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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:flutter/foundation.dart';
/// A task priority, as passed to [SchedulerBinding.scheduleTask].
@immutable
class Priority {
const Priority._(this._value);
/// Integer that describes this Priority value.
int get value => _value;
final int _value;
/// A task to run after all other tasks, when no animations are running.
static const Priority idle = Priority._(0);
/// A task to run even when animations are running.
static const Priority animation = Priority._(100000);
/// A task to run even when the user is interacting with the device.
static const Priority touch = Priority._(200000);
/// Maximum offset by which to clamp relative priorities.
///
/// It is still possible to have priorities that are offset by more
/// than this amount by repeatedly taking relative offsets, but that
/// is generally discouraged.
static const int kMaxOffset = 10000;
/// Returns a priority relative to this priority.
///
/// A positive [offset] indicates a higher priority.
///
/// The parameter [offset] is clamped to ±[kMaxOffset].
Priority operator +(int offset) {
if (offset.abs() > kMaxOffset) {
// Clamp the input offset.
offset = kMaxOffset * offset.sign;
}
return Priority._(_value + offset);
}
/// Returns a priority relative to this priority.
///
/// A positive offset indicates a lower priority.
///
/// The parameter [offset] is clamped to ±[kMaxOffset].
Priority operator -(int offset) => this + (-offset);
}