gallery/vendor/i-slint-backend-android-activity-1.18.1/lib.rs

// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0

// cSpell: ignore androidwindowadapter javahelper
#![doc = include_str!("README.md")]
#![doc(html_logo_url = "https://slint.dev/logo/slint-logo-square-light.svg")]
#![cfg_attr(not(target_os = "android"), allow(rustdoc::broken_intra_doc_links))]
#![cfg(target_os = "android")]
#![cfg_attr(slint_nightly_test, feature(non_exhaustive_omitted_patterns_lint))]
#![cfg_attr(slint_nightly_test, warn(non_exhaustive_omitted_patterns))]

mod androidwindowadapter;
mod javahelper;
mod vsync;

pub mod stg;

#[cfg(all(not(feature = "aa-06"), feature = "aa-05"))]
pub use android_activity_05 as android_activity;
#[cfg(feature = "aa-06")]
pub use android_activity_06 as android_activity;

#[cfg(all(not(feature = "aa-06"), feature = "aa-05"))]
use ndk_08 as ndk;
#[cfg(feature = "aa-06")]
use ndk_09 as ndk;

pub use android_activity::AndroidApp;
use android_activity::PollEvent;
use androidwindowadapter::AndroidWindowAdapter;
use core::ops::ControlFlow;
use core::time::Duration;
use i_slint_core::api::{EventLoopError, PlatformError};
use i_slint_core::platform::{Clipboard, WindowAdapter};
use i_slint_renderer_skia::SkiaRendererExt;
use std::cell::RefCell;
use std::rc::{Rc, Weak};
use std::sync::{Arc, Mutex};

thread_local! {
    static CURRENT_WINDOW: RefCell<Weak<AndroidWindowAdapter>> = RefCell::new(Default::default());
}

pub struct AndroidPlatform {
    app: AndroidApp,
    window: Rc<AndroidWindowAdapter>,
    event_listener: Option<Box<dyn Fn(&PollEvent<'_>)>>,
    context: core::cell::OnceCell<i_slint_core::SlintContextWeak>,
}

impl AndroidPlatform {
    /// Instantiate a new Android backend given the [`android_activity::AndroidApp`]
    ///
    /// Pass the returned value to [`slint::platform::set_platform()`](`i_slint_core::platform::set_platform()`)
    ///
    /// # Example
    /// ```
    /// #[cfg(target_os = "android")]
    /// #[unsafe(no_mangle)]
    /// fn android_main(app: i_slint_backend_android_activity::AndroidApp) {
    ///     slint::platform::set_platform(Box::new(
    ///         i_slint_backend_android_activity::AndroidPlatform::new(app),
    ///     ))
    ///     .unwrap();
    ///     // ... your slint application ...
    /// }
    /// ```
    pub fn new(app: AndroidApp) -> Self {
        let window = AndroidWindowAdapter::new(app.clone());
        CURRENT_WINDOW.set(Rc::downgrade(&window));
        Self { app, window, event_listener: None, context: Default::default() }
    }

    /// Instantiate a new Android backend given the [`android_activity::AndroidApp`]
    /// and a function to process the events.
    ///
    /// This is the same as [`AndroidPlatform::new()`], but it allow you to get notified
    /// of events.
    ///
    /// Pass the returned value to [`slint::platform::set_platform()`](`i_slint_core::platform::set_platform()`)
    ///
    /// # Example
    /// ```
    /// #[cfg(target_os = "android")]
    /// #[unsafe(no_mangle)]
    /// fn android_main(app: i_slint_backend_android_activity::AndroidApp) {
    ///     slint::platform::set_platform(Box::new(
    ///         i_slint_backend_android_activity::AndroidPlatform::new_with_event_listener(
    ///             app,
    ///             |event| { eprintln!("got event {event:?}") }
    ///         ),
    ///     ))
    ///     .unwrap();
    ///     // ... your slint application ...
    /// }
    /// ```
    pub fn new_with_event_listener(
        app: AndroidApp,
        listener: impl Fn(&PollEvent<'_>) + 'static,
    ) -> Self {
        let mut this = Self::new(app);
        this.event_listener = Some(Box::new(listener));
        this
    }
}

