Gallery

A horizontal, view-aligned pager with generous margins so the neighbours peek in. The centered page sits at full size with a deep shadow; pages either side scale down, blur and darken by how far off-center they are, and shift slightly against the scroll for a parallax feel, all from scrollTransition. The ends rubber-band with scrollBounceBehavior(.always). A dot strip below tracks progress continuously as the scroll moves and can be scrubbed to jump pages. Pinch the centered page to peek-zoom with a soft limit; it springs back on release.

Notes

• Selection is a scrollPosition(id:) binding, so the centered page is always addressable and the strip can move it programmatically.
• The continuous progress for the dot indicator comes from onScrollGeometryChange on iOS 18; on iOS 17 the indicator still snaps to the selected page, it just does not track mid-scroll.
• The recede is a file-private VisualEffect function called from the scrollTransition closure, which keeps the closure nonisolated and cheap.
• The strip is an adjustable VoiceOver element (swipe to change page, value "n of m"); the pager is a container labeled "Gallery". Page changes tick with .selection.
• Reduce Motion drops the blur and the parallax shift and uses ease-outs; the scale and tone still change so the centered page remains distinct.
• pageWidth (fraction of the gallery width, default 0.78) and spacing (default 16) size the pages; the album uses 0.82 and 14 so the pages fill the screen with the neighbours just peeking.
• The album sets captions on solid block tabs inside each page and keeps actions in a floating capsule pinned with safeAreaInset, so the pager can scroll under it at large text sizes.
• DepthGalleryExample at the end of DepthGallery.swift is the Gallery screen from the preview; copy it as a starting point.