split Target out into its own file

OpenRA.Game/Traits/Target.cs

@@ -0,0 +1,47 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2010 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made 
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see LICENSE.
+ */
+#endregion
+
+namespace OpenRA.Traits
+{
+	public struct Target		// a target: either an actor, or a fixed location.
+	{
+		Actor actor;
+		Player owner;
+		int2 pos;
+		bool valid;
+
+		public static Target FromActor(Actor a)
+		{
+			return new Target
+			{
+				actor = a,
+				valid = (a != null),
+				owner = (a != null) ? a.Owner : null
+			};
+		}
+		public static Target FromPos(int2 p) { return new Target { pos = p, valid = true }; }
+		public static Target FromCell(int2 c) { return new Target { pos = Util.CenterOfCell(c), valid = true }; }
+		public static Target FromOrder(Order o)
+		{
+			return o.TargetActor != null
+				? Target.FromActor(o.TargetActor)
+				: Target.FromCell(o.TargetLocation);
+		}
+
+		public static readonly Target None = new Target();
+
+		public bool IsValid { get { return valid && (actor == null || (actor.IsInWorld && actor.Owner == owner)); } }
+		public int2 PxPosition { get { return IsActor ? actor.Trait<IHasLocation>().PxPosition : pos; } }
+		public int2 CenterLocation { get { return PxPosition; } }
+
+		public Actor Actor { get { return IsActor ? actor : null; } }
+		public bool IsActor { get { return actor != null && !actor.Destroyed; } }
+	}
+}