Convert to 32bbp internally in FastCopyIntoSprite.

This avoids the need for callers to ensure the pixel format is correct, but ensures that the copying succeeds when the format is different.

OpenRA.Game/Graphics/Util.cs

@@ -64,9 +64,15 @@ namespace OpenRA.Graphics
 
 		public static void FastCopyIntoSprite(Sprite dest, Bitmap src)
 		{
+			var createdTempBitmap = false;
 			if (src.PixelFormat != PixelFormat.Format32bppArgb)
-				throw new ArgumentException("src must have a PixelFormat of Format32bppArgb", "src");
+			{
+				src = src.CloneWith32bbpArgbPixelFormat();
+				createdTempBitmap = true;
+			}
 
+			try
+			{
 				var data = dest.Sheet.GetData();
 				var dataStride = dest.Sheet.Size.Width * 4;
 				var x = dest.Bounds.Left * 4;
@@ -80,6 +86,12 @@ namespace OpenRA.Graphics
 					Marshal.Copy(IntPtr.Add(bd.Scan0, row * bd.Stride), data, (y + row) * dataStride + x, width);
 				src.UnlockBits(bd);
 			}
+			finally
+			{
+				if (createdTempBitmap)
+					src.Dispose();
+			}
+		}
 
 		public static float[] IdentityMatrix()
 		{

OpenRA.Game/Map/Map.cs

@@ -392,16 +392,8 @@ namespace OpenRA
 			DefaultSubCell = (SubCell)Game.ModData.Manifest.SubCellDefaultIndex;
 
 			if (Container.Exists("map.png"))
-			{
 				using (var dataStream = Container.GetContent("map.png"))
 					CustomPreview = new Bitmap(dataStream);
-				if (CustomPreview.PixelFormat != PixelFormat.Format32bppArgb)
-				{
-					var original = CustomPreview;
-					CustomPreview = original.CloneWith32bbpArgbPixelFormat();
-					original.Dispose();
-				}
-			}
 
 			PostInit();
 

OpenRA.Game/Map/MapPreview.cs

@@ -156,12 +156,6 @@ namespace OpenRA
 						SpawnPoints = spawns;
 
 						CustomPreview = new Bitmap(new MemoryStream(Convert.FromBase64String(r.minimap)));
-						if (CustomPreview.PixelFormat != PixelFormat.Format32bppArgb)
-						{
-							var original = CustomPreview;
-							CustomPreview = original.CloneWith32bbpArgbPixelFormat();
-							original.Dispose();
-						}
 					}
 					catch (Exception) { }