Readable coloring for calendar events.

Wino.Calendar/Styles/WinoCalendarResources.xaml

@@ -5,6 +5,7 @@
     xmlns:controls="using:Wino.Calendar.Controls"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:data="using:Wino.Calendar.ViewModels.Data"
+    xmlns:helpers="using:Wino.Helpers"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:models="using:Wino.Core.Domain.Models.Calendar"
     xmlns:muxc="using:Microsoft.UI.Xaml.Controls"
@@ -12,9 +13,12 @@
 
     <!--  Default Calendar Item View Model Template  -->
     <DataTemplate x:Key="CalendarItemViewModelItemTemplate" x:DataType="data:CalendarItemViewModel">
-        <Grid Background="Red" CornerRadius="4">
+        <Grid Background="{x:Bind helpers:XamlHelpers.GetSolidColorBrushFromHex(AssignedCalendar.BackgroundColorHex), Mode=OneWay}" CornerRadius="4">
             <TextBlock
+                Margin="2,0"
                 HorizontalAlignment="Center"
+                VerticalAlignment="Center"
+                Foreground="{x:Bind helpers:XamlHelpers.GetReadableTextColor(AssignedCalendar.BackgroundColorHex), Mode=OneWay}"
                 Text="{x:Bind CalendarItem.Title}"
                 TextWrapping="Wrap" />
         </Grid>

Wino.Core.UWP/Helpers/XamlHelpers.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Globalization;
 using System.Linq;
 using Microsoft.Toolkit.Uwp.Helpers;
 using Microsoft.UI.Xaml.Controls;
@@ -42,6 +43,37 @@ namespace Wino.Helpers
             };
         }
 
+        public static SolidColorBrush GetReadableTextColor(string backgroundColor)
+        {
+            if (!backgroundColor.StartsWith("#")) throw new ArgumentException("Hex color must start with #.");
+
+            backgroundColor = backgroundColor.TrimStart('#');
+
+            if (backgroundColor.Length == 6)
+            {
+                var r = int.Parse(backgroundColor.Substring(0, 2), NumberStyles.HexNumber);
+                var g = int.Parse(backgroundColor.Substring(2, 2), NumberStyles.HexNumber);
+                var b = int.Parse(backgroundColor.Substring(4, 2), NumberStyles.HexNumber);
+
+                // Calculate relative luminance
+                double luminance = (0.2126 * GetLinearValue(r)) +
+                                   (0.7152 * GetLinearValue(g)) +
+                                   (0.0722 * GetLinearValue(b));
+
+                return luminance > 0.5 ? new SolidColorBrush(Colors.Black) : new SolidColorBrush(Colors.White);
+            }
+            else
+            {
+                throw new ArgumentException("Hex color must be 6 characters long (e.g., #RRGGBB).");
+            }
+        }
+
+        private static double GetLinearValue(int colorComponent)
+        {
+            double sRGB = colorComponent / 255.0;
+            return sRGB <= 0.03928 ? sRGB / 12.92 : Math.Pow((sRGB + 0.055) / 1.055, 2.4);
+        }
+
         public static Microsoft.UI.Xaml.Controls.NavigationViewDisplayMode NavigationViewDisplayModeConverter(SplitViewDisplayMode splitViewDisplayMode)
         {
             return splitViewDisplayMode switch