Merge pull request #3942 from markl65536/FixTypeUtilities

Fix type utilities

src/Avalonia.Base/Utilities/TypeUtilities.cs

@@ -115,45 +115,46 @@ namespace Avalonia.Utilities
                 return true;
             }
 
+            var toUnderl = Nullable.GetUnderlyingType(to) ?? to;
             var from = value.GetType();
 
-            if (to.IsAssignableFrom(from))
+            if (toUnderl.IsAssignableFrom(from))
             {
                 result = value;
                 return true;
             }
 
-            if (to == typeof(string))
+            if (toUnderl == typeof(string))
             {
-                result = Convert.ToString(value);
+                result = Convert.ToString(value, culture);
                 return true;
             }
 
-            if (to.IsEnum && from == typeof(string))
+            if (toUnderl.IsEnum && from == typeof(string))
             {
-                if (Enum.IsDefined(to, (string)value))
+                if (Enum.IsDefined(toUnderl, (string)value))
                 {
-                    result = Enum.Parse(to, (string)value);
+                    result = Enum.Parse(toUnderl, (string)value);
                     return true;
                 }
             }
 
-            if (!from.IsEnum && to.IsEnum)
+            if (!from.IsEnum && toUnderl.IsEnum)
             {
                 result = null;
 
-                if (TryConvert(Enum.GetUnderlyingType(to), value, culture, out object enumValue))
+                if (TryConvert(Enum.GetUnderlyingType(toUnderl), value, culture, out object enumValue))
                 {
-                    result = Enum.ToObject(to, enumValue);
+                    result = Enum.ToObject(toUnderl, enumValue);
                     return true;
                 }
             }
 
-            if (from.IsEnum && IsNumeric(to))
+            if (from.IsEnum && IsNumeric(toUnderl))
             {
                 try
                 {
-                    result = Convert.ChangeType((int)value, to, culture);
+                    result = Convert.ChangeType((int)value, toUnderl, culture);
                     return true;
                 }
                 catch
@@ -164,7 +165,7 @@ namespace Avalonia.Utilities
             }
 
             var convertableFrom = Array.IndexOf(InbuiltTypes, from);
-            var convertableTo = Array.IndexOf(InbuiltTypes, to);
+            var convertableTo = Array.IndexOf(InbuiltTypes, toUnderl);
 
             if (convertableFrom != -1 && convertableTo != -1)
             {
@@ -172,7 +173,7 @@ namespace Avalonia.Utilities
                 {
                     try
                     {
-                        result = Convert.ChangeType(value, to, culture);
+                        result = Convert.ChangeType(value, toUnderl, culture);
                         return true;
                     }
                     catch
@@ -183,15 +184,23 @@ namespace Avalonia.Utilities
                 }
             }
 
-            var typeConverter = TypeDescriptor.GetConverter(to);
+            var toTypeConverter = TypeDescriptor.GetConverter(toUnderl);
+
+            if (toTypeConverter.CanConvertFrom(from) == true)
+            {
+                result = toTypeConverter.ConvertFrom(null, culture, value);
+                return true;
+            }
+
+            var fromTypeConverter = TypeDescriptor.GetConverter(from);
 
-            if (typeConverter.CanConvertFrom(from) == true)
+            if (fromTypeConverter.CanConvertTo(toUnderl) == true)
             {
-                result = typeConverter.ConvertFrom(null, culture, value);
+                result = fromTypeConverter.ConvertTo(null, culture, value, toUnderl);
                 return true;
             }
 
-            var cast = FindTypeConversionOperatorMethod(from, to, OperatorType.Implicit | OperatorType.Explicit);
+            var cast = FindTypeConversionOperatorMethod(from, toUnderl, OperatorType.Implicit | OperatorType.Explicit);
 
             if (cast != null)
             {

tests/Avalonia.Base.UnitTests/Data/DefaultValueConverterTests.cs

@@ -6,6 +6,7 @@ using System.Windows.Input;
 using System;
 using Avalonia.Data.Converters;
 using Avalonia.Layout;
+using System.ComponentModel;
 
 namespace Avalonia.Base.UnitTests.Data.Converters
 {
@@ -35,6 +36,54 @@ namespace Avalonia.Base.UnitTests.Data.Converters
             Assert.Equal(5.0, result);
         }
 
+        [Fact]
+        public void Do_Not_Throw_On_InvalidInput_For_NullableInt()
+        {
+            var result = DefaultValueConverter.Instance.Convert(
+                "<not-a-number>",
+                typeof(int?),
+                null,
+                CultureInfo.InvariantCulture);
+
+            Assert.IsType(typeof(BindingNotification), result);
+        }
+
+        [Fact]
+        public void Can_Convert_Decimal_To_NullableDouble()
+        {
+            var result = DefaultValueConverter.Instance.Convert(
+                5m,
+                typeof(double?),
+                null,
+                CultureInfo.InvariantCulture);
+
+            Assert.Equal(5.0, result);
+        }
+
+        [Fact]
+        public void Can_Convert_CustomType_To_Int()
+        {
+            var result = DefaultValueConverter.Instance.Convert(
+                new CustomType(123),
+                typeof(int),
+                null,
+                CultureInfo.InvariantCulture);
+
+            Assert.Equal(123, result);
+        }
+
+        [Fact]
+        public void Can_Convert_Int_To_CustomType()
+        {
+            var result = DefaultValueConverter.Instance.Convert(
+                123,
+                typeof(CustomType),
+                null,
+                CultureInfo.InvariantCulture);
+
+            Assert.Equal(new CustomType(123), result);
+        }
+
         [Fact]
         public void Can_Convert_String_To_Enum()
         {
@@ -187,5 +236,44 @@ namespace Avalonia.Base.UnitTests.Data.Converters
                 return v.Value;
             }
         }
+
+        [TypeConverter(typeof(CustomTypeConverter))]
+        private class CustomType {
+
+            public int Value { get; }
+
+            public CustomType(int value)
+            {
+                Value = value;
+            }
+
+            public override bool Equals(object obj)
+            {
+                return obj is CustomType other && this.Value == other.Value;
+            }
+        }
+
+        private class CustomTypeConverter : TypeConverter
+        {
+            public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
+            {
+                return destinationType == typeof(int);
+            }
+
+            public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
+            {
+                return sourceType == typeof(int);
+            }
+
+            public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
+            {
+                return ((CustomType)value).Value;
+            }
+
+            public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
+            {
+                return new CustomType((int)value);
+            }
+        }
     }
 }