Saving window size and location in WPF and WinForms

A common user interface tweak is to save the size and location of a window and restore that state when the program starts up again. That way, the users don’t need to re-do their work of resizing and moving the windows to where they want them. However I’ve found that there isn’t really a convenient way to do with in C#. Many solutions focus on recording the window width, height, x and y coordinates and current state (maximized, restored, etc), then applying all those values again on startup. But then you have to deal with edge cases: What if the user has changed resolutions since your program last ran? What if it was present on a monitor that’s now disconnected?

Fortunately, there are a couple of native Windows functions that can do all this work for us: SetWindowPlacement and GetWindowPlacement. MSDN has a sample demonstrating how to PInvoke to these functions in a WPF project, but it’s got a few issues with it. For one, it’s trying to store the placement as a custom type in settings, which can cause strange errors every time you open your Settings file. Here’s my take on it:

 using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using System.Xml;
using System.Xml.Serialization;

namespace WindowPlacementExample
{
    // RECT structure required by WINDOWPLACEMENT structure
    [Serializable]
    [StructLayout(LayoutKind.Sequential)]
    public struct RECT
    {
        public int Left;
        public int Top;
        public int Right;
        public int Bottom;

        public RECT(int left, int top, int right, int bottom)
        {
            this.Left = left;
            this.Top = top;
            this.Right = right;
            this.Bottom = bottom;
        }
    }

    // POINT structure required by WINDOWPLACEMENT structure
    [Serializable]
    [StructLayout(LayoutKind.Sequential)]
    public struct POINT
    {
        public int X;
        public int Y;

        public POINT(int x, int y)
        {
            this.X = x;
            this.Y = y;
        }
    }

    // WINDOWPLACEMENT stores the position, size, and state of a window
    [Serializable]
    [StructLayout(LayoutKind.Sequential)]
    public struct WINDOWPLACEMENT
    {
        public int length;
        public int flags;
        public int showCmd;
        public POINT minPosition;
        public POINT maxPosition;
        public RECT normalPosition;
    }

    public static class WindowPlacement
    {
        private static Encoding encoding = new UTF8Encoding();
        private static XmlSerializer serializer = new XmlSerializer(typeof(WINDOWPLACEMENT));

        [DllImport("user32.dll")]
        private static extern bool SetWindowPlacement(IntPtr hWnd, [In] ref WINDOWPLACEMENT lpwndpl);

        [DllImport("user32.dll")]
        private static extern bool GetWindowPlacement(IntPtr hWnd, out WINDOWPLACEMENT lpwndpl);

        private const int SW_SHOWNORMAL = 1;
        private const int SW_SHOWMINIMIZED = 2;

        public static void SetPlacement(IntPtr windowHandle, string placementXml)
        {
            if (string.IsNullOrEmpty(placementXml))
            {
                return;
            }

            WINDOWPLACEMENT placement;
            byte[] xmlBytes = encoding.GetBytes(placementXml);

            try
            {
                using (MemoryStream memoryStream = new MemoryStream(xmlBytes))
                {
                    placement = (WINDOWPLACEMENT)serializer.Deserialize(memoryStream);
                }

                placement.length = Marshal.SizeOf(typeof(WINDOWPLACEMENT));
                placement.flags = 0;
                placement.showCmd = (placement.showCmd == SW_SHOWMINIMIZED ? SW_SHOWNORMAL : placement.showCmd);
                SetWindowPlacement(windowHandle, ref placement);
            }
            catch (InvalidOperationException)
            {
                // Parsing placement XML failed. Fail silently.
            }
        }

        public static string GetPlacement(IntPtr windowHandle)
        {
            WINDOWPLACEMENT placement = new WINDOWPLACEMENT();
            GetWindowPlacement(windowHandle, out placement);

            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.UTF8))
                {
                    serializer.Serialize(xmlTextWriter, placement);
                    byte[] xmlBytes = memoryStream.ToArray();
                    return encoding.GetString(xmlBytes);
                }
            }
        }
    }
}

To get the placement of an existing window, you give it the native handle for the window, and get back a string of XML that represents the placement for the window. You save this string somewhere, then when the program starts back up again, apply it with SetPlacement. The above code works for both WinForms and WPF. And in both cases you can open your Properties/Settings.settings file and add a new setting to store the string:

This will store the window state locally, per-user. Of course you could also store the string wherever you wanted to.