impl i_slint_core::platform::Platform for AndroidPlatform {
    fn create_window_adapter(&self) -> Result<Rc<dyn WindowAdapter>, PlatformError> {
        Ok(self.window.clone())
    }
    fn run_event_loop(&self) -> Result<(), PlatformError> {
        let ctx = self
            .context
            .get()
            .and_then(|ctx| ctx.upgrade())
            .expect("the event loop runs inside the context that owns this platform");
        // 120Hz scroll fix (docs/BUGS/scroll-jank-120hz.md): enable the
        // render-ahead pipeline in the wgpu surface. It is only ACTIVE per-
        // frame while `locked` (VSYNC_LOCKED_RENDER && animating); unlocked
        // renders always present immediately. See RENDER_AHEAD / RENDER_AHEAD_ACTIVE.
        i_slint_renderer_skia::wgpu_30_surface::vkprobe::RENDER_AHEAD
            .store(true, std::sync::atomic::Ordering::Relaxed);
        let vsync = vsync::VsyncDriver::new(self.app.create_waker());
        // RENDER_AHEAD flush: tracks the previous iteration's locked state so
        // that when animation ends we do one final render() — which presents
        // the frame held by the render-ahead pipeline (otherwise the last
        // content change would never be displayed).
        let mut prev_locked = false;
        // Edge (ns) of the last vsync delivered to this thread via the
        // eventfd trampoline (vsync.rs). A value newer than this at
        // decision time means a wake was delivered THIS iteration — immune
        // to the ALooper wake-fd swallow (see vsync.rs note).
        let mut last_delivered_edge = 0u64;
        // DRIVER: the slot index (relative to the smooth grid anchor) we
        // last rendered for. One render per SLOT — the double-fire guard
        // for the grid-driven accept. Slot-index space (not edge-value
        // space): a late-callback re-anchor shifts edge VALUES by
        // ~0.2–0.5 ms and would make an already-rendered slot look new.
        let mut last_rendered_slot: i128 = i128::MIN;
        loop {
            let mut timeout = ctx.duration_until_next_timer_update();
            // While animating, the vsync thread wakes this loop at each display refresh
            // so rendering tracks the refresh rate instead of a fixed poll timeout.
            //
            // We also treat an ACTIVE POINTER DRAG as "animating" (see
            // stg::pointer_recently_active): during a direct drag Slint has no
            // physics animation, so has_active_animations() is false and, without
            // this, the loop would sleep until the next timer (16 ms) between
            // pointer events → 16-30 ms frame gaps. Keeping the vsync driver
            // alive makes poll_events wake at each display refresh instead.
            let animating = self.window.window.has_active_animations()
                || stg::pointer_recently_active();
            // Push (animating, dirty) to the vsync driver: the Choreographer
            // callback chain self-sustains while animating OR dirty
            // (vsync.rs) — the dirty leg is what keeps flings alive after
            // pointer inactivity expires the `animating` window.
            let dirty = self.window.pending_redraw.get();
            vsync.set_state(animating, dirty);
            let pr_before = self.window.pending_redraw.get();
            let locked = stg::VSYNC_LOCKED_RENDER
                .load(std::sync::atomic::Ordering::Relaxed)
                && animating;
            if locked {
                // DRIVER mode (2026-10-30): the render clock is owned by the
                // app, not the OS. The decision is grid-driven (see below) —
                // no wake required — so the poll is NON-BLOCKING (timeout 0);
                // the loop spins at ~3-4k iterations/s (a 250 µs park after
                // each no-render iteration, see end of loop) checking the
                // grid. A 250 µs hrtimer park cannot be lost the way an
                // ALooper timeout wake can (measured: poll(1) returning
                // 4-6 ms LATE from inside kernel/epoll — the residual
                // +4.5-6 ms present population of slt13), and the thread
                // stays HOT (EAS big-core placement; a sleeping thread idles
                // at 820 MHz on little cores). The Choreographer + eventfd
                // stay alive as the GRID SENSOR (VSYNC_EDGE_NS), never as
                // the render trigger.
                timeout = Some(Duration::ZERO);
            } else if animating || dirty {
                // When animating (scrolling/flinging) or dirty, cap the poll
                // timeout to 2ms. (2026-10-30: the cap was 6ms — but
                // ALooper_pollOnce(6) itself returns 2-5 ms LATE on this
                // device (measured: polls of 8.4-10.7 ms with to=6, no
                // context switches — the delay is inside kernel/epoll,
                // not app-side). One lost/late wake then ate a whole slot:
                // render start edge+6-8 ms → present edge+7-9 ms → the
                // residual 0.6% slip-frames. With a 2ms cap, even if a wake
                // is lost to a kernel delay the next poll picks it up
                // within 2 ms → render start edge+2-3 ms → present edge
                // +3-4 ms, inside the slot. Cost: ~200-400 extra idle
                // iterations/s during active scroll, each ~0.1-0.3 ms
                // (no render) ≈ a few % UI CPU. Emulator A/B (2ms vs 6ms,
