Add TextColor Property to Picker, TimePicker, DatePicker (#84)

* Add TextColor property to TimePicker
Add TextColor page to TimePicker gallery
Add TimePicker color toggling to color toggle test page
Split color toggle tests up among tabs

* Implement TimePicker.TextColor in iOS

* Implement TimePicker.TextColor for WinRT tablet

* Add IsEnabled=false tests to DefaultColorToggleTest Button and TimePicker
Consolidate ColorStates array
Fix IsEnabled changing color bug on iOS

* Implement TimePicker.TextColor for WP8

* Add TextColor property to DatePicker
Add DatePicker section to DefaultColorToggleTest
Impement DatePicker.TextColor for WP8

* Implement DatePicker.TextColor for WinRT/UWP/Windows Phone 8.1

* Implement DatePicker.TextColor for iOS

* Add TextColor to DatePicker Gallery Page

* Implement DatePicker.TextColor for Android

* Add Picker Gallery page for TextColor
Implement Picker.TextColor on Android
Consolidate TextColor management for Button, Picker, DatePicker, TimePicker
Implement

* Add untracked TextColorSwitcher
Implement Picker.TextColor in iOS

* Implement Picker.TextColor in WinRT/UWP/Windows Phone 8.1
Remove Pioker Loaded handlers in Dispose

* Implement Picker.TextColor in WP8

* Removed unused field
Update ignored warnings

* Update docs

* Use nameof() for BindableProperties

* Cleanup

* Fix custom renderer crashes for classes using TextColorSwitcher

* Correct property name references

* Fix typo and 'if' formatting

* Add missing else

2 files changed, 20 insertions, 24 deletions

diff --git a/Xamarin.Forms.Platform.Android/AppCompat/ButtonRenderer.cs b/Xamarin.Forms.Platform.Android/AppCompat/ButtonRenderer.cs
index 3260dbf1..8f4ef35e 100644
--- a/Xamarin.Forms.Platform.Android/AppCompat/ButtonRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/AppCompat/ButtonRenderer.cs
@@ -14,10 +14,7 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 {
 	public class ButtonRenderer : ViewRenderer<Button, AppCompatButton>, global::Android.Views.View.IOnAttachStateChangeListener
 	{
-		static readonly int[][] States = { new[] { GlobalResource.Attribute.StateEnabled }, new[] { -GlobalResource.Attribute.StateEnabled } };
-
-		ColorStateList _buttonDefaulTextColors;
-		Color _currentTextColor;
+		TextColorSwitcher _textColorSwitcher;
 		float _defaultFontSize;
 		Typeface _defaultTypeface;
 		bool _isDisposed;
@@ -79,7 +76,7 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 
 					button.SetOnClickListener(ButtonClickListener.Instance.Value);
 					button.Tag = this;
-					_buttonDefaulTextColors = button.TextColors;
+					_textColorSwitcher = new TextColorSwitcher(button.TextColors);  
 					SetNativeControl(button);
 
 					button.AddOnAttachStateChangeListener(this);
@@ -128,14 +125,16 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 							{
 								Resources.Theme theme = context.Theme;
 								if (theme != null && theme.ResolveAttribute(id, value, true))
-									Control.SupportBackgroundTintList = ContextCompat.GetColorStateList(context, value.Data);
+#pragma warning disable 618
+									Control.SupportBackgroundTintList = Resources.GetColorStateList(value.Data);
+#pragma warning restore 618
 								else
-									Control.SupportBackgroundTintList = new ColorStateList(States, new[] { (int)0xffd7d6d6, 0x7fd7d6d6 });
+									Control.SupportBackgroundTintList = new ColorStateList(ColorExtensions.States, new[] { (int)0xffd7d6d6, 0x7fd7d6d6 });
 							}
 							catch (Exception ex)
 							{
 								Log.Warning("Xamarin.Forms.Platform.Android.ButtonRenderer", "Could not retrieve button background resource: {0}", ex);
-								Control.SupportBackgroundTintList = new ColorStateList(States, new[] { (int)0xffd7d6d6, 0x7fd7d6d6 });
+								Control.SupportBackgroundTintList = new ColorStateList(ColorExtensions.States, new[] { (int)0xffd7d6d6, 0x7fd7d6d6 });
 							}
 						}
 					}
@@ -145,7 +144,7 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 			{
 				int intColor = backgroundColor.ToAndroid().ToArgb();
 				int disableColor = backgroundColor.MultiplyAlpha(0.5).ToAndroid().ToArgb();
-				Control.SupportBackgroundTintList = new ColorStateList(States, new[] { intColor, disableColor });
+				Control.SupportBackgroundTintList = new ColorStateList(ColorExtensions.States, new[] { intColor, disableColor });
 			}
 		}
 
@@ -245,21 +244,7 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 
 		void UpdateTextColor()
 		{
-			Color color = Element.TextColor;
-			if (color == _currentTextColor)
-				return;
-
-			_currentTextColor = color;
-
-			if (color.IsDefault)
-				NativeButton.SetTextColor(_buttonDefaulTextColors);
-			else
-			{
-				// Set the new enabled state color, preserving the default disabled state color
-				int defaultDisabledColor = _buttonDefaulTextColors.GetColorForState(States[1], color.ToAndroid());
-
-				NativeButton.SetTextColor(new ColorStateList(States, new[] { color.ToAndroid().ToArgb(), defaultDisabledColor }));
-			}
+			_textColorSwitcher?.UpdateTextColor(Control, Element.TextColor);
 		}
 
 		class ButtonClickListener : Object, IOnClickListener
diff --git a/Xamarin.Forms.Platform.Android/AppCompat/PickerRenderer.cs b/Xamarin.Forms.Platform.Android/AppCompat/PickerRenderer.cs
index dd7fb85c..492b553b 100644
--- a/Xamarin.Forms.Platform.Android/AppCompat/PickerRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/AppCompat/PickerRenderer.cs
@@ -2,6 +2,7 @@ using System;
 using System.ComponentModel;
 using System.Linq;
 using Android.App;
+using Android.Content.Res;
 using Android.Text;
 using Android.Widget;
 using Object = Java.Lang.Object;
@@ -12,6 +13,7 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 	{
 		AlertDialog _dialog;
 		bool _disposed;
+		TextColorSwitcher _textColorSwitcher;
 
 		public PickerRenderer()
 		{
@@ -51,9 +53,11 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 					textField.Tag = this;
 					textField.InputType = InputTypes.Null;
 					textField.SetOnClickListener(PickerListener.Instance);
+					_textColorSwitcher = new TextColorSwitcher(textField.TextColors);
 					SetNativeControl(textField);
 				}
 				UpdatePicker();
+				UpdateTextColor();
 			}
 
 			base.OnElementChanged(e);
@@ -67,6 +71,8 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 				UpdatePicker();
 			if (e.PropertyName == Picker.SelectedIndexProperty.PropertyName)
 				UpdatePicker();
+			if (e.PropertyName == Picker.TextColorProperty.PropertyName)
+				UpdateTextColor();
 		}
 
 		internal override void OnFocusChangeRequested(object sender, VisualElement.FocusRequestArgs e)
@@ -123,6 +129,11 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 				Control.Text = Element.Items[Element.SelectedIndex];
 		}
 
+		void UpdateTextColor()
+		{
+			_textColorSwitcher?.UpdateTextColor(Control, Element.TextColor);
+		}
+
 		class PickerListener : Object, IOnClickListener
 		{
 			#region Statics