Initial import

1 files changed, 124 insertions, 0 deletions

diff --git a/Xamarin.Forms.Core/Tweener.cs b/Xamarin.Forms.Core/Tweener.cs
new file mode 100644
index 00000000..73ed7853
--- /dev/null
+++ b/Xamarin.Forms.Core/Tweener.cs
@@ -0,0 +1,124 @@
+//
+// Tweener.cs
+//
+// Author:
+//       Jason Smith <jason.smith@xamarin.com>
+//
+// Copyright (c) 2012 Xamarin Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+using System;
+
+namespace Xamarin.Forms
+{
+	internal class Tweener
+	{
+		long _lastMilliseconds;
+
+		int _timer;
+
+		public Tweener(uint length)
+		{
+			Value = 0.0f;
+			Length = length;
+			Loop = false;
+		}
+
+		public AnimatableKey Handle { get; set; }
+
+		public uint Length { get; }
+
+		public bool Loop { get; set; }
+
+		public double Value { get; private set; }
+
+		public event EventHandler Finished;
+
+		public void Pause()
+		{
+			if (_timer != 0)
+			{
+				Ticker.Default.Remove(_timer);
+				_timer = 0;
+			}
+		}
+
+		public void Start()
+		{
+			Pause();
+
+			_lastMilliseconds = 0;
+			_timer = Ticker.Default.Insert(step =>
+			{
+				long ms = step + _lastMilliseconds;
+
+				Value = Math.Min(1.0f, ms / (double)Length);
+
+				_lastMilliseconds = ms;
+
+				if (ValueUpdated != null)
+					ValueUpdated(this, EventArgs.Empty);
+
+				if (Value >= 1.0f)
+				{
+					if (Loop)
+					{
+						_lastMilliseconds = 0;
+						Value = 0.0f;
+						return true;
+					}
+
+					if (Finished != null)
+						Finished(this, EventArgs.Empty);
+					Value = 0.0f;
+					_timer = 0;
+					return false;
+				}
+				return true;
+			});
+		}
+
+		public void Stop()
+		{
+			Pause();
+			Value = 1.0f;
+			if (Finished != null)
+				Finished(this, EventArgs.Empty);
+			Value = 0.0f;
+		}
+
+		public event EventHandler ValueUpdated;
+
+		~Tweener()
+		{
+			if (_timer != 0)
+			{
+				try
+				{
+					Ticker.Default.Remove(_timer);
+				}
+				catch (InvalidOperationException)
+				{
+				}
+			}
+			_timer = 0;
+		}
+	}
+}
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