Get basic alpha support working

2 files changed, 30 insertions, 7 deletions

diff --git a/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs b/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs
index 502bb06..1527581 100644
--- a/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs
+++ b/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs
@@ -28,7 +28,7 @@ namespace Xamarin.PropertyEditing.Mac
 
 		public override void MouseDown (NSEvent theEvent) {
 			if (Popover != null)
-				Popover.Show (new CGRect (20, this.Frame.Height/2 - 5, 5, 5), this, NSRectEdge.MinYEdge);
+				Popover.Show (new CGRect (20, this.Frame.Height/2 - 2.5, 5, 5), this, NSRectEdge.MinYEdge);
 		}
 
         public override void Layout()
@@ -121,17 +121,20 @@ namespace Xamarin.PropertyEditing.Mac
 			}
 		}
 
+
 		NSImage CreateSwatch (CommonColor color, CGSize size)
 		{
 			var board = new CICheckerboardGenerator () {
-				Color0 = CIColor.FromCGColor (color.ToCGColor ()),
-				Color1 = CIColor.FromCGColor (color.ToCGColor ()),
+				Color0 = CIColor.FromCGColor (color.Blend (CommonColor.White).ToCGColor ()),
+				Color1 = CIColor.FromCGColor (color.Blend (CommonColor.Black).ToCGColor ()),
 				Width = (float)Math.Min (size.Height / 2f, 10),
 				Center = new CIVector (new nfloat[] { 0, 0 }),
 			};
 
 			var context = new CIContext (null);
-			return new NSImage (context.CreateCGImage (board.OutputImage, new CGRect (0, 0, size.Width, size.Height)), size); 
+			var image = new NSImage (context.CreateCGImage (board.OutputImage, new CGRect (0, 0, size.Width, size.Height)), size);
+			context.Dispose ();
+			return image;
 		}
 
 		protected override void OnViewModelChanged (PropertyViewModel oldModel)
diff --git a/Xamarin.PropertyEditing.Mac/Controls/Custom/SolidColorBrushEditor.cs b/Xamarin.PropertyEditing.Mac/Controls/Custom/SolidColorBrushEditor.cs
index 84e16e9..936a4f9 100644
--- a/Xamarin.PropertyEditing.Mac/Controls/Custom/SolidColorBrushEditor.cs
+++ b/Xamarin.PropertyEditing.Mac/Controls/Custom/SolidColorBrushEditor.cs
@@ -236,7 +236,8 @@ namespace Xamarin.PropertyEditing.Mac
 			viewModel.Color = CommonColor.FromHSB (
 				Math.Min (360, Math.Max (0, color.Hue)),
 				Math.Min (1, Math.Max (0, saturation)),
-				Math.Min (1, Math.Max (0, brightness)));
+				Math.Min (1, Math.Max (0, brightness)),
+				color.A);
 		}
     }
 
@@ -307,7 +308,8 @@ namespace Xamarin.PropertyEditing.Mac
 			viewModel.Color = CommonColor.FromHSB (
 				Math.Max (0, Math.Min (360, hue)),
 				Math.Max (0, Math.Min (1, color.Saturation)),
-				Math.Max (0, Math.Min (1, color.Brightness)));
+				Math.Max (0, Math.Min (1, color.Brightness)),
+				color.A);
 		}
 
         public override void LayoutSublayers()
@@ -344,9 +346,27 @@ namespace Xamarin.PropertyEditing.Mac
 	public static class DrawingHelpers
 	{
 		public static CGColor ToCGColor (this CommonColor color)
-			=> new CGColor (color.R / 255f, color.G / 255f, color.B / 255f);
+			=> new CGColor (color.R / 255f, color.G / 255f, color.B / 255f, color.A / 255f);
 		public static CGColor ToCGColor (this CommonColor color, float alpha)
 			=> new CGColor (color.R / 255f, color.G / 255f, color.B / 255f, alpha);
+
+		public static CommonColor Blend (this CommonColor a, CommonColor b)
+		{
+			byte C (byte cb1, byte ab1, byte cb2) {
+				var c1 = cb1 / 255f;
+				var a1 = ab1 / 255f;
+				var c2 = cb2 / 255f;
+
+				var c = Math.Max (0, Math.Min (255, (c1 + c2 * (1 - a1)) * 255));
+				return (byte)c;
+			}
+
+			return new CommonColor (
+				C (a.R, a.A, b.R),
+				C (a.G, a.A, b.G),
+				C (a.B, a.A, b.B),
+				C (a.A, a.A, b.A));
+		}
 	}
 
 	class SolidColorBrushEditor : ColorEditorView