community/InkCanvasForClass/Helpers/IsOutsideOfScreenHelper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Interop;
using System.Windows;

namespace Ink_Canvas.Helpers {
    internal class IsOutsideOfScreenHelper {
        public static bool IsOutsideOfScreen(FrameworkElement target) {
            var hwndSource = (HwndSource)PresentationSource.FromVisual(target);
            if (hwndSource is null) {
                return true;
            }

            var hWnd = hwndSource.Handle;
            var targetBounds = GetPixelBoundsToScreen(target);

            var screens = System.Windows.Forms.Screen.AllScreens;
            return !screens.Any(x => x.Bounds.IntersectsWith(targetBounds));

            System.Drawing.Rectangle GetPixelBoundsToScreen(FrameworkElement visual) {
                var pixelBoundsToScreen = Rect.Empty;
                pixelBoundsToScreen.Union(visual.PointToScreen(new Point(0, 0)));
                pixelBoundsToScreen.Union(visual.PointToScreen(new Point(visual.ActualWidth, 0)));
                pixelBoundsToScreen.Union(visual.PointToScreen(new Point(0, visual.ActualHeight)));
                pixelBoundsToScreen.Union(visual.PointToScreen(new Point(visual.ActualWidth, visual.ActualHeight)));
                return new System.Drawing.Rectangle(
                    (int)pixelBoundsToScreen.X, (int)pixelBoundsToScreen.Y,
                    (int)pixelBoundsToScreen.Width, (int)pixelBoundsToScreen.Height);
            }
        }
    }
}