Implement other input event types in GPUI

[arguiot]

Description

GPUI currently supports a subset of available platform events. The macOS implementation shows that while cocoa-rs provides many more event types, GPUI only handles a limited set. This limitation prevents developers from implementing features that rely on platform-specific gestures and inputs, such as pinch-to-zoom for infinite canvas applications.

Current State

The current PlatformInput::from_native implementation on macOS handles:

• Mouse events (down, up, move, drag, exit)
• Keyboard events (down, up, flags changed)
• Scroll wheel events
• Limited swipe events (only for navigation)

However, cocoa-rs exposes many more event types that are currently ignored:

• NSMouseEntered (8)
• NSCursorUpdate (17)
• NSTabletPoint (23)
• NSTabletProximity (24)
• NSEventTypeGesture (29)
• NSEventTypeMagnify (30)
• NSEventTypeRotate (18)
• NSEventTypeBeginGesture (19)
• NSEventTypeEndGesture (20)
• NSEventTypePressure (34)

Use Cases

1. Infinite Canvas Applications: Pinch-to-zoom (magnify) and rotate gestures are essential for canvas manipulation
2. Drawing Applications: Tablet pressure events for pressure-sensitive drawing
3. Advanced UI Interactions: Mouse enter events for hover states, cursor updates for custom cursors
4. Creative Tools: Rotate gestures for object manipulation

Implementation Priority

High priority events (most commonly needed):

1. NSEventTypeMagnify - Essential for zoom functionality
2. NSMouseEntered - Common UI pattern
3. NSEventTypeRotate - Useful for canvas/object manipulation

Medium priority:

• NSEventTypeBeginGesture/NSEventTypeEndGesture - For gesture state management
• NSCursorUpdate - For custom cursor support

Lower priority:

• NSTabletPoint/NSTabletProximity/NSEventTypePressure - Specialized for drawing tablets

Platform Considerations

• macOS: Full support available through cocoa-rs
• Windows: Need to map to equivalent WM_GESTURE messages
• Linux: Support varies by compositor; may need feature detection