Remove unnecessary edge inset for vertically scrolling groups; Fixes … (#13380) fixes #13347

* Remove unnecessary edge inset for vertically scrolling groups; Fixes #13347

* Fix edge insets in horizontally-scrolling groups

Author: hartez

Xamarin.Forms.Controls/GalleryPages/CollectionViewGalleries/GroupingGalleries/GridGrouping.xaml

@@ -9,7 +9,7 @@
         <CollectionView x:Name="CollectionView" IsGrouped="True" Header="This is a header" Footer="This is a footer.">
 
             <CollectionView.ItemsLayout>
-                <GridItemsLayout Span="2" Orientation="Vertical"></GridItemsLayout>
+                <GridItemsLayout Span="2" HorizontalItemSpacing="5" Orientation="Vertical"></GridItemsLayout>
             </CollectionView.ItemsLayout>
 
             <CollectionView.ItemTemplate>

Xamarin.Forms.Platform.iOS/CollectionView/GroupableItemsViewController.cs

@@ -217,34 +217,24 @@ internal UIEdgeInsets GetInsetForSection(ItemsViewLayout itemsViewLayout,
 				return uIEdgeInsets;
 			}
 
-			// If we're grouping, we'll need to inset the sections to maintain the item spacing between the 
-			// groups and/or their group headers/footers
+			// If we're grouping, we'll need to inset the sections to maintain the spacing between the 
+			// groups and their group headers/footers
 
-			var itemsLayout = ItemsView.ItemsLayout;
-			var scrollDirection = itemsViewLayout.ScrollDirection;
-			nfloat lineSpacing = itemsViewLayout.GetMinimumLineSpacingForSection(collectionView, itemsViewLayout, section);
+			nfloat spacing = itemsViewLayout.GetMinimumLineSpacingForSection(collectionView, itemsViewLayout, section);
 
-			if (itemsLayout is GridItemsLayout)
-			{
-				nfloat itemSpacing = itemsViewLayout.GetMinimumInteritemSpacingForSection(collectionView, itemsViewLayout, section);
-
-				if (scrollDirection == UICollectionViewScrollDirection.Horizontal)
-				{
-					return new UIEdgeInsets(itemSpacing + uIEdgeInsets.Top, lineSpacing + uIEdgeInsets.Left,
-						uIEdgeInsets.Bottom, uIEdgeInsets.Right);
-				}
+			var top = uIEdgeInsets.Top;
+			var left = uIEdgeInsets.Left;
 
-				return new UIEdgeInsets(lineSpacing + uIEdgeInsets.Top, itemSpacing + uIEdgeInsets.Left,
-					uIEdgeInsets.Bottom, uIEdgeInsets.Right);
+			if (itemsViewLayout.ScrollDirection == UICollectionViewScrollDirection.Horizontal)
+			{
+				left += spacing;
 			}
-
-			if (scrollDirection == UICollectionViewScrollDirection.Horizontal)
+			else
 			{
-				return new UIEdgeInsets(uIEdgeInsets.Top, lineSpacing + uIEdgeInsets.Left,
-					uIEdgeInsets.Bottom, uIEdgeInsets.Right);
+				top += spacing;
 			}
 
-			return new UIEdgeInsets(lineSpacing + uIEdgeInsets.Top, uIEdgeInsets.Left,
+			return new UIEdgeInsets(top, left,
 				uIEdgeInsets.Bottom, uIEdgeInsets.Right);
 		}