fix for BoolToVisibility conversion: Custom types with defined implic…

…it cast to bool are unsupported by BoolToVisibility converter Alex141#53
rstroilov · Feb 3, 2018 · 0ab01e0 · 0ab01e0
1 parent f337da8
commit 0ab01e0
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Showing 2 changed files with 66 additions and 8 deletions.
diff --git a/CalcBinding/BoolToVisibilityConverter.cs b/CalcBinding/BoolToVisibilityConverter.cs
@@ -1,5 +1,8 @@
 using System;
+using System.Collections.Generic;
 using System.Globalization;
+using System.Linq;
+using System.Reflection;
 using System.Windows;
 using System.Windows.Data;
 
@@ -22,6 +25,17 @@ public BoolToVisibilityConverter(FalseToVisibility falseToVisibility)
 
         public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
         {
+            var valueType = value.GetType();
+
+            if (valueType != typeof(bool))
+            {
+                var implicitConverter = GetImplicitConversion(valueType, typeof(bool));
+                if (implicitConverter != null)
+                {
+                    value = implicitConverter.Invoke(null, new object[] { value });
+                }
+            }
+
             if ((bool)value)
                 return Visibility.Visible;
 
@@ -34,5 +48,25 @@ public object ConvertBack(object value, Type targetType, object parameter, Cultu
         }
 
         public FalseToVisibility FalseToVisibility { get; set; }
+
+        private static MethodInfo GetImplicitConversion(Type baseType, Type targetType)
+        {
+            return GetAllImplicitCasts(baseType, targetType)
+                .FirstOrDefault();
+        }
+
+        private static IEnumerable<MethodInfo> GetAllImplicitCasts(Type baseType, Type targetType)
+        {
+            var currentTypeMethods = baseType.GetMethods(BindingFlags.Public | BindingFlags.Static)
+                .Where(x => x.Name == "op_Implicit" && x.ReturnType == targetType)
+                .ToList();
+
+            while (baseType != typeof(object) && !currentTypeMethods.Any())
+            {
+                return GetAllImplicitCasts(baseType.BaseType, targetType);
+            }
+
+            return currentTypeMethods;
+        }
     }
 }
diff --git a/Tests/BoolToVisibilityConverterTests.cs b/Tests/BoolToVisibilityConverterTests.cs
@@ -1,11 +1,6 @@
 using CalcBinding;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System;
-using System.Collections.Generic;
 using System.Globalization;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Windows;
 
 namespace Tests
@@ -16,8 +11,6 @@ public class BoolToVisibilityConverterTests
         [TestMethod]
         public void ConvertBoolToVisibilityTest()
         {
-            var converter = new CalcConverter();
-
             Assert.AreEqual(Visibility.Visible, 
                 new BoolToVisibilityConverter()
                 .Convert(true, typeof(Visibility), null, CultureInfo.CurrentCulture));
@@ -45,6 +38,37 @@ public void ConvertVisibilityToBoolTest()
             Assert.AreEqual(false, 
                 new BoolToVisibilityConverter()
                 .ConvertBack(Visibility.Hidden, typeof(bool), null, CultureInfo.CurrentCulture));
-        }    
+        }
+
+        [TestMethod]
+        public void ConvertsCastableToBoolWhenValueHasImplicitConversion()
+        {
+            Assert.AreEqual(Visibility.Visible,
+                new BoolToVisibilityConverter()
+                .Convert(new CastableToBoolean(true), typeof(Visibility), null, CultureInfo.CurrentCulture));
+
+            Assert.AreEqual(Visibility.Collapsed,
+                new BoolToVisibilityConverter()
+                .Convert(new CastableToBoolean(false), typeof(Visibility), null, CultureInfo.CurrentCulture));
+
+            Assert.AreEqual(Visibility.Hidden,
+                new BoolToVisibilityConverter(FalseToVisibility.Hidden)
+                .Convert(new CastableToBoolean(false), typeof(Visibility), null, CultureInfo.CurrentCulture));
+        }
+
+        private sealed class CastableToBoolean
+        {
+            private bool value;
+
+            public CastableToBoolean(bool value = false)
+            {
+                this.value = value;
+            }
+
+            public static implicit operator bool(CastableToBoolean obj)
+            {
+                return obj.value;
+            }
+        }
     }
 }