[DYN-7840] Inaccurate popup placement for input nodes in collapsed groups - Follow-up (#16263)

Author: ivaylo-matov

src/DynamoCoreWpf/Controls/InPortContextMenu.xaml

@@ -139,13 +139,13 @@
         <Path Grid.Column="1"
               HorizontalAlignment="Right"
               VerticalAlignment="Center"
-              Data="M 12,10 L -1,5 -1,15 Z"
+              Data="M 12,6 L -1,1 -1,11 Z"
               Fill="White"
               Stroke="#999999" />
         <Path Grid.Column="0"
               HorizontalAlignment="Right"
               VerticalAlignment="Center"
-              Data="M 2,5 0,5 L0,10 L2,10 Z"
+              Data="M 2,1 0,1 L0,6 L2,6 Z"
               Stretch="None"
               Fill="White"
               Stroke="White" />

src/DynamoCoreWpf/ViewModels/Core/PortViewModel.cs

@@ -375,18 +375,20 @@ internal void SetupPortContextMenuPlacement(Popup popup)
         /// </summary>
         private void ConfigurePopupPlacement(Popup popup, double zoom)
         {
+            var dpiScale = GetDpiScale();
+
             popup.CustomPopupPlacementCallback = (popupSize, targetSize, offset) =>
             {
                 double x;
                 double y = (targetSize.Height - popupSize.Height) / 2;
 
                 if (this is InPortViewModel)
                 {
-                    x = -popupSize.Width + proxyPortContextMenuOffset * zoom;                    
+                    x = -popupSize.Width + proxyPortContextMenuOffset * zoom * dpiScale;                    
                 }
                 else
                 {
-                    x = targetSize.Width - proxyPortContextMenuOffset * zoom;
+                    x = targetSize.Width - proxyPortContextMenuOffset * zoom * dpiScale;
                 }
 
                 return new[] { new CustomPopupPlacement(new Point(x, y), PopupPrimaryAxis.None) };
@@ -398,6 +400,7 @@ private CustomPopupPlacement[] PlacePortContextMenu(Size popupSize, Size targetS
             // The actual zoom here is confusing
             // What matters is the zoom factor measured from the scaled : unscaled node size
             var zoom = node.WorkspaceViewModel.Zoom;
+            var dpiScale = GetDpiScale();
 
             double x;
             var scaledWidth = autocompletePopupSpacing * targetSize.Width / node.ActualWidth;
@@ -421,13 +424,31 @@ private CustomPopupPlacement[] PlacePortContextMenu(Size popupSize, Size targetS
             var rowOffset = PortModel.Index * PortModel.Height * zoom;
             var customNodeOffset = NodeModel.CustomNodeTopBorderHeight * zoom;
 
-            var y = popupHeightOffset + headerHeightOffset + portHalfHeight + rowOffset + customNodeOffset;
+            // popupSize.Height is already DPI-scaled (in screen pixels), so we do NOT apply dpiScale to it
+            // All other layout values are in logical units and must be multiplied by dpiScale for correct placement
+            var y = popupHeightOffset + (headerHeightOffset + portHalfHeight + rowOffset + customNodeOffset) * dpiScale;
 
             var placement = new CustomPopupPlacement(new Point(x, y), PopupPrimaryAxis.None);
 
             return new[] { placement };
         }
 
+        private static double GetDpiScale()
+        {
+            double dpiScale = 1.0;
+            try
+            {
+                var source = PresentationSource.FromVisual(Application.Current.MainWindow);
+                dpiScale = source?.CompositionTarget?.TransformToDevice.M22 ?? 1.0;
+            }
+            catch
+            {
+                // fallback to default DPI scale of 1.0 if anything fails
+            }
+
+            return dpiScale;
+        }
+
         private void WorkspacePropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
         {
             switch (e.PropertyName)