Two T10-flavoured changes in one commit, each independently ship-able
on its own:
1. `web_surface_frame::rgba_hash` switches from std's
`DefaultHasher` (SipHash13, ~1.5 GB/s) to `ahash::AHasher`
(~10 GB/s). At 1080p (8 MB per frame) the dedup key drops from
~5 ms to ~0.8 ms per cache-miss frame, returning roughly 25 % of
the 16 ms scroll budget that was being spent hashing the
newly-arrived RGBA payload. ahash was already in the dependency
graph transitively via hashbrown, so this only adds a direct
`ahash = "0.8"` line and one Cargo.lock entry.
2. `docs/t10-iosurface-plan.md` records the full architectural
roadmap for the actual zero-copy path that supersedes the
software-pipe pipeline: `OffscreenRenderingContext` against a
hardware surfman adapter, IOSurface-backed surface on macOS,
mach-port handoff to the GPUI process, MTLTexture import as an
external sampler. The document explains why each currently
shipped commit (`840255f`, `a80d039`, `e02c0fd`, `7f3b8b4`, plus
this hash swap) is a stepping stone that eventually deletes
itself once the IOSurface path lands, and names the upstream
API gap in `servo-paint-api` that blocks step 2.
cargo test --bin ely_app: 120 passed, 0 failed, 2 ignored.
Hash collision probability remains ~1 in 2^64; AHash uses the same
keyspace as the previous SipHash13.
A GPUI harness boots a real ElyShell, navigates to an external URL, and
asks the input_overlay's sibling canvas tracker where it laid out. On
main before this change the canvas reports
Bounds { origin: (309, window_height - 17), size: (W - 326, content_h) }
i.e. the overlay's top edge sits at the very bottom of the visible
window. Every user click in the visible area lands above (or beside)
the overlay; the on_mouse_down + capture_any_mouse_up listeners never
even see the event because the hitbox is off-screen. Twelve commits
chased focus/coords/outcome enums on the sidecar side while every click
in the live shell hit empty space.
Root cause: in render_web_surface the rendered web image (img / loading
div / error page) was a non-absolute child of a `.relative().size_full()`
wrapper. The non-absolute child claims `size_full` block-flow height
inside that wrapper, which made the wrapper's intrinsic height
content_height + content_height. The two `.absolute().size_full()`
siblings (viewport_tracker, input_overlay) then sized against that
inflated parent and were positioned in the bottom half — exactly
content_height below where they were supposed to be.
Fix: keep the relative wrapper as the layout owner of the panel slot
(size_full, overflow_hidden, min_w_0) and put the rendered image into
an absolute `inset_0` child of its own. viewport_tracker and
input_overlay stay as absolute siblings. With the image out of in-flow
the wrapper sizes to its parent and the overlay's hitbox lands at
y = top of content area (71 in a 1080-tall window) instead of
y = window_height - 17.
GPUI test harness (`gpui_harness_tests.rs`) is the holdout set:
- `baseline_overlay_div_receives_simulated_click` proves GPUI's
occlude + capture_any_mouse_up primitive works under TestAppContext.
- `baseline_overlay_with_full_listener_combo_receives_click` proves
the exact listener combo render_input_overlay uses works in
isolation.
- `ely_shell_external_canvas_lays_out_inside_window` boots a real
ElyShell, navigates, and asserts the overlay's measured bounds fit
inside the visible window. Without the fix above, this test trips
on bounds extending below the window bottom.
The three new store-layer tests in web_surface_tests.rs pin per-tab
isolation, zero-delta short-circuit, and resize-mid-drain decoupling
invariants the harness work flushed out.
ely_app picks up gpui's test-support feature as a dev-dependency so the
harness can use VisualTestContext + simulate_mouse_*.
cargo test --bin ely_app: 112 passed (was 108 + 4 new harness/store tests).
Remaining work (not in this commit): even with the layout fixed, the
harness shows MouseUp's capture_any_mouse_up still doesn't fire on the
ElyShell tree, while MouseDown's bubble does. Some sibling/ancestor
listener in the live shell is eating the MouseUp capture phase that
the standalone listener-combo baseline does not. Tracked separately.
ZacharyZhang-NY