Support custom map previews.

Add map.png to the map archive.

OpenRA.Game/Map.cs

@@ -70,6 +70,7 @@ namespace OpenRA
 		public string Author;
 		public string Tileset;
 		public bool AllowStartUnitConfig = true;
+		public Bitmap CustomPreview;
 
 		[FieldLoader.LoadUsing("LoadOptions")]
 		public MapOptions Options;
@@ -226,6 +227,9 @@ namespace OpenRA
 				Save(path);
 
 			Uid = ComputeHash();
+
+			if (Container.Exists("map.png"))
+				CustomPreview = new Bitmap(Container.GetContent("map.png"));
 		}
 
 		public CPos[] GetSpawnPoints()

OpenRA.Game/MapCache.cs

@@ -107,7 +107,7 @@ namespace OpenRA
 				//       the next render cycle.
 				//   (d) Any partially written bytes from the next minimap is in an
 				//       unallocated area, and will be committed in the next cycle.
-				var bitmap = Minimap.RenderMapPreview(p.Map, true);
+				var bitmap = p.CustomPreview ?? Minimap.RenderMapPreview(p.Map, true);
 				p.Minimap = sheetBuilder.Add(bitmap);
 
 				lock (syncRoot)

OpenRA.Game/MapPreview.cs

@@ -33,6 +33,7 @@ namespace OpenRA
 		public int PlayerCount { get; private set; }
 		public List<CPos> SpawnPoints { get; private set; }
 		public Rectangle Bounds { get; private set; }
+		public Bitmap CustomPreview { get; private set; }
 		public Map Map { get; private set; }
 		public MapStatus Status { get; private set; }
 
@@ -85,6 +86,7 @@ namespace OpenRA
 			PlayerCount = m.Players.Count(x => x.Value.Playable);
 			Bounds = m.Bounds;
 			SpawnPoints = m.GetSpawnPoints().ToList();
+			CustomPreview = m.CustomPreview;
 			Status = MapStatus.Available;
 		}
 	}