PNext<T>, structs with stype passed by refv0.5.0

1 files changed, 46 insertions, 0 deletions

diff --git a/vulkan/PNext.cs b/vulkan/PNext.cs
new file mode 100644
index 0000000..783e757
--- /dev/null
+++ b/vulkan/PNext.cs
@@ -0,0 +1,46 @@
+// This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
+//
+// Copyright (c) 2022 JP Bruyère
+using System;
+using System.Linq;
+using System.Runtime.InteropServices;
+
+namespace Vulkan
+{
+    /// <summary>
+    /// Helper class to construct pnext chain
+    /// </summary>
+	public class PNext<T> : IDisposable where T : struct
+	{
+		IntPtr handle;
+		/// <summary>
+		/// Allocate on HGlobal a new structure of type T, ensure instance is Disposed.
+		/// </summary>
+		public PNext () {
+			init();
+		}
+		/// <summary>
+		/// Allocate on HGlobal a new structure of type T and set the pNext field,
+		/// ensure instance is Disposed.
+		/// </summary>
+		public PNext (IntPtr pNext) {
+			init();
+			Marshal.WriteIntPtr(handle + 4, pNext);
+		}
+		void init() {
+			handle = Marshal.AllocHGlobal(Marshal.SizeOf<T>());
+			Type t = typeof(T);
+			StructureTypeAttribute st = (StructureTypeAttribute)t.GetCustomAttributes(typeof(StructureTypeAttribute), false).FirstOrDefault();
+			Marshal.WriteInt32(handle, st.StructureType);
+		}
+		/// <summary>
+		/// Get value of T
+		/// </summary>
+		public T Val => Marshal.PtrToStructure<T> (handle);
+		public static implicit operator IntPtr(PNext<T> pn) => pn.handle;
+		public void Dispose()
+		{
+			Marshal.FreeHGlobal(handle);
+		}
+	}
+}