add converters for DateOnly and TimeOnly

Author: Edward Miller

src/Controls/src/Core/DateOnlyConverter.cs

@@ -0,0 +1,55 @@
+#if NET6_0_OR_GREATER
+using System;
+using System.ComponentModel;
+using System.Globalization;
+
+namespace Microsoft.Maui.Controls
+{
+    internal class DateOnlyConverter : TypeConverter, IExtendedTypeConverter
+    {
+        public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
+            => sourceType == typeof(string) || sourceType == typeof(DateTime);
+
+        public override bool CanConvertTo(ITypeDescriptorContext? context, Type? destinationType)
+            => destinationType == typeof(string) || destinationType == typeof(DateTime);
+
+        object IExtendedTypeConverter.ConvertFromInvariantString(string value, IServiceProvider serviceProvider)
+        {
+            if (DateTime.TryParse(value, CultureInfo.InvariantCulture, DateTimeStyles.None, out var result))
+            {
+                return DateOnly.FromDateTime(result);
+            }
+            throw new NotSupportedException($"Cannot convert \"{value}\" into {typeof(DateOnly)}");
+        }
+
+        public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object? value)
+        {
+            if (value is DateTime dateTime)
+            {
+                return DateOnly.FromDateTime(dateTime);
+            }
+            if (value is string stringValue && DateTime.TryParse(stringValue, CultureInfo.InvariantCulture, DateTimeStyles.None, out var result))
+            {
+                return DateOnly.FromDateTime(result);
+            }
+            throw new NotSupportedException($"Cannot convert \"{value}\" into {typeof(DateOnly)}");
+        }
+
+        public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
+        {
+            if (value is DateOnly dateOnly)
+            {
+                if (destinationType == typeof(string))
+                {
+                    return dateOnly.ToString(culture);
+                }
+                if (destinationType == typeof(DateTime))
+                {
+                    return dateOnly.ToDateTime(TimeOnly.MinValue);
+                }
+            }
+            throw new NotSupportedException($"Cannot convert \"{value}\" into {destinationType}");
+        }
+    }
+}
+#endif

src/Controls/src/Core/DatePicker/DatePicker.cs

@@ -52,6 +52,9 @@ public DatePicker()
 		}
 
 		/// <include file="../../docs/Microsoft.Maui.Controls/DatePicker.xml" path="//Member[@MemberName='Date']/Docs/*" />
+#if NET6_0_OR_GREATER
+		[System.ComponentModel.TypeConverter(typeof(DateOnlyConverter))]
+#endif
 		public DateTime Date
 		{
 			get { return (DateTime)GetValue(DateProperty); }

src/Controls/src/Core/TimeOnlyConverter.cs

@@ -0,0 +1,55 @@
+#if NET6_0_OR_GREATER
+using System;
+using System.ComponentModel;
+using System.Globalization;
+
+namespace Microsoft.Maui.Controls
+{
+    internal class TimeOnlyToTimeSpanConverter : TypeConverter, IExtendedTypeConverter
+    {
+        public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
+            => sourceType == typeof(string) || sourceType == typeof(TimeOnly);
+
+        public override bool CanConvertTo(ITypeDescriptorContext? context, Type? destinationType)
+            => destinationType == typeof(string) || destinationType == typeof(TimeSpan);
+
+        object IExtendedTypeConverter.ConvertFromInvariantString(string value, IServiceProvider serviceProvider)
+        {
+            if (TimeOnly.TryParse(value, out var result))
+            {
+                return result.ToTimeSpan();
+            }
+            throw new NotSupportedException($"Cannot convert \"{value}\" into {typeof(TimeSpan)}");
+        }
+
+        public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object? value)
+        {
+            if (value is TimeOnly timeOnly)
+            {
+                return timeOnly.ToTimeSpan();
+            }
+            if (value is string stringValue && TimeOnly.TryParse(stringValue, out var result))
+            {
+                return result.ToTimeSpan();
+            }
+            throw new NotSupportedException($"Cannot convert \"{value}\" into {typeof(TimeSpan)}");
+        }
+
+        public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
+        {
+            if (value is TimeSpan timeSpan)
+            {
+                if (destinationType == typeof(string))
+                {
+                    return timeSpan.ToString();
+                }
+                if (destinationType == typeof(TimeOnly))
+                {
+                    return TimeOnly.FromTimeSpan(timeSpan);
+                }
+            }
+            throw new NotSupportedException($"Cannot convert \"{value}\" into {destinationType}");
+        }
+    }
+}
+#endif

src/Controls/src/Core/TimePicker/TimePicker.cs

@@ -67,6 +67,9 @@ public double CharacterSpacing
 		}
 
 		/// <include file="../../docs/Microsoft.Maui.Controls/TimePicker.xml" path="//Member[@MemberName='Time']/Docs/*" />
+#if NET6_0_OR_GREATER
+		[System.ComponentModel.TypeConverter(typeof(TimeOnlyConverter))]
+#endif
 		public TimeSpan Time
 		{
 			get { return (TimeSpan)GetValue(TimeProperty); }