[Tizen] Adds the DisplayResolutionUnit (#12074)

* Apply Device size Scaling and Viewport

* Update InitializationOptions to setup DisplayResolutionUnit

* Fix DisplayResolutionUnit namespace, Fix Init method

Author: myroot

Xamarin.Forms.Platform.Tizen/DisplayResolutionUnit.cs

@@ -0,0 +1,53 @@
+using System;
+
+namespace Xamarin.Forms
+{
+	public class DisplayResolutionUnit
+	{
+		public static DisplayResolutionUnit Pixel(bool useDeviceScale = false)
+		{
+			return new DisplayResolutionUnit()
+			{
+				UseDP = false,
+				UseDeviceScale = useDeviceScale
+			};
+		}
+
+		public static DisplayResolutionUnit DP(bool useDeviceScale = false)
+		{
+			return new DisplayResolutionUnit()
+			{
+				UseDP = true,
+				UseDeviceScale = useDeviceScale
+			};
+		}
+
+		public static DisplayResolutionUnit VP(double width)
+		{
+			if (width <= 0)
+				throw new ArgumentException("width must be bigger than 0", "width");
+
+			return new DisplayResolutionUnit()
+			{
+				UseVP = true,
+				UseDeviceScale = false,
+				ViewportWidth = width
+			};
+		}
+
+		internal static DisplayResolutionUnit FromInit(bool useDP)
+		{
+			return useDP ? DP() : Pixel();
+		}
+
+		DisplayResolutionUnit() { }
+
+		public bool UseDP { get; private set; }
+
+		public bool UseDeviceScale { get; private set; }
+
+		public bool UseVP { get; private set; }
+
+		public double ViewportWidth { get; private set; } = -1;
+	}
+}

Xamarin.Forms.Platform.Tizen/Forms.cs

@@ -41,6 +41,8 @@ public class InitializationOptions
 		public PlatformType PlatformType { get; set; }
 		public bool UseMessagingCenter { get; set; } = true;
 
+		public DisplayResolutionUnit DisplayResolutionUnit { get; set; }
+
 		public struct EffectScope
 		{
 			public string Name;
@@ -163,9 +165,31 @@ public TizenDeviceInfo()
 				TSystemInfo.TryGetValue("http://tizen.org/feature/screen.height", out height);
 
 				scalingFactor = 1.0;  // scaling is disabled, we're using pixels as Xamarin's geometry units
-				if (s_useDeviceIndependentPixel)
+				if (DisplayResolutionUnit.UseVP && DisplayResolutionUnit.ViewportWidth > 0)
 				{
-					scalingFactor = s_dpi.Value / 160.0;
+					scalingFactor = width / DisplayResolutionUnit.ViewportWidth;
+				}
+				else
+				{
+					if (DisplayResolutionUnit.UseDP)
+					{
+						scalingFactor = s_dpi.Value / 160.0;
+					}
+
+					if (DisplayResolutionUnit.UseDeviceScale)
+					{
+						var physicalScale = s_dpi.Value / 160.0;
+
+						var portraitSize = (Math.Min(width, height)) / physicalScale;
+						if (portraitSize > 2000)
+						{
+							scalingFactor *= 4;
+						}
+						else if (portraitSize > 1000)
+						{
+							scalingFactor *= 2.5;
+						}
+					}
 				}
 
 				pixelScreenSize = new Size(width, height);
@@ -174,8 +198,6 @@ public TizenDeviceInfo()
 			}
 		}
 
-		static bool s_useDeviceIndependentPixel = false;
-
 		static StaticRegistrarStrategy s_staticRegistrarStrategy = StaticRegistrarStrategy.None;
 
 		static PlatformType s_platformType = PlatformType.Defalut;
@@ -222,6 +244,8 @@ public static bool IsInitialized
 
 		public static bool UseMessagingCenter => s_useMessagingCenter;
 
+		public static DisplayResolutionUnit DisplayResolutionUnit { get; private set; }
+
 		internal static TizenTitleBarVisibility TitleBarVisibility
 		{
 			get;
@@ -348,13 +372,24 @@ public static void Init(CoreApplication application)
 
 		public static void Init(CoreApplication application, bool useDeviceIndependentPixel)
 		{
-			s_useDeviceIndependentPixel = useDeviceIndependentPixel;
+			DisplayResolutionUnit = DisplayResolutionUnit.FromInit(useDeviceIndependentPixel);
+			SetupInit(application);
+		}
+
+		public static void Init(CoreApplication application, DisplayResolutionUnit unit)
+		{
+			DisplayResolutionUnit = unit ?? DisplayResolutionUnit.Pixel();
 			SetupInit(application);
 		}
 
 		public static void Init(InitializationOptions options)
 		{
-			s_useDeviceIndependentPixel = options?.UseDeviceIndependentPixel ?? false;
+			if (options == null)
+			{
+				throw new ArgumentException("Must be set options", nameof(options));
+			}
+
+			DisplayResolutionUnit = options.DisplayResolutionUnit ?? DisplayResolutionUnit.FromInit(options.UseDeviceIndependentPixel);
 			SetupInit(options.Context, options);
 		}