GeekDesk/Util/MouseUtilities.cs

using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Media;

namespace WPF.JoshSmith.Controls.Utilities
{
    /// <summary>
    /// Provides access to the mouse location by calling unmanaged code.
    /// </summary>
    /// <remarks>
    /// This class was written by Dan Crevier (Microsoft).  
    /// http://blogs.msdn.com/llobo/archive/2006/09/06/Scrolling-Scrollviewer-on-Mouse-Drag-at-the-boundaries.aspx
    /// </remarks>
    public class MouseUtilities
    {
        [StructLayout(LayoutKind.Sequential)]
        private struct Win32Point
        {
            public Int32 X;
            public Int32 Y;
        };

        [DllImport("user32.dll")]
        private static extern bool GetCursorPos(ref Win32Point pt);

        [DllImport("user32.dll")]
        private static extern bool ScreenToClient(IntPtr hwnd, ref Win32Point pt);

        /// <summary>
        /// Returns the mouse cursor location.  This method is necessary during 
        /// a drag-drop operation because the WPF mechanisms for retrieving the
        /// cursor coordinates are unreliable.
        /// </summary>
        /// <param name="relativeTo">The Visual to which the mouse coordinates will be relative.</param>
        public static Point GetMousePosition(Visual relativeTo)
        {
            Win32Point mouse = new Win32Point();
            GetCursorPos(ref mouse);

            // Using PointFromScreen instead of Dan Crevier's code (commented out below)
            // is a bug fix created by William J. Roberts.  Read his comments about the fix
            // here: http://www.codeproject.com/useritems/ListViewDragDropManager.asp?msg=1911611#xx1911611xx
            return relativeTo.PointFromScreen(new Point((double)mouse.X, (double)mouse.Y));

            #region Commented Out
            //System.Windows.Interop.HwndSource presentationSource =
            //    (System.Windows.Interop.HwndSource)PresentationSource.FromVisual( relativeTo );
            //ScreenToClient( presentationSource.Handle, ref mouse );
            //GeneralTransform transform = relativeTo.TransformToAncestor( presentationSource.RootVisual );
            //Point offset = transform.Transform( new Point( 0, 0 ) );
            //return new Point( mouse.X - offset.X, mouse.Y - offset.Y );
            #endregion // Commented Out
        }
    }
}