internal override Point GetPosition(IInputElement relativeTo) { VerifyAccess(); // Validate that relativeTo is either a UIElement or a ContentElement if (relativeTo != null && !InputElement.IsValid(relativeTo)) { throw new InvalidOperationException(); } PresentationSource relativePresentationSource = null; if (relativeTo != null) { DependencyObject dependencyObject = relativeTo as DependencyObject; DependencyObject containingVisual = InputElement.GetContainingVisual(dependencyObject); if (containingVisual != null) { relativePresentationSource = PresentationSource.CriticalFromVisual(containingVisual); } } else { if (_inputSource != null) { relativePresentationSource = _inputSource.Value; } } // Verify that we have a valid PresentationSource with a valid RootVisual // - if we don't we won't be able to invoke ClientToRoot or TranslatePoint and // we will just return 0,0 if (relativePresentationSource == null || relativePresentationSource.RootVisual == null) { return(new Point(0, 0)); } Point curPoint = new Point(_pointerData.Info.ptPixelLocationRaw.X, _pointerData.Info.ptPixelLocationRaw.Y); Point ptClient = PointUtil.ScreenToClient(curPoint, relativePresentationSource); Point ptRoot = PointUtil.ClientToRoot(ptClient, relativePresentationSource); Point ptRelative = InputElement.TranslatePoint(ptRoot, relativePresentationSource.RootVisual, (DependencyObject)relativeTo); return(ptRelative); }