                // 2026-10-30): no difference — 5-8 drops/capture both ways,
                // vs 47-147/capture for the pre-evfd build, so the evfd
                // wake-fd fix dominates and the shorter cap is kept.)
                let frame_duration = Duration::from_millis(2);
                timeout = Some(timeout.map_or(frame_duration, |x| x.min(frame_duration)));
            }
            // `request_redraw()` only raises the flag, so a request issued outside the
            // poll would otherwise wait here for an unrelated wakeup.
            // EXCEPT in vsync-locked mode: the render is deliberately deferred
            // to the vsync WAKE, so a zero timeout here would busy-spin the
            // loop at ~100 kHz (timeout event, no wake, flag never consumed)
            // for up to 8.3 ms after every input event. Block up to the cap
            // instead and let the wake arrive.
            if pr_before && !locked {
                timeout = Some(Duration::ZERO);
            }
            if pr_before && !locked {
                timeout = Some(Duration::ZERO);
            }
            // Jank-hunt: classify the timeout path to explain the 1451 iters/s
            // busy-spin. ZERO = forced by pending_redraw; CAP = 6 ms anim cap;
            // NATURAL = the next timer (>= ~7 ms).
            if stg::IT_ON.load(std::sync::atomic::Ordering::Relaxed) {
                let to_ms = timeout.map(|d| d.as_secs_f64() * 1000.0).unwrap_or(f64::MAX);
                let kind = if pr_before {
                    0
                } else if animating && to_ms <= 6.0 {
                    1
                } else {
                    2
                };
                stg::note_timeout_class(kind);
            }
            // STG (jank-hunt instrumentation): reset per-iteration marks.
            {
                let pr = stg::S_RENDER_START.load(std::sync::atomic::Ordering::Relaxed);
                let pe = stg::S_RENDER_END.load(std::sync::atomic::Ordering::Relaxed);
                if pr != 0 && pe != 0 {
                    stg::S_LAST_RENDER_US
                        .store(pe - pr, std::sync::atomic::Ordering::Relaxed);
                }
            }
            // PRE-POLL SPIN-RENDER (2026-10-31, finger-run beat fix #2):
            // the post-poll target spin alone could not pin the phase —
            // a queued finger event (1-3 ms to process) crossed the
            // edge+0.45 ms target DURING poll_events, so the spin found
            // the target already past and rendered at input-completion
            // time. Measured on the phone: phase histogram 0.4-3.0 ms
            // continuous (median 1.05) == the input-processing-duration
            // distribution, and the glass showed 10.5 ms beat gaps.
            // Fix: when the driver's target is within 1.2 ms and the slot
            // is unrendered, SKIP the poll (queued input rides to the
            // next slot, +8.3 ms — the standard vsync-locked input
            // latency, imperceptible) and spin to the exact target.
            if locked {
                let __p0 = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_PERIOD_NS
                    .load(std::sync::atomic::Ordering::Relaxed);
                let __e0 = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_EDGE_NS
                    .load(std::sync::atomic::Ordering::Relaxed);
                let __n0 = i_slint_renderer_skia::wgpu_30_surface::vkprobe::monotonic_ns();
                if __p0 != 0 && __n0 >= __e0 {
                    let __s0 = ((__n0 - __e0) as i128) / (__p0 as i128);
                    if __s0 > last_rendered_slot {
                        let __tgt = __e0 + (__s0 as u64) * __p0 + 450_000;
                        if __n0 >= __tgt - 1_200_000 {
                            while i_slint_renderer_skia::wgpu_30_surface::vkprobe::monotonic_ns() < __tgt {
                                std::thread::yield_now();
                            }
                            let __t = i_slint_renderer_skia::wgpu_30_surface::vkprobe::monotonic_ns();
                            i_slint_renderer_skia::wgpu_30_surface::vkprobe::LAST_RENDER_START_NS
                                .store(__t, std::sync::atomic::Ordering::Relaxed);
                            last_rendered_slot = __s0;
                            stg::S_START.store(stg::now_us(), std::sync::atomic::Ordering::Relaxed);
                            stg::S_FIRST_EV.store(0, std::sync::atomic::Ordering::Relaxed);
                            stg::S_TIMER_US.store(0, std::sync::atomic::Ordering::Relaxed);
                            stg::S_EVENT_US.store(0, std::sync::atomic::Ordering::Relaxed);
                            stg::S_N_EVENTS.store(0, std::sync::atomic::Ordering::Relaxed);
                            ctx.update_timers_and_animations();
                            stg::S_RENDER_START.store(stg::now_us(), std::sync::atomic::Ordering::Relaxed);
                            i_slint_renderer_skia::wgpu_30_surface::vkprobe::RENDER_AHEAD_ACTIVE
                                .store(true, std::sync::atomic::Ordering::Relaxed);
                            let __ok = self.window.do_render().is_ok();
                            stg::S_RENDER_END.store(stg::now_us(), std::sync::atomic::Ordering::Relaxed);
                            // On error (surface gone during pause/destroy)
                            // fall through instead of continuing: the
