[Bug]: Gallery resets zoom to 1 on redundant rootSize writes (double-tap only)

[overlordSX]

Summary

Double-tap zoom on Gallery is cancelled almost immediately: scale moves off 1 for few frames, then reset forces it back to 1. Pinch zoom is not affected and stays at the pinched scale.

video_2026-09-07_19-04-55-optimized.mp4

What happens

GalleryGestureHandler resets transform on every rootSize write:

useAnimatedReaction(
  () => ({
    width: rootSize.width.value,
    height: rootSize.height.value,
  }),
  () => reset(0, 0, minScale, false),
  [rootSize]
);

measureRoot (onLayout) always does rootSize.width.set(width) / height.set(height), even when the size did not change. In Reanimated 3/4, assigning the same number still notifies listeners, so this reaction fires and cancels the in-flight double-tap animation.

Observed:

• Double-tap starts withTiming toward maxScale, then scale is forced to 1 (onZoomBegin at ~1.000…, immediately onZoomEnd at 1). Zoom never reaches maxScale.
• Pinch zoom works and keeps its scale. The reset only shows up on double-tap.
• Reset is still correct on a real size change (rotation / resize), but not on a repeated layout with the same width/height.

Secondary: tap / double-tap lose Gesture.Race

const composed = Gesture.Race(pan, pinch, composedTaps);

Pan activates on tiny movement, so single tap / double-tap often lose the race and onTap never fires. Pinch already uses manualActivation (2 touches only), so it does not need to race against taps.

Also, onDoubleTapStart / onDoubleTapEnd exist on GalleryProps but are not forwarded from Gallery.tsx into GalleryGestureHandler.

Suggested fix

1. In the reaction, compare current vs previous and skip reset when width/height are unchanged (and on the first run).
2. In measureRoot, return early if rootSize already has the same width/height.
3. Optional: Simultaneous(pinch, Race(pan, taps)) + pan.minDistance(10) so taps can win without delaying swipe. Exclusive(taps, pan) is a bad substitute — pan then waits for the double-tap timeout (~250ms) and swipes break.

Happy to open a PR if this direction is ok.

Environment

• Platform: Android
• react-native-zoom-toolkit: 5.1.1
• react-native: 0.87.0
• react: 19.2.3
• react-native-reanimated: 4.6.0
• react-native-gesture-handler: 3.2.1
• react-native-worklets: 0.12.1

Steps to Reproduce

1. Render Gallery with at least two images, zoomEnabled, default maxScale.
2. Double-tap an item.
3. Observe scale: one frame above 1, then back to 1. onZoomBegin fires, then immediately onZoomEnd. Zoom never reaches maxScale.
4. Pinch the same item to ~3×: scale stays. The bug is double-tap only.