The web canvas is a GPUI `native_surface` element, which on macOS
attaches an `NSView` (with a Metal-backed `CALayer`) as an AppKit
overlay on top of the GPUI render layer. GPUI's `overflow: hidden`
clips its own children but cannot reach into AppKit, so the canvas
painted square corners on top of the main panel's rounded edge —
the white surface visibly overshot the panel's rounded bottom.
Thread a per-corner radius through the GPUI patch:
- `Window::sync_native_surface` and the `PlatformWindow` trait carry
a `Corners<Pixels>`.
- The macOS implementation sets `CALayer.cornerRadius` to the maximum
requested radius and `maskedCorners` to the bitmask of corners that
actually requested rounding (GPUI is Y-down while NSView is Y-up,
so a GPUI "top" maps to a CALayer "MaxY" corner — comment locks
the mapping). `setMasksToBounds: YES` lets Core Animation actually
honor the corner radius for layered content.
- The `NativeSurface` element resolves all four corner radii from its
own `StyleRefinement` (so callers attach `.rounded_bl(...)` /
`.rounded_br(...)` exactly as on any other GPUI element).
Application side wires the right radius per context:
- The main canvas asks for `RADIUS_CARD` (18 px) on its bottom corners
so it follows the surrounding panel's rounded bottom edge while
the top stays flush against the toolbar.
- A split pane's canvas asks for the pane's own `SPLIT_PANE_RADIUS`
(10 px) so the canvas hugs the rounded frame the pane already paints.
`render_failed_web_surface` doesn't need rounding wiring — the error
page is a GPUI div and is clipped normally by the surrounding
`overflow: hidden`.
ZacharyZhang-NY
3678db60b9