From 33e1a65f5985da892d5934cca2f5982c46d0752c Mon Sep 17 00:00:00 2001
From: "Frank A. Krueger" <fak@praeclarum.org>
Date: Sat, 9 Dec 2017 22:19:16 -0800
Subject: [PATCH] Implement the platform ticker

---
 Ooui.Forms/Forms.cs                   | 36 +++++++++++++++++++++------
 Ooui.Forms/Renderers/LabelRenderer.cs |  3 +++
 Ooui/UI.cs                            |  4 ++-
 3 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/Ooui.Forms/Forms.cs b/Ooui.Forms/Forms.cs
index c5a39f7..991c264 100644
--- a/Ooui.Forms/Forms.cs
+++ b/Ooui.Forms/Forms.cs
@@ -30,9 +30,9 @@ namespace Xamarin.Forms
 
             Registrar.RegisterAll (new[] {
                 typeof(ExportRendererAttribute),
-				//typeof(ExportCellAttribute),
-				//typeof(ExportImageSourceHandlerAttribute),
-			});
+                //typeof(ExportCellAttribute),
+                //typeof(ExportImageSourceHandlerAttribute),
+            });
         }
 
         public static event EventHandler<ViewInitializedEventArgs> ViewInitialized;
@@ -62,11 +62,6 @@ namespace Xamarin.Forms
                 Task.Run (action);
             }
 
-            public Ticker CreateTicker ()
-            {
-                throw new NotImplementedException ();
-            }
-
             public Assembly[] GetAssemblies ()
             {
                 return AppDomain.CurrentDomain.GetAssemblies ();
@@ -119,6 +114,31 @@ namespace Xamarin.Forms
                     }
                 }), null, (int)interval.TotalMilliseconds, (int)interval.TotalMilliseconds);
             }
+
+            public Ticker CreateTicker ()
+            {
+                return new OouiTicker ();
+            }
+
+            class OouiTicker : Ticker
+            {
+                Timer timer;
+                protected override void DisableTimer ()
+                {
+                    var t = timer;
+                    timer = null;
+                    t?.Dispose ();
+                }
+                protected override void EnableTimer ()
+                {
+                    if (timer != null)
+                        return;
+                    var interval = TimeSpan.FromSeconds (1.0 / Ooui.UI.Session.MaxFps);
+                    timer = new Timer ((_ => {
+                        this.SendSignals ();
+                    }), null, (int)interval.TotalMilliseconds, (int)interval.TotalMilliseconds);
+                }
+            }
         }
 
         public class ViewInitializedEventArgs
diff --git a/Ooui.Forms/Renderers/LabelRenderer.cs b/Ooui.Forms/Renderers/LabelRenderer.cs
index df396a3..9be0486 100644
--- a/Ooui.Forms/Renderers/LabelRenderer.cs
+++ b/Ooui.Forms/Renderers/LabelRenderer.cs
@@ -74,6 +74,9 @@ namespace Ooui.Forms.Renderers
         {
             base.OnElementPropertyChanged (sender, e);
 
+            if (Control == null)
+                return;
+
             if (e.PropertyName == Xamarin.Forms.Label.HorizontalTextAlignmentProperty.PropertyName)
                 UpdateAlignment ();
             else if (e.PropertyName == Xamarin.Forms.Label.VerticalTextAlignmentProperty.PropertyName)
diff --git a/Ooui/UI.cs b/Ooui/UI.cs
index 768d992..a422abf 100644
--- a/Ooui/UI.cs
+++ b/Ooui/UI.cs
@@ -522,9 +522,11 @@ namespace Ooui
             readonly HashSet<string> createdIds;
             readonly List<Message> queuedMessages = new List<Message> ();
 
+            public const int MaxFps = 30;
+
             readonly System.Timers.Timer sendThrottle;
             DateTime lastTransmitTime = DateTime.MinValue;
-            readonly TimeSpan throttleInterval = TimeSpan.FromSeconds (1.0 / 30); // 30 FPS max
+            readonly TimeSpan throttleInterval = TimeSpan.FromSeconds (1.0 / MaxFps);
             readonly double initialWidth;
             readonly double initialHeight;