Boogaart.Silverlight.Behaviors.Popup.TryPlacePopup C# (CSharp) Method

        private static bool TryPlacePopup(Windows.Popup popup, FrameworkElement parent, FrameworkElement placementParent, FrameworkElement placementChild, PopupOrientation orientation)
        {
            var availableWidth = placementParent.ActualWidth;
            var availableHeight = placementParent.ActualHeight;

            SetActualOrientation(popup, orientation);
            placementChild.Measure(new Size(availableWidth, availableHeight));

            var requiredWidth = placementChild.DesiredSize.Width;
            var requiredHeight = placementChild.DesiredSize.Height;
            var placementTarget = GetPlacementTarget(popup) ?? parent;
            var parentTransform = placementTarget.TransformToVisual(parent);
            var popupLocation = parentTransform.Transform(new Point(0, 0));

            switch (orientation.Placement)
            {
                case PopupPlacement.Top:
                    popupLocation.Y -= requiredHeight;
                    break;
                case PopupPlacement.Bottom:
                    popupLocation.Y += placementTarget.ActualHeight;
                    break;
                case PopupPlacement.Left:
                    popupLocation.X -= requiredWidth;
                    break;
                case PopupPlacement.Right:
                    popupLocation.X += placementTarget.ActualWidth;
                    break;
            }

            if (orientation.Placement == PopupPlacement.Top || orientation.Placement == PopupPlacement.Bottom)
            {
                switch (orientation.HorizontalAlignment)
                {
                    case PopupHorizontalAlignment.RightCenter:
                        popupLocation.X += ((placementTarget.ActualWidth / 2) - requiredWidth);
                        break;
                    case PopupHorizontalAlignment.Center:
                        popupLocation.X += ((placementTarget.ActualWidth - requiredWidth) / 2);
                        break;
                    case PopupHorizontalAlignment.LeftCenter:
                        popupLocation.X += (placementTarget.ActualWidth / 2);
                        break;
                    case PopupHorizontalAlignment.Right:
                        popupLocation.X += (placementTarget.ActualWidth - requiredWidth);
                        break;
                }
            }

            if (orientation.Placement == PopupPlacement.Left || orientation.Placement == PopupPlacement.Right)
            {
                switch (orientation.VerticalAlignment)
                {
                    case PopupVerticalAlignment.BottomCenter:
                        popupLocation.Y += ((placementTarget.ActualHeight / 2) - requiredHeight);
                        break;
                    case PopupVerticalAlignment.Center:
                        popupLocation.Y += ((placementTarget.ActualHeight - requiredHeight) / 2);
                        break;
                    case PopupVerticalAlignment.TopCenter:
                        popupLocation.Y += (placementTarget.ActualHeight / 2);
                        break;
                    case PopupVerticalAlignment.Bottom:
                        popupLocation.Y += (placementTarget.ActualHeight - requiredHeight);
                        break;
                }
            }

            var popupLocationRelativeToPlacementParent = popupLocation;

            if (parent != placementParent)
            {
                var placementParentTransform = placementTarget.TransformToVisual(placementParent);
                popupLocationRelativeToPlacementParent = placementParentTransform.Transform(popupLocation);
            }

            if (popupLocationRelativeToPlacementParent.X < 0
                || popupLocationRelativeToPlacementParent.Y < 0
                || (popupLocationRelativeToPlacementParent.X + requiredWidth) > availableWidth
                || (popupLocationRelativeToPlacementParent.Y + requiredHeight) > availableHeight)
            {
                // not enough room
                return false;
            }

            popup.HorizontalOffset = popupLocation.X;
            popup.VerticalOffset = popupLocation.Y;

            return true;
        }