                            // normal path below re-checks state, processes
                            // the teardown events, and propagates the
                            // error via its own `do_render()?`.
                            if __ok {
                                prev_locked = locked;
                                continue;
                            }
                        }
                    }
                }
            }
            let t_start = stg::now_us();
            let timeout_ms = timeout.map(|d| d.as_millis() as u64).unwrap_or(u64::MAX);
            stg::S_START.store(t_start, std::sync::atomic::Ordering::Relaxed);
            stg::S_FIRST_EV.store(0, std::sync::atomic::Ordering::Relaxed);
            stg::S_TIMER_US.store(0, std::sync::atomic::Ordering::Relaxed);
            stg::S_EVENT_US.store(0, std::sync::atomic::Ordering::Relaxed);
            stg::S_N_EVENTS.store(0, std::sync::atomic::Ordering::Relaxed);
            let mut r = Ok(ControlFlow::Continue(()));
            // Jank-hunt / 120Hz: did this poll return because the vsync driver
            // (or any waker) fired? Used to lock rendering to the vsync edge
            // (see the render decision below) instead of rendering in reaction
            // to input events (which arrive at a random phase in the slot and
            // push the present past the ~5.5 ms compositor deadline → every
            // frame shown one vsync late → effective 60 Hz + judder).
            let mut saw_wake = false;
            // H5 (hypotheses-120hz.md): CPU time inside poll_events. wall≫cpu
            // ⇒ the UI thread slept/descheduled while the wake byte was
            // pending (epoll not woken, or the thread lost the CPU); wall≈cpu
            // ⇒ the loop spun inside ALooper.
            let __cpu_p0 = stg::thread_cpu_us();
            self.app.poll_events(timeout, |e| {
                if matches!(e, PollEvent::Wake) {
                    saw_wake = true;
                }
                if stg::S_FIRST_EV.load(std::sync::atomic::Ordering::Relaxed) == 0 {
                    stg::S_FIRST_EV
                        .store(stg::now_us(), std::sync::atomic::Ordering::Relaxed);
                }
                let t3_start = stg::now_us();
                let t3_cpu_start = stg::thread_cpu_us();
                r = self.window.process_event(&e);
                let t3_end = stg::now_us();
                let t3_cpu_end = stg::thread_cpu_us();
                let __dt3 = t3_end - t3_start;
                // Jank-hunt: count wake sources. If WAKE events dominate, the
                // loop is being woken far more often than vsync (120/s) or input,
                // which explains the 1600 iters/s busy-spin.
                match e {
                    PollEvent::Wake => { stg::WAKE_COUNT.fetch_add(1, std::sync::atomic::Ordering::Relaxed); }
                    PollEvent::Timeout => { stg::TIMEOUT_EV_COUNT.fetch_add(1, std::sync::atomic::Ordering::Relaxed); }
                    PollEvent::Main(android_activity::MainEvent::InputAvailable) => {
                        stg::INPUT_EV_COUNT.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
                    }
                    _ => {}
                }
                // Jank-hunt: identify which MainEvent variant causes the big
                // `ev` spikes (pointer input is ~2.5 ms max, so a 20 ms event
                // is something else entirely).
                if __dt3 > 5_000 && stg::IT_ON.load(std::sync::atomic::Ordering::Relaxed) {
                    let nm = match e {
                        PollEvent::Main(android_activity::MainEvent::InputAvailable) => "Input",
                        PollEvent::Main(android_activity::MainEvent::InitWindow { .. }) => "InitWin",
                        PollEvent::Main(android_activity::MainEvent::TerminateWindow { .. }) => "TermWin",
                        PollEvent::Main(android_activity::MainEvent::WindowResized { .. }) => "WinResized",
                        PollEvent::Main(android_activity::MainEvent::RedrawNeeded { .. }) => "RedrawNeeded",
                        PollEvent::Main(_) => "Main-other",
                        _ => "NonMain",
                    };
                    stg::log_slow_event(nm, __dt3, t3_cpu_end.saturating_sub(t3_cpu_start));
                }
                stg::S_EVENT_US.fetch_add(__dt3, std::sync::atomic::Ordering::Relaxed);
                stg::S_N_EVENTS.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
                if let Some(event_listener) = &self.event_listener {
                    event_listener(&e)
                }
            });
            let t_poll1 = stg::now_us();
            let __poll_cpu = stg::thread_cpu_us().saturating_sub(__cpu_p0);
            let lv1 = stg::lv_snapshot();
            // Wake-fd-race fix (2026-10-30): the ALooper wake byte can be
            // CONSUMED by Looper::pollInner while pollOnce returns a
            // co-batched input ident (system/core/libutils/Looper.cpp — the
            // POLL_WAKE result is a dropped local; see vsync.rs). The
            // dedicated eventfd trampoline runs inside poll_events and
            // publishes the delivered edge there — check it NOW, after.
            let __delivered = vsync.take_delivered_edge();
            if __delivered > last_delivered_edge {
                saw_wake = true;
                last_delivered_edge = __delivered;
            }

