fix(android): restore zoom and scroll offset when the view is re-attached to the window#1028
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…ched to the window The base PDFView calls recycle() in onDetachedFromWindow, resetting zoom, currentXOffset and currentYOffset. PdfView.onAttachedToWindow then reloads via drawPdf(), landing at the top of defaultPage — so any detach without unmount (a react-navigation screen stacked on top, a tab switch, a device rotation) loses the user's reading position and zoom. Snapshot the viewport before the base class recycles and restore it in loadComplete after the re-attach reload. The restore is post()-ed because the internal loadComplete fires the onLoad callback before jumpTo(defaultPage); a synchronous restore would be overwritten. The saved path guards against the source changing between detach and re-attach. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Problem
On Android, the base
PDFViewcallsrecycle()inonDetachedFromWindow, which resetszoom,currentXOffset, andcurrentYOffset.PdfView.onAttachedToWindowthen reloads the document viadrawPdf(), which lands at the top ofdefaultPage.So whenever the view is detached from the window without being unmounted — a react-navigation / react-native-screens screen pushed on top, a bottom-tab switch, a device rotation — the user loses their reading position and pinch zoom when they return to the PDF.
This is a long-standing pain point: #224, #275, #329, #380 all describe variants of it.
Fix
onDetachedFromWindow(new override): snapshotgetZoom(),getCurrentXOffset(),getCurrentYOffset()and the currentpathbefore callingsuper, where the base class recycles. Only taken when the view isn't already recycled.loadComplete: if a snapshot exists and thepathis unchanged, restore the viewport (zoomTo→moveTo→loadPages()).The restore is
post()-ed deliberately: the base class's internalloadCompleteinvokes theonLoadcallback beforejumpTo(defaultPage), so a synchronous restore would be immediately overwritten by that jump.The path guard means a source change between detach and re-attach behaves exactly as before (fresh load, no restore). No API change, no new props; iOS is unaffected.
Testing
Tested in a production cruise-line app (React Native 0.86, new architecture/Fabric, expo-router with react-native-screens native stack) on Android: with this change, scroll position and pinch zoom survive another screen being stacked over the PDF viewer and closed again — previously the document reloaded at the top of the last page with zoom reset. By the same mechanism this should also cover the tab-switch and rotation reports in the linked issues.