[Fix #357] Update AreaEditor8a.cs to save AreaSettings

pkNX.WinForms/Subforms/AreaEditor8a.cs

@@ -11,6 +11,8 @@
 using pkNX.Structures.FlatBuffers.Arceus;
 using static pkNX.Structures.Species;
 using Util = pkNX.Randomization.Util;
+using FlatSharp;
+using System.Buffers;
 
 namespace pkNX.WinForms.Subforms;
 
@@ -163,9 +165,38 @@ private void B_Save_Click(object sender, EventArgs e)
 
     private void AreaEditor8a_FormClosing(object sender, FormClosingEventArgs e)
     {
-        if (Save)
+        if (Save){
             SaveArea();
-        else
+            SaveSettings();
+        }
+        else {
             Resident.CancelEdits();
+        }
+    }
+
+    private void SaveSettings()
+    {
+        TryWrite("bin/field/resident/AreaSettings.bin", Settings);
+    }
+
+    private static byte[] Write<T>(T obj) where T : class, IFlatBufferSerializable<T>
+    {
+        var pool = ArrayPool<byte>.Shared;
+        var serializer = obj.Serializer;
+        var data = pool.Rent(serializer.GetMaxSize(obj));
+        var len = serializer.Write(data, obj);
+        var result = data.AsSpan(0, len).ToArray();
+        pool.Return(data);
+        return result;
+    }
+
+    private void TryWrite<T>(string path, T obj) where T : class, IFlatBufferSerializable<T>
+    {
+        var index = Resident.GetIndexFull(path);
+        if (index == -1)
+            return;
+
+        byte[] result = Write(obj);
+        Resident[index] = result;
     }
 }