lab/ux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

insets: lazy _start capture matches frame-callback ts domain

Browse Source 
`_start` was assigned from `currentSystemFrameTimeStamp` (raw,
since-boot) while the frame callback's `ts` parameter is
epoch-adjusted (since the binding's first observed frame). The two
live in different time domains; `dt = (ts - _start) / animDuration`
came out massively negative, `clamp(0, 1)` pinned `t = 0`, and
`_current` never moved past `_from` no matter how many frames fired.

The bug was masked on most flows because `_current` happened to
coincide with the post-animation target value already, but it
surfaced on Android EMUI 12 after dismissing a gallery from a
keyboard-open chat: the bottom inset stayed at 0 instead of
animating back to the nav-bar height, leaving the composer flush
with the screen edge and the system nav bar painted on top of it.
Opening the keyboard again forced an unrelated metric pump that
finally drove `_tick` to completion.

Fix: capture `_start` lazily from the first `_tick`'s `ts`, so both
sides of the subtraction live in the same epoch-adjusted domain.

Regression test asserts viewPadding advances past `_from` across
pumped frames; pre-fix it stayed at 0.
This commit is contained in:
agra
2026-05-29 08:40:19 +03:00
parent 4fa46725a9
commit 2398c8ad35
2 changed files with 54 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
lib/src/view_padding.dart
View File

@@ -33,7 +33,10 @@ class XInsets with ChangeNotifier, WidgetsBindingObserver {
EdgeInsets _system = EdgeInsets.zero;
EdgeInsets _current = EdgeInsets.zero;
EdgeInsets _from = EdgeInsets.zero;
Duration _start = Duration.zero;
// Lazy: captured on the first _tick of an animation so the value lives in
// the same time domain as the frame-callback `ts` parameter (epoch-adjusted),
// not the raw `currentSystemFrameTimeStamp` which is since-boot.
Duration? _start;
bool _ticking = false;
Duration? _nextAnimationDuration;
@@ -77,19 +80,18 @@ class XInsets with ChangeNotifier, WidgetsBindingObserver {
}
_from = _current;
_animDuration = animDuration;
_start = SchedulerBinding.instance.currentSystemFrameTimeStamp;
if (!_ticking) {
_ticking = true;
SchedulerBinding.instance.scheduleFrameCallback(_tick);
SchedulerBinding.instance.scheduleFrame();
}
_start = null;
_ticking = true;
SchedulerBinding.instance.scheduleFrameCallback(_tick);
SchedulerBinding.instance.scheduleFrame();
}
Duration _animDuration = Duration.zero;
void _tick(Duration ts) {
if (!_ticking) return;
final dt = (ts - _start).inMicroseconds / _animDuration.inMicroseconds;
_start ??= ts;
final dt = (ts - _start!).inMicroseconds / _animDuration.inMicroseconds;
final t = curve.transform(dt.clamp(0.0, 1.0));
_current = EdgeInsets.lerp(_from, _system, t)!;
notifyListeners();
@@ -98,6 +100,7 @@ class XInsets with ChangeNotifier, WidgetsBindingObserver {
SchedulerBinding.instance.scheduleFrame();
} else {
_ticking = false;
_start = null;
}
}