What I like about this approach is that the WindowPlacement class does the XML serialization for you and gives you a nice, tidy string containing all the placement data.

But where in the program code should we hook in to save and re-apply the window placements? The answer is a bit different between WinForms and WPF.

WPF:

You might benefit by throwing a couple of extension methods on the WindowPlacement class to make things a bit easier:

 public static void SetPlacement(this Window window, string placementXml)
{
    WindowPlacement.SetPlacement(new WindowInteropHelper(window).Handle, placementXml);
}

public static string GetPlacement(this Window window)
{
    return WindowPlacement.GetPlacement(new WindowInteropHelper(window).Handle);
}

To save the window placement, just handle the Closing event on the Window:

 private void Window_Closing(object sender, CancelEventArgs e)
{
    Settings.Default.MainWindowPlacement = this.GetPlacement();
    Settings.Default.Save();
}

To restore, you’ll need to hook in on SourceInitialized:

 protected override void OnSourceInitialized(EventArgs e)
{
    base.OnSourceInitialized(e);
    this.SetPlacement(Settings.Default.MainWindowPlacement);
}

WinForms:

This one is a bit more straightforward. Save on the FormClosing event and restore the window state in the Load event handler. The Form’s native handle is accessible from its Handle property.

Now we have a robust and relatively painless way of persisting window sizes and positions, and we only need to keep track of one string per window.

Comments

• Anonymous
  May 25, 2010
  Please can someone for once write this for VB.net and wpf not all of us  code in C

• Anonymous
  August 10, 2010
  The comment has been removed

• Anonymous
  August 11, 2010
  I ended up NOT using UTF-8 encoding (human readability wasn't a factor for me).  UTF-8 has a BOM (Byte Order Marker) that wasn't being encoded/decoded correctly when I saved my string out to the db.  I ended up using Convert.ToBase64String and Convert.FromBase64String. Otherwise it works great!  Thanks!

• Anonymous
  December 21, 2010
  Thanks for the Article - It made the task easy. I was also saving to a DB (SQL 2K - uggh) and I just changed the encoding to ASCII since I still wanted to be able to read the saved xml. Changed lines: private static Encoding encoding = new ASCIIEncoding(); using (XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.ASCII))

• Anonymous
  January 22, 2011
  Looks like REALLY useful code, but it's all cut off on the right side...

• Anonymous
  January 25, 2011
  Yeah they changed the blog formatting on me. I just switched up the layout so you should be able to see everything now. (though you can always copy/paste and get everything anyway)

• Anonymous
  April 12, 2011
  Very nice solution for this. Thanks.

• Anonymous
  October 03, 2011
  Where can I find: Properties/Settings.settings file?

• Anonymous
  October 03, 2011
  BindingFailure was detect in :( private static XmlSerializer serializer = new XmlSerializer(typeof(WINDOWPLACEMENT));

• Anonymous
  November 01, 2011
  @Lordman: It's usually added by default in GUI projects. If you don't have it, you can Add New Item -> Visual C# -> General -> Settings File.

