientX, clientY) => {
+      const scrollEl = scrollElementRef.current
+      const metrics = captureZoomScrollMetrics(
+        scrollEl,
+        contentElementRef.current,
+        scaleRef.current
+      )
+      if (!metrics || !scrollEl) {
+        return
+      }
+
+      const rect = scrollEl.getBoundingClientRect()
+      metrics.anchorX = clientX - rect.left
+      metrics.anchorY = clientY - rect.top
+      metricsRef.current = metrics
+    },
+    [contentElementRef, scrollElementRef]
+  )
+
+  const tryRestore = useCallback(() => {
+    const pending = pendingRef.current
+    const scrollEl = scrollElementRef.current
+    const contentEl = contentElementRef.current
+    if (!pending || !scrollEl || !contentEl) {
+      captureMetrics()
+      return
+    }
+
+    const contentRect = contentEl.getBoundingClientRect()
+    const sizeChanged =
+      Math.abs(contentRect.width - pending.prev.contentWidth) > 0.5 ||
+      Math.abs(contentRect.height - pending.prev.contentHeight) > 0.5
+    if (!sizeChanged) {
+      return
+    }
+
+    restoreZoomScrollOrigin(scrollEl, contentEl, pending.prev, pending.nextScale)
+    pendingRef.current = null
+    captureMetrics()
+  }, [captureMetrics, contentElementRef, scrollElementRef])
+
+  useLayoutEffect(() => {
+    const prev = metricsRef.current
+    if (prev && prev.scale !== scale) {
+      pendingRef.current = { prev, nextScale: scale }
+    }
+    tryRestore()
+  }, [layoutKey, scale, tryRestore])
+
+  useLayoutEffect(() => {
+    const contentEl = contentElementRef.current
+    if (!contentEl || typeof ResizeObserver !== 'function') {
+      return undefined
+    }
+
+    const observer = new ResizeObserver(() => {
+      tryRestore()
+    })
+    observer.observe(contentEl)
+    return () => observer.disconnect()
+  }, [contentElementRef, layoutKey, tryRestore])
+
+  useEffect(() => {
+    const scrollEl = scrollElementRef.current
+    if (!scrollEl) {
+      return undefined
+    }
+
+    scrollEl.addEventListener('scroll', captureMetrics, { passive: true })
+    return () => {
+      scrollEl.removeEventListener('scroll', captureMetrics)
+    }
+  }, [captureMetrics, layoutKey, scrollElementRef])
+
+  return { captureAtClientPoint }
+}
+
+export default usePreserveZoomScroll