Paints a gradient fill that varies along the area defined by the provided starting and ending circles.
Original signature is 'void CGContextDrawRadialGradient( CGContextRef context, CGGradientRef gradient, CGPoint startCenter, CGFloat startRadius, CGPoint endCenter, CGFloat endRadius, CGGradientDrawingOptions options );'
Available in Mac OS X v10.5 and later.

C# | Visual Basic | Visual C++ |
public static void DrawRadialGradient( IntPtr context, IntPtr gradient, CGPoint startCenter, CGFloat startRadius, CGPoint endCenter, CGFloat endRadius, CGGradientDrawingOptions options )

- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)