CPF/CPF.Mac/Mac/CoreText/CTRunDelegateOperations.cs

using CPF.Mac.ObjCRuntime;
using System;
using System.Reflection;
using System.Runtime.InteropServices;

namespace CPF.Mac.CoreText
{
	[Since(3, 2)]
	public class CTRunDelegateOperations : IDisposable
	{
		internal GCHandle handle;

		protected CTRunDelegateOperations()
		{
			handle = GCHandle.Alloc(this);
		}

		public virtual void Dispose()
		{
		}

		public virtual float GetAscent()
		{
			return 0f;
		}

		public virtual float GetDescent()
		{
			return 0f;
		}

		public virtual float GetWidth()
		{
			return 0f;
		}

		internal CTRunDelegateCallbacks GetCallbacks()
		{
			CTRunDelegateCallbacks cTRunDelegateCallbacks = new CTRunDelegateCallbacks
			{
				version = CTRunDelegateVersion.Version1,
				dealloc = Deallocate
			};
			BindingFlags bindingAttr = BindingFlags.Instance | BindingFlags.Public;
			MethodInfo method;
			if ((method = GetType().GetMethod("GetAscent", bindingAttr)) != null && method.DeclaringType != typeof(CTRunDelegateOperations))
			{
				cTRunDelegateCallbacks.getAscent = GetAscent;
			}
			if ((method = GetType().GetMethod("GetDescent", bindingAttr)) != null && method.DeclaringType != typeof(CTRunDelegateOperations))
			{
				cTRunDelegateCallbacks.getDescent = GetDescent;
			}
			if ((method = GetType().GetMethod("GetWidth", bindingAttr)) != null && method.DeclaringType != typeof(CTRunDelegateOperations))
			{
				cTRunDelegateCallbacks.getWidth = GetWidth;
			}
			return cTRunDelegateCallbacks;
		}

		[MonoPInvokeCallback(typeof(CTRunDelegateDeallocateCallback))]
		private static void Deallocate(IntPtr refCon)
		{
			CTRunDelegateOperations operations = GetOperations(refCon);
			if (operations != null)
			{
				operations.Dispose();
				if (operations.handle.IsAllocated)
				{
					operations.handle.Free();
				}
				operations.handle = default(GCHandle);
			}
		}

		internal static CTRunDelegateOperations GetOperations(IntPtr refCon)
		{
			return GCHandle.FromIntPtr(refCon).Target as CTRunDelegateOperations;
		}

		[MonoPInvokeCallback(typeof(CTRunDelegateGetAscentCallback))]
		private static float GetAscent(IntPtr refCon)
		{
			return GetOperations(refCon)?.GetAscent() ?? 0f;
		}

		[MonoPInvokeCallback(typeof(CTRunDelegateGetDescentCallback))]
		private static float GetDescent(IntPtr refCon)
		{
			return GetOperations(refCon)?.GetDescent() ?? 0f;
		}

		[MonoPInvokeCallback(typeof(CTRunDelegateGetWidthCallback))]
		private static float GetWidth(IntPtr refCon)
		{
			return GetOperations(refCon)?.GetWidth() ?? 0f;
		}
	}
}