NSGraphicsContext: create -CGContext methods

Create methods which allow a graphics context to be created with a
CGContext as an equivalent to a graphics port. The context set through
this property will be used in gnustep-back.

Headers/AppKit/NSGraphicsContext.h

@@ -50,6 +50,8 @@
 @class NSBitmapImageRep;
 @class NSGradient;
 
+typedef struct CGContext *CGContextRef;
+
 /*
  * Backing Store Types
  */
@@ -202,6 +204,12 @@ typedef enum _GSColorSpace
                                                 flipped: (BOOL)flag;
 #endif
 
+#if OS_API_VERSION(MAC_OS_X_VERSION_10_10, GS_API_LATEST)
+- (CGContextRef) CGContext;
++ (NSGraphicsContext *) graphicsContextWithCGContext: (CGContextRef)ctx
+                                             flipped: (BOOL)flipped;
+#endif
+
 - (NSDictionary *) attributes;
 - (void *) graphicsPort;
 
@@ -530,7 +538,6 @@ transform between current user space and image space for this image.</desc>
             fromPoint: (NSPoint)startPoint
               toPoint: (NSPoint)endPoint
               options: (NSUInteger)options;
-
 @end
 
 /* NSGraphicContext constants */

Source/NSGraphicsContext.m

@@ -232,6 +232,13 @@ NSGraphicsContext	*GSCurrentContext(void)
   return new;
 }
 
++ (NSGraphicsContext *)graphicsContextWithCGContext: (CGContextRef)context
+					    flipped: (BOOL)flipped
+{
+  return [NSGraphicsContext graphicsContextWithGraphicsPort: (void *)context
+						    flipped: flipped];
+}
+
 + (void) restoreGraphicsState
 {
   NSGraphicsContext *ctxt;
@@ -355,6 +362,11 @@ NSGraphicsContext	*GSCurrentContext(void)
   return _graphicsPort;
 }
 
+- (CGContextRef)CGContext
+{
+  return (CGContextRef)[self graphicsPort];
+}
+
 - (BOOL) isDrawingToScreen
 {
   return NO;