            // Unconditionally update timers and animations on every event-loop wakeup
            ctx.update_timers_and_animations();
            let t2 = stg::now_us();
            stg::S_TIMER_US.store(t2 - t_poll1, std::sync::atomic::Ordering::Relaxed);

            stg::S_POLL_END.store(t2, std::sync::atomic::Ordering::Relaxed);
            if r?.is_break() {
                break;
            }
            let mut render_us = 0u64;
            let mut __render_cpu = 0u64;
            // Jank-hunt / 120Hz: vsync-locked rendering (the native-Android
            // model). While animating, input events only MARK the window dirty;
            // the render happens on the next vsync WAKE, so every present
            // starts at a deterministic phase (vsync edge + wake latency) and
            // lands well inside the compositor's ~5.5 ms deadline. Cost: up
            // to one slot of extra input latency.
            let do_render = if locked {
                // Present EVERY vsync while animating (not only on content
                // change): the regular 120 Hz present stream locks the
                // display cadence. Re-rendering unchanged content is cheap
                // with Skia's incremental pipeline.
                //
                // IMPORTANT: do NOT `pending_redraw.take()` here. The render
                // is driven by the vsync wake, but the pending flag also
                // carries the motion events' invalidations. Consuming it
                // here starves the follow-up unlocked iteration (which runs
                // 0.4 ms later, before the next motion event arrives) of
                // anything to render, collapsing the cadence to 60 Hz
                // (one render per two vsyncs). Letting the flag survive
                // means the next iteration renders too; if the content is
                // unchanged the extra render is invisible.
                //
                // SLOT-BASED WAKE GUARD (hypotheses-120hz.md, 2026-07-09 (3)).
                // Replaces the interval freshness guard, which had a 0.2 ms
                // false-reject margin (threshold 6.83 ms vs earliest
                // legitimate interval 7.03 ms after a Choreographer-phase
                // render) and — worse — could not express the real rule.
                // The rule: at most ONE render per display slot. A wake
                // belongs to slot floor((t − E)/P) (E = last observed vsync
                // edge, P = period; a stale E only shifts all indices by a
                // constant, so the comparison is exact). Reject only when
                // the wake's slot is the one already rendered; a wake N
                // slots later (after a spike or lost wakes) MUST render —
                // and the gap is logged as MISS with the wake state, which
                // is the missing evidence for the stall slots.
                let __now_ns = i_slint_renderer_skia::wgpu_30_surface::vkprobe::monotonic_ns();
                let __p = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_PERIOD_NS
                    .load(std::sync::atomic::Ordering::Relaxed);
                let __e = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_EDGE_NS
                    .load(std::sync::atomic::Ordering::Relaxed);
                let __last = i_slint_renderer_skia::wgpu_30_surface::vkprobe::LAST_RENDER_START_NS
                    .load(std::sync::atomic::Ordering::Relaxed);
                let __slot = |t: u64| -> i128 {
                    if t >= __e { ((t - __e) as i128) / (__p as i128) }
                    else { -((( __e - t) as i128 + __p as i128 - 1) / (__p as i128)) }
                };
                let __sw = if __p == 0 { 0 } else { __slot(__now_ns) };
                let __sn = if __p == 0 || __last == 0 { i128::MIN } else { __slot(__last) };
                if __p != 0 && __last != 0 && __sw >= __sn + 2
                    && stg::IT_ON.load(std::sync::atomic::Ordering::Relaxed)
                {
                    stg::log_miss(__sw - __sn - 1, saw_wake, __now_ns,
                        __sw, __sn,
                        __now_ns.saturating_sub(__e) / 1000,
                        __now_ns.saturating_sub(__last) / 1000);
                }
                // DIRTY BACKSTOP (2026-10-30): if the window is dirty and
                // the last render is >=2 slots old, render NOW regardless
                // of wake state (bounds any grid/sensor outage).
                let __dirty = self.window.pending_redraw.get();
                let __age = __now_ns.saturating_sub(__last);
                let __backstop = __dirty && __last != 0 && __p != 0 && __age >= 2 * __p;
                // DRIVER (2026-10-30): the APP owns the render clock. Accept
                // when we are in a slot we have not rendered yet AND at
                // least 0.3 ms past that slot's edge. No saw_wake: the 1 ms
                // micro-park keeps `now` within ~1.3 ms of the grid, so the
                // present (render-ahead, at render start) lands at
                // edge+~1.5 ms with ~6.8 ms of latch margin, every frame,
                // regardless of Choreographer/wake delivery. The grid is the
                // SMOOTH anchor (note_vsync_edge: a late callback that fits
                // the extrapolation does not move it), so the slot index
                // here is stable across late callbacks — one render per
                // slot, never a double. A render overrun lands the next
                // slot one slot late. If the grid is dead (__p==0 or
                // __now < __e) the driver is off and the saw_wake path
                // governs.
                let __ph = if __p != 0 && __now_ns >= __e {
