[Bug]: iOS 26.1 - Pinch gesture randomly jumping in Resumable Zoom

[astanb]

Summary

Firstly, thanks for the really useful library!

I'm seeing an issue only on iOS 26.1 (also on iOS 26.0.1, I hoped the update might fix it) where if I zoom using a pinch gesture sometimes the container seems to jump to an incorrect position. This behaviour isn't seen on an iOS 18.0.1 device. It seems to happen when the pinch gesture is of a certain duration, you can see towards the end of the ios 26 video that slower gestures don't exhibit the behaviour. The issue is most apparent around 5 seconds into the iOS 26 video. I'm not sure if it's an underlying gesture handler issue or not though.

ios18.mp4

ios26.mp4

Environment

"expo": "^54.0.0",
"react-native": "0.81.5",
"react-native-gesture-handler": "~2.28.0",
"react-native-reanimated": "^4.1.5",
"react-native-safe-area-context": "~5.6.0",
"react-native-worklets": "^0.6.1",
"react-native-zoom-toolkit": "^5.0.1"

iPhone 15 Pro running iOS 26.1
iPhone XR running iOS 18.0.1

Steps to Reproduce

Using identical code from https://glazzes.github.io/react-native-zoom-toolkit/guides/skia.html just using a larger image file from here https://images.pexels.com/photos/1379636/pexels-photo-1379636.jpeg

You'll need to use a device to reproduce it, it's very hard to do on the simulator. Perform a pinch zoom gesture off centre for about 200-500ms to trigger it.

[astanb]

Here's another video which shows the issue more clearly. I am pinching to zoom towards the right side of the screen.

ios26v2.mp4

[astanb]

Also seeing the issue in the Gallery component. I've narrowed it down to this line:

react-native-zoom-toolkit/src/commons/hooks/usePinchCommons.ts

Line 173 in 4aae7d8

scaleOffset.value = scale.value;

Commenting it out fixes the issue, but I'm not sure what repercussions it will have, I haven't noticed any unwanted behaviour so far with limited testing.

[Glazzes]

Hi @astanb, excuse the late response please. Based on what you say and has worked for you, I want to believe scaleOffset.value is capturing a previous value from scale.value rather than the latest one after the reset animation has finished, btw hasn't this line caused any trouble you as well?

Are you able to resume pinch gestures with out any trouble after commenting out that one line?

[astanb]

Thanks for the reply 👍

I’m not seeing issues since removing it, I did not have to remove/change the double tap gesture scale line you linked either.

[Glazzes]

I already pushed a commit with the change you mentioned, I gotta trust in your good will since I don't have an iPhone, you can refer to this comment about installing a library branch from Github.

Let me know how it works for you, this new version is for Expo 54 only btw.