edde746
644c782edd
The 1x1 keep-alive repaint loop was extended to Windows in a87aa296 to
paper over the legacy compositing path's resize desync (#227); the DComp
rework replaced that presentation path entirely. On the DComp engine the
100ms repaints become DirectComposition commits during playback, and
once fullscreen focus engages VRR (FreeSync/G-Sync) every commit forces
a scanout off the video's cadence - the micro-stutter of #1707.
The widget now owns the platform decision behind a test seam, and a new
quiescence test pins the hidden-chrome player UI to zero scheduled
frames so no future ticker can silently reintroduce the defect.
62 lines
2.0 KiB
Dart
62 lines
2.0 KiB
Dart
import 'dart:async' show Timer;
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import 'dart:io' show Platform;
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import 'package:flutter/material.dart';
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/// A 1x1 pixel widget that continuously repaints to keep Flutter's frame clock
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/// active on Linux, where GTK's frame clock goes idle and freezes animations.
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///
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/// Linux-only by design. Mounting this on other platforms is harmful: on
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/// Windows the 10Hz repaints become DirectComposition commits during playback,
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/// and once fullscreen focus engages VRR (FreeSync/G-Sync) each commit forces a
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/// scanout off the video's cadence — the micro-stutter of issue #1707. Every
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/// non-Linux platform must instead uphold the invariant that the player UI
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/// schedules no frames while its chrome is hidden.
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class LinuxKeepAlive extends StatefulWidget {
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const LinuxKeepAlive({super.key});
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/// Forces the platform decision so tests can exercise both the ticking and
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/// the inert path regardless of host OS.
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@visibleForTesting
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static bool? debugIsLinuxOverride;
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/// Whether this widget repaints on the current platform. Exposed so the
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/// quiescence test can pin the policy to exactly [Platform.isLinux].
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@visibleForTesting
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static bool get ticksOnThisPlatform => debugIsLinuxOverride ?? Platform.isLinux;
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@override
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State<LinuxKeepAlive> createState() => _LinuxKeepAliveState();
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}
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class _LinuxKeepAliveState extends State<LinuxKeepAlive> {
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Timer? _timer;
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int _tick = 0;
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@override
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void initState() {
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super.initState();
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if (!LinuxKeepAlive.ticksOnThisPlatform) return;
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// Repaint every 100ms to keep Flutter's frame scheduler active.
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_timer = Timer.periodic(const Duration(milliseconds: 100), (_) {
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if (mounted) {
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setState(() {
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_tick++;
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});
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}
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});
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}
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@override
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void dispose() {
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_timer?.cancel();
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super.dispose();
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}
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@override
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Widget build(BuildContext context) {
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if (_timer == null) return const SizedBox.shrink();
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return SizedBox(width: 1, height: 1, child: ColoredBox(color: Color.fromRGBO(0, 0, 0, _tick % 2 == 0 ? 0.1 : 0.2)));
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}
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}
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