Tokamak/Sources/TokamakDOM/App/ScenePhaseObserver.swift

37 lines
1.2 KiB
Swift

// Copyright 2020-2021 Tokamak contributors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import JavaScriptKit
import OpenCombineShim
enum ScenePhaseObserver {
static var publisher = CurrentValueSubject<ScenePhase, Never>(.active)
private static var closure: JSClosure?
static func observe() {
let closure = JSClosure { _ -> JSValue in
let visibilityState = document.visibilityState.string
if visibilityState == "visible" {
publisher.send(.active)
} else if visibilityState == "hidden" {
publisher.send(.background)
}
return .undefined
}
_ = document.addEventListener!("visibilitychange", closure)
Self.closure = closure
}
}