                    (__now_ns - __e) % __p
                } else {
                    0
                };
                let __driver = __p != 0 && __now_ns >= __e + 300_000
                    && __ph >= 300_000 && __sw > last_rendered_slot;
                let __wake_ok = saw_wake && (__p == 0 || __sw > __sn);
                let __accept = __driver || __wake_ok || __backstop;
                if __accept {
                    // PRESENT TARGET (2026-10-30, finger-run beat fix):
                    // firing at the FIRST opportunity (now >= edge+0.3ms)
                    // makes the present phase = whatever the 250us park +
                    // the finger's 120-240 Hz input events (1-3 ms each)
                    // left us — measured: phase p10-p90 1.23 ms, 1019
                    // phase-jumps>0.5ms in one finger run, and the glass
                    // showed 10.5 ms inter-frame gaps (a 2 ms beat) 20
                    // times in 11 s. Instead: spin to the EXACT target
                    // (this slot's edge + 0.45 ms) before rendering. The
                    // spin is bounded (<= ~1.2 ms from detection, a
                    // sched_yield loop), and the present phase becomes
                    // edge+0.45ms +/- ~50 us — constant, no beat, no
                    // matter when the input events arrive. The wake path
                    // already lands at ~edge+0.5 (the wake's own phase),
                    // so only the driver path needs the target.
                    if __driver {
                        let __slot_edge = __e + (__sw as u64) * __p;
                        let __target = __slot_edge + 450_000;
                        while i_slint_renderer_skia::wgpu_30_surface::vkprobe::monotonic_ns() < __target {
                            std::thread::yield_now();
                        }
                    }
                    i_slint_renderer_skia::wgpu_30_surface::vkprobe::LAST_RENDER_START_NS
                        .store(__now_ns, std::sync::atomic::Ordering::Relaxed);
                    if __sw > last_rendered_slot {
                        last_rendered_slot = __sw;
                    }
                }
                __accept
            } else {
                self.window.pending_redraw.get()
            };
            if do_render {
                // Locked (vsync-wake) renders leave the flag set so the
                // follow-up unlocked iteration renders too (60 Hz collapse,
                // see the do_render note); unlocked renders consume it.
                if !locked {
                    self.window.pending_redraw.take();
                    // Unlocked renders participate in the slot bookkeeping
                    // too: without this, a locked→unlocked flicker mid-drag
                    // leaves last_rendered_slot stale and the re-locked
                    // driver re-renders the slot the unlocked render just
                    // painted (double-present).
                    let __t =
                        i_slint_renderer_skia::wgpu_30_surface::vkprobe::monotonic_ns();
                    i_slint_renderer_skia::wgpu_30_surface::vkprobe::LAST_RENDER_START_NS
                        .store(__t, std::sync::atomic::Ordering::Relaxed);
                    let __p = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_PERIOD_NS
                        .load(std::sync::atomic::Ordering::Relaxed);
                    let __e = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_EDGE_NS
                        .load(std::sync::atomic::Ordering::Relaxed);
                    if __p != 0 && __t >= __e {
                        let s = ((__t - __e) as i128) / (__p as i128);
                        if s > last_rendered_slot {
                            last_rendered_slot = s;
                        }
                    }
                }
                // RENDER_AHEAD (hold-without-present) is DISABLED: the held
                // frame is presented at the start of the NEXT render, i.e.
                // after the next vsync wake's Choreographer latency
                // (measured 3.2–6 ms on this device) plus the present cost —
                // landing at vsync+12.4–15.2 ms against a 13.8 ms latch
                // deadline: a 1.4 ms margin that missed 52% of frames
                // (one slot late) during real slow scrolls. Presenting at
                // the END of the render instead still left 51% one slot
                // late — under the model THEN believed (callback 3-6 ms
                // late). That model was WRONG: the callback fires at
                // edge+0.5 ms (measured, VSYNC mon−ftn). See
                // docs/BUGS/hypotheses-120hz.md.
                //
                // RENDER-AHEAD (re-enabled under the corrected model): the
                // wake arrives ON the edge, so the held frame — presented
                // at the START of this render — lands at edge+~1.5 ms:
                // constant phase, ~4 ms of deadline margin, and render
                // SPIKES (Skia 5-10 ms) stop delaying visible frames: a
                // spike only stretches the PREPARE phase of the frame held
                // for the NEXT slot (presented at the NEXT edge+1.5 ms,
                // same phase). Cost: one slot of constant latency
                // (imperceptible).
                i_slint_renderer_skia::wgpu_30_surface::vkprobe::RENDER_AHEAD_ACTIVE
                    .store(locked, std::sync::atomic::Ordering::Relaxed);
                // PRESENT GATE: DISABLED (UI-thread sleep ate the slot
                // budget — history in hypotheses-120hz.md). Reference only.
                i_slint_renderer_skia::wgpu_30_surface::vkprobe::PRESENT_GATE_ON
