Merge pull request #11020 from AvaloniaUI/fixes/direction-degrees

DropShadowEffect Direction is in degrees, not radians

src/Avalonia.Base/Media/Effects/DropShadowEffect.cs

@@ -18,7 +18,7 @@ public abstract class DropShadowEffectBase : Effect
     }
 
     public static readonly StyledProperty<Color> ColorProperty = AvaloniaProperty.Register<DropShadowEffectBase, Color>(
-        nameof(Color));
+        nameof(Color), Colors.Black);
 
     public Color Color
     {
@@ -97,8 +97,8 @@ public class DropShadowDirectionEffect : DropShadowEffectBase, IDirectionDropSha
         set => SetValue(DirectionProperty, value);
     }
     
-    public double OffsetX => Math.Cos(Direction) * ShadowDepth;
-    public double OffsetY => Math.Sin(Direction) * ShadowDepth;
+    public double OffsetX => Math.Cos(Direction * Math.PI / 180) * ShadowDepth;
+    public double OffsetY => Math.Sin(Direction * Math.PI / 180) * ShadowDepth;
     
     public IImmutableEffect ToImmutable() => new ImmutableDropShadowDirectionEffect(OffsetX, OffsetY, BlurRadius, Color, Opacity);
 }

src/Avalonia.Base/Media/Effects/IDropShadowEffect.cs

@@ -67,8 +67,8 @@ public class ImmutableDropShadowDirectionEffect : IDirectionDropShadowEffect, II
         Opacity = opacity;
     }
     
-    public double OffsetX => Math.Cos(Direction) * ShadowDepth;
-    public double OffsetY => Math.Sin(Direction) * ShadowDepth;
+    public double OffsetX => Math.Cos(Direction * Math.PI / 180) * ShadowDepth;
+    public double OffsetY => Math.Sin(Direction * Math.PI / 180) * ShadowDepth;
     public double Direction { get; }
     public double ShadowDepth { get; }
     public double BlurRadius { get; }