scheduler library

The Flutter Scheduler library.

To use, import package:flutter/scheduler.dart.

This library is responsible for scheduler frame callbacks, and tasks at given priorities.

The library makes sure that tasks are only run when appropriate. For example, an idle-task is only executed when no animation is running.

Classes

DiagnosticsNode: Defines diagnostics data for a value.
FrameTiming: Time-related performance metrics of a frame.
PerformanceModeRequestHandle: An opaque handle that keeps a request for DartPerformanceMode active until disposed.
Priority: A task priority, as passed to SchedulerBinding.scheduleTask.
Ticker: Calls its callback once per animation frame, when enabled.
TickerFuture: An object representing an ongoing Ticker sequence.
TickerProvider: An interface implemented by classes that can vend Ticker objects.

AppLifecycleState: States that an application can be in once it is running.
SchedulerPhase: The various phases that a SchedulerBinding goes through during SchedulerBinding.handleBeginFrame.
SchedulerServiceExtensions: Service extension constants for the scheduler library.

debugPrintBeginFrameBanner ↔ bool: Print a banner at the beginning of each frame.
getter/setter pair
debugPrintEndFrameBanner ↔ bool: Print a banner at the end of each frame.
getter/setter pair
debugPrintScheduleFrameStacks ↔ bool: Log the call stacks that cause a frame to be scheduled.
getter/setter pair
debugTracePostFrameCallbacks ↔ bool: Record timeline trace events for post-frame callbacks.
getter/setter pair
timeDilation ↔ double: Slows down animations by this factor to help in development.
getter/setter pair

debugAssertAllSchedulerVarsUnset(String reason) → bool: Returns true if none of the scheduler library debug variables have been changed.
defaultSchedulingStrategy({required int priority, required SchedulerBinding scheduler}) → bool: The default SchedulingStrategy for SchedulerBinding.schedulingStrategy.

FrameCallback = void Function(Duration timeStamp): Signature for frame-related callbacks from the scheduler.
SchedulingStrategy = bool Function({required int priority, required SchedulerBinding scheduler}): Signature for the SchedulerBinding.schedulingStrategy callback. Called whenever the system needs to decide whether a task at a given priority needs to be run.
TaskCallback<T> = FutureOr<T> Function(): Signature for SchedulerBinding.scheduleTask callbacks.
TickerCallback = void Function(Duration elapsed): Signature for the callback passed to the Ticker class's constructor.
TimingsCallback = void Function(List<FrameTiming> timings): Signature for PlatformDispatcher.onReportTimings.
VoidCallback = void Function(): Signature of callbacks that have no arguments and return no data.

TickerCanceled: Exception thrown by Ticker objects on the TickerFuture.orCancel future when the ticker is canceled.