From 520ff4a227d599a2ef68ed13478cff1bd3308bb3 Mon Sep 17 00:00:00 2001
From: "E.Z. Hart" <hartez@users.noreply.github.com>
Date: Thu, 26 Jan 2017 11:51:28 -0700
Subject: Use a prototype TextBlock to resolve theme resources on Windows
 (#703)

* Use a prototype TextBlock to resolve theme resources on Windows

* Move textblock declaration to beginning of class

* Don't retain prototype TextBlock in memory
---
 .../WindowsResourcesProvider.cs                    | 67 +++++++++-------------
 1 file changed, 27 insertions(+), 40 deletions(-)

(limited to 'Xamarin.Forms.Platform.WinRT.Tablet')

diff --git a/Xamarin.Forms.Platform.WinRT.Tablet/WindowsResourcesProvider.cs b/Xamarin.Forms.Platform.WinRT.Tablet/WindowsResourcesProvider.cs
index 64041c00..c4485679 100644
--- a/Xamarin.Forms.Platform.WinRT.Tablet/WindowsResourcesProvider.cs
+++ b/Xamarin.Forms.Platform.WinRT.Tablet/WindowsResourcesProvider.cs
@@ -1,7 +1,7 @@
-using System;
-using Windows.UI.Text;
+using Windows.UI.Text;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
+using WStyle = Windows.UI.Xaml.Style;
 
 #if WINDOWS_UWP
 
@@ -15,60 +15,47 @@ namespace Xamarin.Forms.Platform.WinRT
 	{
 		public IResourceDictionary GetSystemResources()
 		{
-			Windows.UI.Xaml.ResourceDictionary windowsResources = Windows.UI.Xaml.Application.Current.Resources;
+			var prototype = new TextBlock();
+
+			return new ResourceDictionary
+			{
+				[Device.Styles.TitleStyleKey] = GetStyle("HeaderTextBlockStyle", prototype),
+				[Device.Styles.SubtitleStyleKey] = GetStyle("SubheaderTextBlockStyle", prototype),
+				[Device.Styles.BodyStyleKey] = GetStyle("BodyTextBlockStyle", prototype),
+				[Device.Styles.CaptionStyleKey] = GetStyle("CaptionTextBlockStyle", prototype),
+				[Device.Styles.ListItemDetailTextStyleKey] = GetStyle("BodyTextBlockStyle", prototype),
 
-			var resources = new ResourceDictionary();
-			resources[Device.Styles.TitleStyleKey] = GetStyle("HeaderTextBlockStyle");
-			resources[Device.Styles.SubtitleStyleKey] = GetStyle("SubheaderTextBlockStyle");
-			resources[Device.Styles.BodyStyleKey] = GetStyle("BodyTextBlockStyle");
-			resources[Device.Styles.CaptionStyleKey] = GetStyle("CaptionTextBlockStyle");
 #if WINDOWS_UWP
-			resources[Device.Styles.ListItemTextStyleKey] = GetStyle("BaseTextBlockStyle");
+				[Device.Styles.ListItemTextStyleKey] = GetStyle("BaseTextBlockStyle", prototype),
 #else
-			resources[Device.Styles.ListItemTextStyleKey] = GetStyle("TitleTextBlockStyle");
+				[Device.Styles.ListItemTextStyleKey] = GetStyle("TitleTextBlockStyle", prototype),
 #endif
-			resources[Device.Styles.ListItemDetailTextStyleKey] = GetStyle("BodyTextBlockStyle");
-			return resources;
+			};
 		}
 
-		Style GetStyle(object nativeKey)
+		Style GetStyle(object nativeKey, TextBlock prototype)
 		{
-			var style = (Windows.UI.Xaml.Style)Windows.UI.Xaml.Application.Current.Resources[nativeKey];
+			var style = (WStyle)Windows.UI.Xaml.Application.Current.Resources[nativeKey];
 
-			var formsStyle = new Style(typeof(Label));
-			foreach (SetterBase b in style.Setters)
-			{
-				var setter = b as Windows.UI.Xaml.Setter;
-				if (setter == null)
-					continue;
+			prototype.Style = style;
 
-				// TODO: Need to implement a stealth pass-through for things we don't support
+			var formsStyle = new Style(typeof(Label));
 
-				try
-				{
-					if (setter.Property == TextBlock.FontSizeProperty)
-						formsStyle.Setters.Add(Label.FontSizeProperty, setter.Value);
-					else if (setter.Property == TextBlock.FontFamilyProperty)
-						formsStyle.Setters.Add(Label.FontFamilyProperty, setter.Value);
-					else if (setter.Property == TextBlock.FontWeightProperty)
-						formsStyle.Setters.Add(Label.FontAttributesProperty, ToAttributes(Convert.ToUInt16(setter.Value)));
-					else if (setter.Property == TextBlock.TextWrappingProperty)
-						formsStyle.Setters.Add(Label.LineBreakModeProperty, ToLineBreakMode((TextWrapping)setter.Value));
-				}
-				catch (NotImplementedException)
-				{
-					// see https://bugzilla.xamarin.com/show_bug.cgi?id=33135
-					// WinRT implementation of Windows.UI.Xaml.Setter.get_Value is not implemented.
-				}
-			}
+			formsStyle.Setters.Add(Label.FontSizeProperty, prototype.FontSize);
+			formsStyle.Setters.Add(Label.FontFamilyProperty, prototype.FontFamily.Source);
+			formsStyle.Setters.Add(Label.FontAttributesProperty, ToAttributes(prototype.FontWeight));
+			formsStyle.Setters.Add(Label.LineBreakModeProperty, ToLineBreakMode(prototype.TextWrapping));
 
 			return formsStyle;
 		}
 
-		static FontAttributes ToAttributes(ushort uweight)
+		static FontAttributes ToAttributes(FontWeight fontWeight)
 		{
-			if (uweight == FontWeights.Bold.Weight || uweight == FontWeights.SemiBold.Weight || uweight == FontWeights.ExtraBold.Weight)
+			if (fontWeight.Weight == FontWeights.Bold.Weight || fontWeight.Weight == FontWeights.SemiBold.Weight 
+				|| fontWeight.Weight == FontWeights.ExtraBold.Weight)
+			{
 				return FontAttributes.Bold;
+			}
 
 			return FontAttributes.None;
 		}
-- 
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