1 files changed, 68 insertions, 0 deletions
diff --git a/Xamarin.Forms.Platform.WinRT/FormsComboBox.cs b/Xamarin.Forms.Platform.WinRT/FormsComboBox.cs
new file mode 100644
index 00000000..f693c942
--- /dev/null
+++ b/Xamarin.Forms.Platform.WinRT/FormsComboBox.cs
@@ -0,0 +1,68 @@
+using System;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Media.Animation;
+
+#if WINDOWS_UWP
+
+namespace Xamarin.Forms.Platform.UWP
+#else
+
+namespace Xamarin.Forms.Platform.WinRT
+#endif
+{
+	public class FormsComboBox : ComboBox
+	{
+		internal bool IsClosingAnimated { get; private set; }
+
+		internal bool IsFullScreen => Device.Idiom == TargetIdiom.Phone && Items != null && Items.Count > 5;
+
+		internal bool IsOpeningAnimated { get; private set; }
+
+		protected override void OnApplyTemplate()
+		{
+			base.OnApplyTemplate();
+
+			if (Device.Idiom == TargetIdiom.Phone)
+			{
+				// If we're running on the phone, we have to give the PickerRenderer hooks
+				// into the opening and closing animations so it can handle them smoothly
+				// and measure at the appropriate times
+
+				var openedState = GetTemplateChild("Opened") as VisualState;
+				if (openedState != null)
+				{
+					openedState.Storyboard.Completed += (sender, o) => OnOpenAnimationCompleted();
+					IsOpeningAnimated = true;
+				}
+
+				var closedState = GetTemplateChild("Closed") as VisualState;
+
+				// On the phone, this is a dummy animation we've added to the closed state in the VSM
+				// Since it finishes immediately, we can use its Completed event to signal that the 
+				// closing animation has started 
+				var closedSignalAnimation = closedState?.Storyboard.Children[0] as DoubleAnimation;
+
+				if (closedSignalAnimation != null)
+				{
+					closedSignalAnimation.Completed += (sender, o) => OnClosedAnimationStarted();
+					IsClosingAnimated = true;
+				}
+			}
+		}
+
+		protected virtual void OnClosedAnimationStarted()
+		{
+			ClosedAnimationStarted?.Invoke(this, EventArgs.Empty);
+		}
+
+		protected virtual void OnOpenAnimationCompleted()
+		{
+			OpenAnimationCompleted?.Invoke(this, EventArgs.Empty);
+		}
+
+		internal event EventHandler<EventArgs> ClosedAnimationStarted;
+
+		internal event EventHandler<EventArgs> OpenAnimationCompleted;
+	}
+}
+\ No newline at end of file