Add `PtrToStringUTF8()` for `byte *`

SDL3-CS/SDL3.cs

@@ -0,0 +1,29 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Runtime.InteropServices;
+
+namespace SDL
+{
+    public static unsafe partial class SDL3
+    {
+        /// <summary>
+        /// Allocates a managed <c>string</c> and copies all characters up to the first null character from an unmanaged UTF-8 string into it.
+        /// </summary>
+        /// <param name="ptr">The address of the first character of the unmanaged string.</param>
+        /// <param name="free">Whether to free the pointer after copying the string.</param>
+        /// <returns>
+        /// A managed string that holds a copy of the unmanaged string if the value of the <paramref name="ptr"/> parameter is not <c>null</c>; otherwise, this method returns <c>null</c>.
+        /// </returns>
+        public static string? PtrToStringUTF8(byte* ptr, bool free = false)
+        {
+            string? s = Marshal.PtrToStringUTF8((IntPtr)ptr);
+
+            if (free)
+                SDL_free(ptr);
+
+            return s;
+        }
+    }
+}