                    .store(false, std::sync::atomic::Ordering::Relaxed);
                stg::S_RENDER_START.store(t2, std::sync::atomic::Ordering::Relaxed);
                // Spike classifier (hypotheses-120hz.md): CPU time inside
                // do_render. rcpu≈render ⇒ Skia/wgpu CPU work; rcpu≪render ⇒
                // blocked on the GPU/driver (queue back-pressure, fences).
                let __rc0 = stg::thread_cpu_us();
                self.window.do_render()?;
                let t3 = stg::now_us();
                stg::S_RENDER_END.store(t3, std::sync::atomic::Ordering::Relaxed);
                render_us = t3 - t2;
                __render_cpu = stg::thread_cpu_us().saturating_sub(__rc0);
            } else {
                stg::S_RENDER_END.store(0, std::sync::atomic::Ordering::Relaxed);
            }
            // RENDER_AHEAD flush (see above): on the locked → unlocked
            // transition, render once more to present the held frame —
            // EXCEPT when this iteration already rendered (unlocked, dirty):
            // that render presented the latest content immediately, so the
            // flush would only double-present the slot. (2026-10-30: this
            // double fired on every animating-flicker during bursty drags.)
            let mut flushed_now = false;
            if prev_locked && !locked && !do_render {
                self.window.pending_redraw.take();
                i_slint_renderer_skia::wgpu_30_surface::vkprobe::RENDER_AHEAD_ACTIVE
                    .store(false, std::sync::atomic::Ordering::Relaxed);
                self.window.do_render()?;
                // Bookkeeping (2026-10-30): the flush render presents the
                // current slot; without marking it, the re-locked driver
                // re-renders the same slot ~1 ms later (the +1.1/+1.2
                // double-presents of slt13).
                let __t = i_slint_renderer_skia::wgpu_30_surface::vkprobe::monotonic_ns();
                i_slint_renderer_skia::wgpu_30_surface::vkprobe::LAST_RENDER_START_NS
                    .store(__t, std::sync::atomic::Ordering::Relaxed);
                let __p = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_PERIOD_NS
                    .load(std::sync::atomic::Ordering::Relaxed);
                let __e = i_slint_renderer_skia::wgpu_30_surface::vkprobe::VSYNC_EDGE_NS
                    .load(std::sync::atomic::Ordering::Relaxed);
                if __p != 0 && __t >= __e {
                    let s = ((__t - __e) as i128) / (__p as i128);
                    if s > last_rendered_slot {
                        last_rendered_slot = s;
                    }
                }
                flushed_now = true;
            }
            // DRIVER spin throttle (2026-10-30): see the timeout note. After
            // a no-render locked iteration, park 250 µs (hrtimer — cannot be
            // swallowed like an ALooper timeout) so the grid is re-checked
            // within ~0.3 ms of each edge.
            if locked && !do_render && !flushed_now {
                std::thread::sleep(Duration::from_micros(250));
            }
            prev_locked = locked;
            // Miss forensics (CONDITIONAL — 2026-07-09): the per-iteration
            // /proc read was itself a confounder (procfs reads cost tens of
            // µs on the UI thread; with render completion near the slot
            // boundary that pushed the present phase across it — 10x worse
            // drops/doubles measured). Sample only around SLOW iterations
            // (>5 ms wall): those are exactly the miss candidates, and the
            // common path pays nothing.
            let __iter_wall = stg::now_us().saturating_sub(t_start);
            let (__vsw, __nvol):
                (u64, u64) = if __iter_wall > 5_000 && stg::IT_ON.load(std::sync::atomic::Ordering::Relaxed)
            {
                // Delta against the rolling baseline (previous slow sample).
                let c = stg::ctxsw_sample();
                let pv = stg::CTX_PREV_V.load(std::sync::atomic::Ordering::Relaxed);
                let pn = stg::CTX_PREV_NV.load(std::sync::atomic::Ordering::Relaxed);
                let first = !stg::CTX_SAMPLED.swap(true, std::sync::atomic::Ordering::Relaxed);
                stg::CTX_PREV_V.store(c.0, std::sync::atomic::Ordering::Relaxed);
                stg::CTX_PREV_NV.store(c.1, std::sync::atomic::Ordering::Relaxed);
                if first { (0, 0) } else { (c.0.saturating_sub(pv), c.1.saturating_sub(pn)) }
            } else {
                (0, 0)
            };
            if stg::IT_ON.load(std::sync::atomic::Ordering::Relaxed) {
                let first_ev = stg::S_FIRST_EV.load(std::sync::atomic::Ordering::Relaxed);
                let lv2 = stg::lv_snapshot();
                stg::log_iter(
                    t_start,
                    t_poll1 - t_start,
                    stg::S_N_EVENTS.load(std::sync::atomic::Ordering::Relaxed),
                    if first_ev == 0 { 0 } else { first_ev - t_start },
                    t2 - t_poll1,
                    stg::S_EVENT_US.load(std::sync::atomic::Ordering::Relaxed),
                    render_us,
                    animating,
                    timeout_ms,
                    lv1,
                    lv2,
                    stg::flick_snapshot(),
                    stg::input_snapshot(),
                    stg::timeout_snapshot(),
                    stg::wake_snapshot(),
                    (locked, saw_wake, pr_before, do_render),
                    __poll_cpu,
                    __render_cpu,
                    __vsw,
                    __nvol,
                );
            }
        }
        Ok(())
    }

