Added C# binding for SKData.Create without copy

binding/Binding/SKData.cs

@@ -14,10 +14,26 @@ using System.Text;
 
 namespace SkiaSharp
 {
+	// public delegates
+	public delegate void SKDataReleaseDelegate (IntPtr address, object context);
+
+	// internal proxy delegates
+	[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
+	internal delegate void SKDataReleaseDelegateInternal (IntPtr address, IntPtr context);
+
 	public class SKData : SKObject
 	{
 		private const int CopyBufferSize = 8192;
 
+		// so the GC doesn't collect the delegate
+		private static readonly SKDataReleaseDelegateInternal releaseDelegateInternal;
+		private static readonly IntPtr releaseDelegate;
+		static SKData ()
+		{
+			releaseDelegateInternal = new SKDataReleaseDelegateInternal (ReleaseInternal);
+			releaseDelegate = Marshal.GetFunctionPointerForDelegate (releaseDelegateInternal);
+		}
+
 		protected override void Dispose (bool disposing)
 		{
 			if (Handle != IntPtr.Zero && OwnsHandle) {
@@ -65,6 +81,26 @@ namespace SkiaSharp
 			}
 		}
 
+		public static SKData Create (IntPtr address, int length)
+		{
+			return Create (address, length, null, null);
+		}
+
+		public static SKData Create (IntPtr address, int length, SKDataReleaseDelegate releaseProc)
+		{
+			return Create (address, length, releaseProc, null);
+		}
+
+		public static SKData Create (IntPtr address, int length, SKDataReleaseDelegate releaseProc, object context)
+		{
+			if (releaseProc == null) {
+				return GetObject<SKData> (SkiaApi.sk_data_new_with_proc (address, (IntPtr) length, IntPtr.Zero, IntPtr.Zero));
+			} else {
+				var ctx = new NativeDelegateContext (context, releaseProc);
+				return GetObject<SKData> (SkiaApi.sk_data_new_with_proc (address, (IntPtr) length, releaseDelegate, ctx.NativeContext));
+			}
+		}
+
 		public static SKData FromMallocMemory (IntPtr bytes, ulong length)
 		{
 			if (SizeOf <IntPtr> () == 4 && length > UInt32.MaxValue)
@@ -135,6 +171,17 @@ namespace SkiaSharp
 			}
 		}
 
+		// internal proxy
+		#if __IOS__
+		[ObjCRuntime.MonoPInvokeCallback (typeof (SKDataReleaseDelegateInternal))]
+		#endif
+		private static void ReleaseInternal (IntPtr address, IntPtr context)
+		{
+			using (var ctx = NativeDelegateContext.Unwrap (context)) {
+				ctx.GetDelegate<SKDataReleaseDelegate> () (address, ctx.ManagedContext);
+			}
+		}
+
 		private class SKDataStream : UnmanagedMemoryStream
 		{
 			private SKData host;

binding/Binding/SkiaApi.cs

@@ -810,6 +810,9 @@ namespace SkiaSharp
 		public extern static sk_data_t sk_data_new_from_file(string path);
 		[DllImport(SKIA, CallingConvention = CallingConvention.Cdecl)]
 		public extern static sk_data_t sk_data_new_from_stream(sk_stream_t stream, IntPtr length);
+		[DllImport(SKIA, CallingConvention = CallingConvention.Cdecl)]
+		public extern static sk_data_t sk_data_new_with_proc(IntPtr ptr, IntPtr length, IntPtr proc, IntPtr ctx);
+
 		[DllImport(SKIA, CallingConvention = CallingConvention.Cdecl)]
 		public extern static void sk_data_unref(sk_data_t d);
 		[DllImport(SKIA, CallingConvention = CallingConvention.Cdecl)]

externals/skia

@@ -1 +1 @@
-Subproject commit 379184f0ab1dfc9f2364043b70c5f65b9a3bc084
+Subproject commit 009e372b71021c6bbe5a05ec96843b2c2d554507

tests/Tests/SKDataTest.cs

@@ -17,6 +17,27 @@ namespace SkiaSharp.Tests
 			Assert.AreEqual(OddData, data.ToArray());
 		}
 
+		[Test]
+		public void ReleaseDataWasInvoked()
+		{
+			bool released = false;
+
+			var onRelease = new SKDataReleaseDelegate((addr, ctx) => {
+				Marshal.FreeCoTaskMem(addr);
+				released = true;
+				Assert.AreEqual("RELEASING!", ctx);
+			});
+
+			var memory = Marshal.AllocCoTaskMem(10);
+
+			using (var data = SKData.Create(memory, 10, onRelease, "RELEASING!")) {
+				Assert.AreEqual(memory, data.Data);
+				Assert.AreEqual(10, data.Size);
+			}
+
+			Assert.True(released, "The SKDataReleaseDelegate was not called.");
+		}
+
 		[Test]
 		[Ignore("Doesn't work as it relies on memory being overwritten by an external process.")]
 		public void DataDisposedReturnsInvalidStream()