maui-linux/Xamarin.Forms.Platform.Android/AndroidTicker.cs

using System;
using Android.Animation;
using Android.Content;
using Android.OS;
using Xamarin.Forms.Internals;

namespace Xamarin.Forms.Platform.Android
{
	internal class AndroidTicker : Ticker, IDisposable
	{
		ValueAnimator _val;
		bool _systemEnabled;

		public AndroidTicker()
		{
			_val = new ValueAnimator();
			_val.SetIntValues(0, 100); // avoid crash
			_val.RepeatCount = ValueAnimator.Infinite;
			_val.Update += OnValOnUpdate;
			CheckPowerSaveModeStatus();
		}

		public override bool SystemEnabled => _systemEnabled;

		internal void CheckPowerSaveModeStatus()
		{
			// Android disables animations when it's in power save mode
			// So we need to keep track of whether we're in that mode and handle animations accordingly
			// We can't just check ValueAnimator.AreAnimationsEnabled() because there's no event for that, and it's
			// only supported on API >= 26

			if (!Forms.IsLollipopOrNewer)
			{
				_systemEnabled = true;
				return;
			}

			var powerManager = (PowerManager)Forms.ApplicationContext.GetSystemService(Context.PowerService);

			var powerSaveOn = powerManager.IsPowerSaveMode;

			// If power saver is active, then animations will not run
			_systemEnabled = !powerSaveOn;
			
			// Notify the ticker that this value has changed, so it can manage animations in progress
			OnSystemEnabledChanged();
		}

		public void Dispose()
		{
			if (_val != null)
			{
				_val.Update -= OnValOnUpdate;
				_val.Dispose();
			}
			_val = null;
		}

		protected override void DisableTimer()
		{
			_val?.Cancel();
		}

		protected override void EnableTimer()
		{
			_val?.Start();
		}

		void OnValOnUpdate(object sender, ValueAnimator.AnimatorUpdateEventArgs e)
		{
			SendSignals();
		}
	}
}