smix-screen

Accessibility tree types for iOS-Simulator automation — A11yNode, Rect, Bounds, Role, ElementSummary, ScreenDescription — with inlined visibility primitives that approach single-cycle latency on M-series machines.

Zero-allocation arithmetic, #[inline] on the hot path, criterion bench medians available below for reference. The visibility math is the same semantics maestro and Apple's XCUITest enforce (any non-empty frame intersection with the viewport, zero-width / zero-height bounds short-circuit to false).

Quickstart

use smix_screen::{
    A11yNode, Rect, Role, collect_visible_summaries, is_visible_enough,
    summarize_node, visible_area,
};

let node = A11yNode {
    raw_type: "button".into(),
    role: Some(Role::Button),
    identifier: Some("btn-login".into()),
    label: Some("Log in".into()),
    title: None, placeholder_value: None, value: None, text: None,
    bounds: Rect { x: 50.0, y: 100.0, w: 200.0, h: 40.0 },
    enabled: true, selected: false, has_focus: false, visible: true,
    children: vec![],
};
let viewport = Rect { x: 0.0, y: 0.0, w: 390.0, h: 844.0 };
let tree = A11yNode {
    raw_type: "application".into(),
    bounds: viewport,
    children: vec![node.clone()],
    ..node.clone()
};

assert!(is_visible_enough(&node, &tree));
assert_eq!(visible_area(&node, &tree), 200.0 * 40.0);

let summary = summarize_node(&node);
assert_eq!(summary.name.as_deref(), Some("Log in"));

let summaries = collect_visible_summaries(&tree, 100);
assert_eq!(summaries.len(), 2); // root + button

Performance (criterion bench medians on M-series macOS)

Operation	TS V8 baseline	`smix-screen` Rust	Speedup
`is_visible_enough` (in-view)	21.2 ns	0.996 ns	21×
`is_visible_enough` (zero-bounds early reject)	20.5 ns	0.449 ns	46×
`is_visible_enough` (unknown-root conservative pass)	20.6 ns	0.584 ns	35×
`is_visible_enough` (offscreen)	20.7 ns	0.805 ns	26×
`visible_area` (intersection arithmetic)	20.9 ns	1.112 ns	19×
`dfs_collect` 100-node composite	788 ns	233 ns	3.4×

Numbers reproducible via cargo bench --bench visibility -p smix-screen.

When to reach for this

Use case	Pick
Need typed `A11yNode` matching Apple's XCUIElement attribute set	smix-screen
Need to filter "visible enough" candidates on a hot path	smix-screen
Want the same visibility semantics as maestro / XCUITest `.isHittable`	smix-screen
Need a full DOM/HTML accessibility tree (browser context)	use a browser-focused crate; this is iOS-shaped
Need physical device a11y tree	this is sim-shaped (camelCase wire fields match `xcrun simctl io` outputs)

Wire compatibility

JSON serialization uses serde(rename_all = "camelCase") matching the iOS-Simulator runner conventions: rawType, placeholderValue, hasFocus. children: Vec<A11yNode> is recursive; terminal nodes may omit the field (serde default = "...").

The Role enum mirrors XCUIElement.ElementType literals (29 variants) with a stable camelCase wire name accessor (Role::Button.as_str() → "button").

Scope

✅ Pure types + visibility primitives
✅ #[inline] + zero-allocation hot path
✅ camelCase JSON wire matches the iOS sim runner format
✅ ScreenDescription + collect_visible_summaries for DFS-pre-order visible-element projection
❌ No tree fetch (use smix-runner-client for the HTTP IPC)
❌ No selector parsing (use smix-selector)
❌ No resolver / spatial filter logic (use smix-selector-resolver)

License

Dual-licensed under either:

at your option.