Add ISpriteSequence.Bounds and Animation(WithOffset).ScreenBounds.

The bounds define the smallest Rectangle that covers all frames within a sequence.

OpenRA.Game/Graphics/AnimationWithOffset.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 
 namespace OpenRA.Graphics
 {
@@ -44,6 +45,14 @@ namespace OpenRA.Graphics
 			return Animation.Render(center, offset, z, pal, scale);
 		}
 
+		public Rectangle ScreenBounds(Actor self, WorldRenderer wr, float scale)
+		{
+			var center = self.CenterPosition;
+			var offset = OffsetFunc != null ? OffsetFunc() : WVec.Zero;
+
+			return Animation.ScreenBounds(wr, center, offset, scale);
+		}
+
 		public static implicit operator AnimationWithOffset(Animation a)
 		{
 			return new AnimationWithOffset(a, null, null, null);