wpf-notifyicon/Source/NotifyIconWpf/Interop/TrayInfo.cs

// Some interop code taken from Mike Marshall's AnyForm

using System;
using System.Drawing;
using System.Runtime.InteropServices;


namespace Hardcodet.Wpf.TaskbarNotification.Interop
{
  /// <summary>
  /// Resolves the current tray position.
  /// </summary>
  public static class TrayInfo
  {
    /// <summary>
    /// Gets the position of the system tray.
    /// </summary>
    /// <returns>Tray coordinates.</returns>
    public static Point GetTrayLocation()
    {
      var info = new AppBarInfo();
      info.GetSystemTaskBarPosition();

      Rectangle rcWorkArea = info.WorkArea;

      int x = 0, y = 0;
      if (info.Edge == AppBarInfo.ScreenEdge.Left)
      {
        x = rcWorkArea.Left + 2;
        y = rcWorkArea.Bottom;
      }
      else if (info.Edge == AppBarInfo.ScreenEdge.Bottom)
      {
        x = rcWorkArea.Right;
        y = rcWorkArea.Bottom;
      }
      else if (info.Edge == AppBarInfo.ScreenEdge.Top)
      {
        x = rcWorkArea.Right;
        y = rcWorkArea.Top;
      }
      else if (info.Edge == AppBarInfo.ScreenEdge.Right)
      {
        x = rcWorkArea.Right;
        y = rcWorkArea.Bottom;
      }

      return new Point { X = x, Y = y};
    }
  }




  internal class AppBarInfo
  {

    [DllImport("user32.dll")]
    private static extern IntPtr FindWindow(String lpClassName, String lpWindowName);

    [DllImport("shell32.dll")]
    private static extern UInt32 SHAppBarMessage(UInt32 dwMessage, ref APPBARDATA data);

    [DllImport("user32.dll")]
    private static extern Int32 SystemParametersInfo(UInt32 uiAction, UInt32 uiParam,
                                                     IntPtr pvParam, UInt32 fWinIni);


    private const int ABE_BOTTOM = 3;
    private const int ABE_LEFT = 0;
    private const int ABE_RIGHT = 2;
    private const int ABE_TOP = 1;

    private const int ABM_GETTASKBARPOS = 0x00000005;

    // SystemParametersInfo constants
    private const UInt32 SPI_GETWORKAREA = 0x0030;

    private APPBARDATA m_data;

    public ScreenEdge Edge
    {
      get { return (ScreenEdge) m_data.uEdge; }
    }


    public Rectangle WorkArea
    {
      get
      {
        Int32 bResult = 0;
        var rc = new RECT();
        IntPtr rawRect = Marshal.AllocHGlobal(Marshal.SizeOf(rc));
        bResult = SystemParametersInfo(SPI_GETWORKAREA, 0, rawRect, 0);
        rc = (RECT) Marshal.PtrToStructure(rawRect, rc.GetType());

        if (bResult == 1)
        {
          Marshal.FreeHGlobal(rawRect);
          return new Rectangle(rc.left, rc.top, rc.right - rc.left, rc.bottom - rc.top);
        }

        return new Rectangle(0, 0, 0, 0);
      }
    }



    public void GetPosition(string strClassName, string strWindowName)
    {
      m_data = new APPBARDATA();
      m_data.cbSize = (UInt32) Marshal.SizeOf(m_data.GetType());

      IntPtr hWnd = FindWindow(strClassName, strWindowName);

      if (hWnd != IntPtr.Zero)
      {
        UInt32 uResult = SHAppBarMessage(ABM_GETTASKBARPOS, ref m_data);

        if (uResult != 1)
        {
          throw new Exception("Failed to communicate with the given AppBar");
        }
      }
      else
      {
        throw new Exception("Failed to find an AppBar that matched the given criteria");
      }
    }


    public void GetSystemTaskBarPosition()
    {
      GetPosition("Shell_TrayWnd", null);
    }




    public enum ScreenEdge
    {
      Undefined = -1,
      Left = ABE_LEFT,
      Top = ABE_TOP,
      Right = ABE_RIGHT,
      Bottom = ABE_BOTTOM
    }


    [StructLayout(LayoutKind.Sequential)]
    private struct APPBARDATA
    {
      public UInt32 cbSize;
      public IntPtr hWnd;
      public UInt32 uCallbackMessage;
      public UInt32 uEdge;
      public RECT rc;
      public Int32 lParam;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct RECT
    {
      public Int32 left;
      public Int32 top;
      public Int32 right;
      public Int32 bottom;
    }

  }
}