Shift temporary owner-change logic from D2k to Common.

OpenRA.Mods.Common/OpenRA.Mods.Common.csproj

@@ -315,6 +315,7 @@
     <Compile Include="Traits\Conditions\GrantExternalConditionToCrusher.cs" />
     <Compile Include="Traits\Conditions\GrantRandomCondition.cs" />
     <Compile Include="Traits\Contrail.cs" />
+    <Compile Include="Traits\TemporaryOwnerManager.cs" />
     <Compile Include="Traits\TooltipDescription.cs" />
     <Compile Include="Traits\Health.cs" />
     <Compile Include="Traits\HitShape.cs" />
@@ -593,6 +594,7 @@
     <Compile Include="UtilityCommands\ExtractZeroBraneStudioLuaAPI.cs" />
     <Compile Include="UtilityCommands\ExtractTraitDocsCommand.cs" />
     <Compile Include="UtilityCommands\ExtractWeaponDocsCommand.cs" />
+    <Compile Include="Warheads\ChangeOwnerWarhead.cs" />
     <Compile Include="Widgets\Logic\MusicHotkeyLogic.cs" />
     <Compile Include="WorldExtensions.cs" />
     <Compile Include="UtilityCommands\GetMapHashCommand.cs" />

OpenRA.Mods.Common/Traits/TemporaryOwnerManager.cs

@@ -0,0 +1,85 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2018 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, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Drawing;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("Interacts with the ChangeOwner warhead.",
+		"Displays a bar how long this actor is affected and reverts back to the old owner on temporary changes.")]
+	public class TemporaryOwnerManagerInfo : ITraitInfo
+	{
+		public readonly Color BarColor = Color.Orange;
+
+		public object Create(ActorInitializer init) { return new TemporaryOwnerManager(init.Self, this); }
+	}
+
+	public class TemporaryOwnerManager : ISelectionBar, ITick, ISync, INotifyOwnerChanged
+	{
+		readonly TemporaryOwnerManagerInfo info;
+
+		Player originalOwner;
+		Player changingOwner;
+
+		[Sync] int remaining = -1;
+		int duration;
+
+		public TemporaryOwnerManager(Actor self, TemporaryOwnerManagerInfo info)
+		{
+			this.info = info;
+			originalOwner = self.Owner;
+		}
+
+		public void ChangeOwner(Actor self, Player newOwner, int duration)
+		{
+			remaining = this.duration = duration;
+			changingOwner = newOwner;
+			self.ChangeOwner(newOwner);
+		}
+
+		void ITick.Tick(Actor self)
+		{
+			if (!self.IsInWorld)
+				return;
+
+			if (--remaining == 0)
+			{
+				changingOwner = originalOwner;
+				self.ChangeOwner(originalOwner);
+				self.CancelActivity(); // Stop shooting, you have got new enemies
+			}
+		}
+
+		void INotifyOwnerChanged.OnOwnerChanged(Actor self, Player oldOwner, Player newOwner)
+		{
+			if (changingOwner == null || changingOwner != newOwner)
+				originalOwner = newOwner; // It wasn't a temporary change, so we need to update here
+			else
+				changingOwner = null; // It was triggered by this trait: reset
+		}
+
+		float ISelectionBar.GetValue()
+		{
+			if (remaining <= 0)
+				return 0;
+
+			return (float)remaining / duration;
+		}
+
+		Color ISelectionBar.GetColor()
+		{
+			return info.BarColor;
+		}
+
+		bool ISelectionBar.DisplayWhenEmpty { get { return false; } }
+	}
+}

OpenRA.Mods.Common/Warheads/ChangeOwnerWarhead.cs

@@ -0,0 +1,53 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2018 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, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Collections.Generic;
+using OpenRA.Mods.Common.Traits;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Warheads
+{
+	[Desc("Interacts with the TemporaryOwnerManager trait.")]
+	public class ChangeOwnerWarhead : Warhead
+	{
+		[Desc("Duration of the owner change (in ticks). Set to 0 to make it permanent.")]
+		public readonly int Duration = 0;
+
+		public readonly WDist Range = WDist.FromCells(1);
+
+		public override void DoImpact(Target target, Actor firedBy, IEnumerable<int> damageModifiers)
+		{
+			var actors = target.Type == TargetType.Actor ? new[] { target.Actor } :
+				firedBy.World.FindActorsInCircle(target.CenterPosition, Range);
+
+			foreach (var a in actors)
+			{
+				// Don't do anything on friendly fire
+				if (a.Owner == firedBy.Owner)
+					continue;
+
+				if (Duration == 0)
+					a.ChangeOwner(firedBy.Owner); // Permanent
+				else
+				{
+					var tempOwnerManager = a.TraitOrDefault<TemporaryOwnerManager>();
+					if (tempOwnerManager == null)
+						continue;
+
+					tempOwnerManager.ChangeOwner(a, firedBy.Owner, Duration);
+				}
+
+				// Stop shooting, you have new enemies
+				a.CancelActivity();
+			}
+		}
+	}
+}