Introduce TerrainTemplatePreviewWidget.

OpenRA.Game/Graphics/Theater.cs

@@ -21,9 +21,11 @@ namespace OpenRA.Graphics
 		SheetBuilder sheetBuilder;
 		Dictionary<ushort, Sprite[]> templates;
 		Sprite missingTile;
+		TileSet tileset;
 
 		public Theater(TileSet tileset)
 		{
+			this.tileset = tileset;
 			var allocated = false;
 			Func<Sheet> allocate = () =>
 			{
@@ -69,6 +71,35 @@ namespace OpenRA.Graphics
 			return template[r.Index];
 		}
 
+		public Rectangle TemplateBounds(TerrainTemplateInfo template, Size tileSize, TileShape tileShape)
+		{
+			Rectangle? templateRect = null;
+
+			var i = 0;
+			for (var y = 0; y < template.Size.Y; y++)
+			{
+				for (var x = 0; x < template.Size.X; x++)
+				{
+					var tile = new TerrainTile(template.Id, (byte)(i++));
+					var tileInfo = tileset.GetTileInfo(tile);
+
+					// Empty tile
+					if (tileInfo == null)
+						continue;
+
+					var sprite = TileSprite(tile);
+					var u = tileShape == TileShape.Rectangle ? x : (x - y) / 2f;
+					var v = tileShape == TileShape.Rectangle ? y : (x + y) / 2f;
+
+					var tl = new float2(u * tileSize.Width, (v - 0.5f * tileInfo.Height) * tileSize.Height) - 0.5f * sprite.size;
+					var rect = new Rectangle((int)(tl.X + sprite.offset.X), (int)(tl.Y + sprite.offset.Y), (int)sprite.size.X, (int)sprite.size.Y);
+					templateRect = templateRect.HasValue ? Rectangle.Union(templateRect.Value, rect) : rect;
+				}
+			}
+
+			return templateRect.HasValue ? templateRect.Value : Rectangle.Empty;
+		}
+
 		public Sheet Sheet { get { return sheetBuilder.Current; } }
 	}
 }