Phase 2: Navigation, Gestures, Animations, Input Preservation

[codelynx]

Phase 2 — Cross-Platform Features

These are core library features (Sources/SwiftOpenUI/) with backend rendering on all platforms. Design in core first, then implement per-backend.

1. Navigation

• NavigationStack view, NavigationLink view, NavigationPath
• Each backend manages a back stack (Compose navigation, GTK stack, Win32 pages, browser history, etc.)

2. Gestures

• .onTapGesture {}, .onLongPressGesture {}
• DragGesture with .onChanged / .onEnded
• Core modifier views + per-backend event wiring

3. Animations

• withAnimation { } block
• .animation(.easeInOut, value:) modifier
• Initial scope: opacity and offset transitions
• Compose has built-in animation APIs; other backends need platform-specific interpolation

4. Input-State Preservation

• Cursor position, selection range, IME composition, focus survival across rebuilds
• Currently all backends use full-rebuild model — cursor/focus is lost on state change
• Options: save/restore snapshots (like Win32's FocusSnapshot), or cross-platform diff engine
• Trigger: TextField UX on any platform

Platforms

Work happens across all 5 platforms: macOS, Linux (GTK4), Windows (Win32), Web (Wasm), Android (Compose).

Branch

Work on develop. Create experimental/phase2-* branches for individual features if needed.