    fn new_event_loop_proxy(&self) -> Option<Box<dyn i_slint_core::platform::EventLoopProxy>> {
        Some(Box::new(AndroidEventLoopProxy {
            event_queue: self.window.event_queue.clone(),
            waker: self.app.create_waker(),
        }))
    }

    fn set_clipboard_text(&self, text: &str, clipboard: Clipboard) {
        if clipboard == Clipboard::DefaultClipboard {
            self.window
                .java_helper
                .set_clipboard(text)
                .unwrap_or_else(|e| javahelper::print_jni_error(&self.app, e));
        }
    }

    fn clipboard_text(&self, clipboard: Clipboard) -> Option<String> {
        if clipboard == Clipboard::DefaultClipboard {
            Some(
                self.window
                    .java_helper
                    .get_clipboard()
                    .unwrap_or_else(|e| javahelper::print_jni_error(&self.app, e)),
            )
        } else {
            None
        }
    }

    fn bind_context(&self, ctx: i_slint_core::SlintContextWeak, _: i_slint_core::InternalToken) {
        let _ = self.context.set(ctx.clone());
        let ctx = ctx.upgrade().expect("bind_context called while the SlintContext is still alive");
        let color_scheme = match self
            .window
            .java_helper
            .color_scheme()
            .unwrap_or_else(|e| javahelper::print_jni_error(&self.app, e))
        {
            0x10 => i_slint_core::items::ColorScheme::Light, // UI_MODE_NIGHT_NO
            0x20 => i_slint_core::items::ColorScheme::Dark,  // UI_MODE_NIGHT_YES
            _ => i_slint_core::items::ColorScheme::Unknown,
        };
        ctx.set_color_scheme(color_scheme);
        if let Ok(accent) = self.window.java_helper.accent_color() {
            ctx.set_accent_color(accent);
        }
        if let Ok(scale) = self.window.java_helper.font_scale()
            && let Some(size) = javahelper::font_scale_to_logical_length(scale)
        {
            ctx.set_platform_default_font_size(Some(size));
        }
    }

    fn long_press_interval(&self, _: i_slint_core::InternalToken) -> Duration {
        self.window.java_helper.long_press_timeout().unwrap_or(Duration::from_millis(500))
    }
}

enum Event {
    Quit,
    Other(Box<dyn FnOnce() + Send + 'static>),
}

type EventQueue = Arc<Mutex<Vec<Event>>>;

struct AndroidEventLoopProxy {
    event_queue: EventQueue,
    waker: android_activity::AndroidAppWaker,
}

impl i_slint_core::platform::EventLoopProxy for AndroidEventLoopProxy {
    fn quit_event_loop(&self) -> Result<(), EventLoopError> {
        self.event_queue.lock().unwrap().push(Event::Quit);
        self.waker.wake();
        Ok(())
    }

    fn invoke_from_event_loop(
        &self,
        event: Box<dyn FnOnce() + Send>,
    ) -> Result<(), EventLoopError> {
        let n = crate::stg::INVK_PUSH_COUNT.fetch_add(1, std::sync::atomic::Ordering::Relaxed) + 1;
        crate::stg::log_line(&format!("INVK n={n}"));
        self.event_queue.lock().unwrap().push(Event::Other(event));
        self.waker.wake();
        Ok(())
    }
}

pub fn set_requested_graphics_api(
    requested_graphics_api: Option<i_slint_core::graphics::RequestedGraphicsAPI>,
) -> Result<(), PlatformError> {
    let Some(adapter) = CURRENT_WINDOW.with_borrow(|x| x.upgrade()) else {
        return Err(format!("On Android a graphics API for Slint can only be requested after calling slint::android::init()").into());
    };
    adapter.set_requested_graphics_api(requested_graphics_api);
    Ok(())
}