Simplify PlacementMode.Center

src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs

@@ -464,25 +464,21 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
                 positionerParameters.Anchor = PopupAnchor.TopLeft;
                 positionerParameters.Gravity = PopupGravity.BottomRight;
             }
-            else if (placement == PlacementMode.Center)
+            else
             {
-                // Start with top left position, and add offset to move it to the center
+                if (target == null)
-                var anchorRectangle = GetAnchorRectangle(topLevel, target, rect);
+                    throw new InvalidOperationException("Placement mode is not Pointer and PlacementTarget is null");
-                positionerParameters.AnchorRectangle = anchorRectangle; 
+                var matrix = target.TransformToVisual(topLevel);
-                positionerParameters.Anchor = PopupAnchor.TopLeft;
+                if (matrix == null)
-                positionerParameters.Gravity = PopupGravity.BottomRight;
-
-                var targetSize = positionerParameters.Size;
-                if (targetSize != default)
                 {
-                    positionerParameters.Offset += new Point(
+                    if (target.GetVisualRoot() == null)
-                        (anchorRectangle.Width - targetSize.Width) / 2,
+                        throw new InvalidOperationException("Target control is not attached to the visual tree");
-                        (anchorRectangle.Height - targetSize.Height) / 2);
+                    throw new InvalidOperationException("Target control is not in the same tree as the popup parent");
                 }
-            }
+
-            else
+                var bounds = new Rect(default, target.Bounds.Size);
-            {
+                var anchorRect = rect ?? bounds;
-                positionerParameters.AnchorRectangle = GetAnchorRectangle(topLevel, target, rect);
+                positionerParameters.AnchorRectangle =  anchorRect.Intersect(bounds).TransformToAABB(matrix.Value);
 
                 var parameters = placement switch
                 {
@@ -490,6 +486,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
                     PlacementMode.Right => (PopupAnchor.Right, PopupGravity.Right),
                     PlacementMode.Left => (PopupAnchor.Left, PopupGravity.Left),
                     PlacementMode.Top => (PopupAnchor.Top, PopupGravity.Top),
+                    PlacementMode.Center => (PopupAnchor.None, PopupGravity.None),
                     PlacementMode.AnchorAndGravity => (anchor, gravity),
                     PlacementMode.TopEdgeAlignedRight => (PopupAnchor.TopRight, PopupGravity.TopLeft),
                     PlacementMode.TopEdgeAlignedLeft => (PopupAnchor.TopLeft, PopupGravity.TopRight),
@@ -532,23 +529,6 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
                 }
             }
         }
-
-        private static Rect GetAnchorRectangle(TopLevel topLevel, Visual target, Rect? rect)
-        {
-            if (target == null)
-                throw new InvalidOperationException("Placement mode is not Pointer and PlacementTarget is null");
-            var matrix = target.TransformToVisual(topLevel);
-            if (matrix == null)
-            {
-                if (target.GetVisualRoot() == null)
-                    throw new InvalidOperationException("Target control is not attached to the visual tree");
-                throw new InvalidOperationException("Target control is not in the same tree as the popup parent");
-            }
-
-            var bounds = new Rect(default, target.Bounds.Size);
-            var anchorRect = rect ?? bounds;
-            return anchorRect.Intersect(bounds).TransformToAABB(matrix.Value);
-        }
     }
 
 }