[OSX] Reintroduce Cocoa System.Drawing support

The old Cocoa backend for System.Drawing appears to still work.  You must
pass in a NSView.Handle while in the DrawRect method, or with lockFocus
called to prepare the NSGraphicsContext.

mcs/class/System.Drawing/System.Drawing.dll.sources

@@ -8,7 +8,7 @@ System.Drawing/BufferedGraphics.cs
 System.Drawing/BufferedGraphicsManager.cs
 System.Drawing/BufferedGraphicsContext.cs
 System.Drawing/CharacterRange.cs
-System.Drawing/carbonFunctions.cs
+System.Drawing/macFunctions.cs
 System.Drawing/ColorConverter.cs
 System.Drawing/Color.cs
 System.Drawing/ColorTranslator.cs

mcs/class/System.Drawing/System.Drawing/Graphics.cs

@@ -49,7 +49,7 @@ public sealed class Graphics : MarshalByRefObject, IDisposable
 #endif
 	{
 		internal IntPtr nativeObject = IntPtr.Zero;
-		internal CarbonContext context;
+		internal IMacContext maccontext;
 		private bool disposed = false;
 		private static float defDpiX = 0;
 		private static float defDpiY = 0;
@@ -190,6 +190,8 @@ public void CopyFromScreen (int sourceX, int sourceY, int destinationX, int dest
 				CopyFromScreenX11 (sourceX, sourceY, destinationX, destinationY, blockRegionSize, copyPixelOperation);
 			} else if (GDIPlus.UseCarbonDrawable) {
 				CopyFromScreenMac (sourceX, sourceY, destinationX, destinationY, blockRegionSize, copyPixelOperation);
+			} else if (GDIPlus.UseCocoaDrawable) {
+				CopyFromScreenMac (sourceX, sourceY, destinationX, destinationY, blockRegionSize, copyPixelOperation);
 			} else {
 				CopyFromScreenWin32 (sourceX, sourceY, destinationX, destinationY, blockRegionSize, copyPixelOperation);
 			}
@@ -293,11 +295,11 @@ public void Dispose ()
 		{
 			Status status;
 			if (! disposed) {
-				if (GDIPlus.UseCarbonDrawable && context.ctx != IntPtr.Zero) {
+				if (GDIPlus.UseCarbonDrawable || GDIPlus.UseCocoaDrawable) {
 					Flush ();
-					Carbon.CGContextSynchronize (context.ctx);
-					Carbon.ReleaseContext (context.port, context.ctx);
+					maccontext.Release ();
 				}
+
 				status = GDIPlus.GdipDeleteGraphics (nativeObject);
 				nativeObject = IntPtr.Zero;
 				GDIPlus.CheckStatus (status);
@@ -1681,8 +1683,9 @@ public void Flush (FlushIntention intention)
 
 			Status status = GDIPlus.GdipFlush (nativeObject, intention);
                         GDIPlus.CheckStatus (status);                    
-			if (GDIPlus.UseCarbonDrawable && context.ctx != IntPtr.Zero)
-				Carbon.CGContextSynchronize (context.ctx);
+
+			if (maccontext != null)
+				maccontext.Synchronize ();
 		}
 
 		[EditorBrowsable (EditorBrowsableState.Advanced)]		
@@ -1714,12 +1717,22 @@ public static Graphics FromHwnd (IntPtr hwnd)
 		{
 			IntPtr graphics;
 
+			if (GDIPlus.UseCocoaDrawable) {
+				CocoaContext context = MacSupport.GetCGContextForNSView (hwnd);
+				GDIPlus.GdipCreateFromContext_macosx (context.ctx, context.width, context.height, out graphics);
+
+				Graphics g = new Graphics (graphics);
+				g.maccontext = context;
+
+				return g;
+			}
+
 			if (GDIPlus.UseCarbonDrawable) {
-				CarbonContext context = Carbon.GetCGContextForView (hwnd);
+				CarbonContext context = MacSupport.GetCGContextForView (hwnd);
 				GDIPlus.GdipCreateFromContext_macosx (context.ctx, context.width, context.height, out graphics);
 
 				Graphics g = new Graphics (graphics);
-				g.context = context;
+				g.maccontext = context;
 
 				return g;
 			}

mcs/class/System.Drawing/System.Drawing/gdipFunctions.cs

@@ -61,6 +61,7 @@ internal class GDIPlus {
 		public static IntPtr Display = IntPtr.Zero;
 		public static bool UseX11Drawable = false;
 		public static bool UseCarbonDrawable = false;
+		public static bool UseCocoaDrawable = false;
 
 		#region gdiplus.dll functions
 
@@ -138,12 +139,12 @@ static GDIPlus ()
 
 		static public bool RunningOnWindows ()
 		{
-			return !UseX11Drawable && !UseCarbonDrawable;
+			return !UseX11Drawable && !UseCarbonDrawable && !UseCocoaDrawable;
 		}
 
 		static public bool RunningOnUnix ()
 		{
-			return UseX11Drawable || UseCarbonDrawable;
+			return UseX11Drawable || UseCarbonDrawable || UseCocoaDrawable;
 		}
 
 		// Copies a Ptr to an array of Points and releases the memory

mcs/class/System.Drawing/System.Drawing/carbonFunctions.cs → mcs/class/System.Drawing/System.Drawing/macFunctions.cs

@@ -36,9 +36,9 @@ namespace System.Drawing {
 
 	[SuppressUnmanagedCodeSecurity]
 #if NET_2_0
-	internal static class Carbon {
+	internal static class MacSupport {
 #else
-	internal sealed class Carbon {
+	internal sealed class MacSupport {
 #endif
 		internal static Hashtable contextReference = new Hashtable ();
 		internal static object lockobj = new object ();
@@ -52,7 +52,7 @@ internal sealed class Carbon {
 		internal static int debug_threshold = 1;
 #endif
 
-		static Carbon () {
+		static MacSupport () {
 			foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies ()) {
 				if (String.Equals (asm.GetName ().Name, "System.Windows.Forms")) {
 					Type driver_type = asm.GetType ("System.Windows.Forms.XplatUICarbon");
@@ -63,6 +63,16 @@ internal sealed class Carbon {
 			}
 		}
 
+		internal static CocoaContext GetCGContextForNSView (IntPtr handle) {
+			IntPtr graphicsContext = objc_msgSend (objc_getClass ("NSGraphicsContext"), sel_registerName ("currentContext"));
+			IntPtr ctx = objc_msgSend (graphicsContext, sel_registerName ("graphicsPort"));
+			Rect bounds = new Rect ();
+
+			objc_msgSend_stret (ref bounds, handle, sel_registerName ("bounds"));
+
+			return new CocoaContext (ctx, (int) bounds.size.width, (int) bounds.size.height);
+		}
+
 		internal static CarbonContext GetCGContextForView (IntPtr handle) {
 			IntPtr context = IntPtr.Zero;
 			IntPtr port = IntPtr.Zero;
@@ -289,7 +299,7 @@ internal struct QDRect
 		public short right;
 	}
 
-	internal struct CarbonContext
+	internal struct CarbonContext : IMacContext
 	{
 		public IntPtr port;
 		public IntPtr ctx;
@@ -303,5 +313,44 @@ public CarbonContext (IntPtr port, IntPtr ctx, int width, int height)
 			this.width = width;
 			this.height = height;
 		}
+
+		public void Synchronize ()
+		{
+			MacSupport.CGContextSynchronize (ctx);
+		}
+
+		public void Release ()
+		{
+			MacSupport.ReleaseContext (port, ctx);
+		}
+	}
+
+	internal struct CocoaContext : IMacContext
+	{
+		public IntPtr ctx;
+		public int width;
+		public int height;
+
+		public CocoaContext (IntPtr ctx, int width, int height)
+		{
+			this.ctx = ctx;
+			this.width = width;
+			this.height = height;
+		}
+
+		public void Synchronize ()
+		{
+			MacSupport.CGContextSynchronize (ctx);
+		}
+
+		public void Release ()
+		{
+		}
+	}
+
+	internal interface IMacContext
+	{
+		void Synchronize ();
+		void Release ();
 	}
 }