• Anonymous
  July 19, 2012
  Here is my translation to VB.NET: Namespace Extensions    Public Module WindowExtensions #Region "Properties"        Private Property Encoding As System.Text.Encoding = New System.Text.UTF8Encoding()        Private Property Serializer As New System.Xml.Serialization.XmlSerializer(GetType(NativeMethods.WINDOWPLACEMENT)) #End Region #Region "Extension Methods"        <System.Runtime.CompilerServices.Extension> _        Public Sub SetPlacement(window As Window, placementXml As String)            If Not String.IsNullOrEmpty(placementXml) Then                SetPlacement(New System.Windows.Interop.WindowInteropHelper(window).Handle, placementXml)            End If        End Sub        <System.Runtime.CompilerServices.Extension> _        Public Sub SetPlacement(form As System.Windows.Forms.Form, placementXml As String)            If Not String.IsNullOrEmpty(placementXml) Then                SetPlacement(form.Handle, placementXml)            End If        End Sub        <System.Runtime.CompilerServices.Extension> _        Public Function GetPlacement(window As Window) As String            Return GetPlacement(New System.Windows.Interop.WindowInteropHelper(window).Handle)        End Function        <System.Runtime.CompilerServices.Extension> _        Public Function GetPlacement(form As System.Windows.Forms.Form) As String            Return GetPlacement(form.Handle)        End Function #End Region #Region "Supporting Methods"        Private Sub SetPlacement(windowHandle As IntPtr, placementXml As String)            If String.IsNullOrEmpty(placementXml) Then                Return            End If            Dim placement As NativeMethods.WINDOWPLACEMENT            Dim xmlBytes As Byte() = Encoding.GetBytes(placementXml)            Try                Using memoryStream As New System.IO.MemoryStream(xmlBytes)                    placement = DirectCast(Serializer.Deserialize(memoryStream), NativeMethods.WINDOWPLACEMENT)                End Using                placement.length = System.Runtime.InteropServices.Marshal.SizeOf(GetType(NativeMethods.WINDOWPLACEMENT))                placement.flags = 0                placement.showCmd = (If(placement.showCmd = NativeMethods.ShowWindowCommands.ShowMinimized, NativeMethods.ShowWindowCommands.Normal, placement.showCmd))                NativeMethods.SetWindowPlacement(windowHandle, placement)                ' Parsing placement XML failed. Fail silently.            Catch generatedExceptionName As InvalidOperationException            End Try        End Sub        Private Function GetPlacement(windowHandle As IntPtr) As String            Dim placement As New NativeMethods.WINDOWPLACEMENT()            NativeMethods.GetWindowPlacement(windowHandle, placement)            Using memoryStream As New System.IO.MemoryStream                Using xmlTextWriter As New System.Xml.XmlTextWriter(memoryStream, System.Text.Encoding.UTF8)                    Serializer.Serialize(xmlTextWriter, placement)                    Dim xmlBytes As Byte() = memoryStream.ToArray()                    Return Encoding.GetString(xmlBytes)                End Using            End Using        End Function #End Region    End Module End Namespace Namespace Extensions    Public Class NativeMethods        <System.Runtime.InteropServices.DllImport("user32.dll")> _        Public Shared Function SetWindowPlacement(ByVal hWnd As IntPtr, ByRef lpwndpl As WINDOWPLACEMENT) As Boolean        End Function        <System.Runtime.InteropServices.DllImport("user32.dll")> _        Public Shared Function GetWindowPlacement(ByVal hWnd As IntPtr, ByRef lpwndpl As WINDOWPLACEMENT) As Boolean        End Function        ' RECT structure required by WINDOWPLACEMENT structure        <Serializable>        <System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)>        Public Structure RECT            Public Left As Integer            Public Top As Integer            Public Right As Integer            Public Bottom As Integer            Public Sub New(left As Integer, top As Integer, right As Integer, bottom As Integer)                Me.Left = left                Me.Top = top                Me.Right = right                Me.Bottom = bottom            End Sub        End Structure        ' POINT structure required by WINDOWPLACEMENT structure        <Serializable>        <System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)>        Public Structure POINT            Public X As Integer            Public Y As Integer            Public Sub New(x As Integer, y As Integer)                Me.X = x                Me.Y = y            End Sub        End Structure        ' WINDOWPLACEMENT stores the position, size, and state of a window        <Serializable>        <System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)>        Public Structure WINDOWPLACEMENT            Public length As Integer            Public flags As Integer            Public showCmd As ShowWindowCommands            Public minPosition As POINT            Public maxPosition As POINT            Public normalPosition As RECT        End Structure        Public Enum ShowWindowCommands As Integer            Hide = 0            Normal = 1            ShowMinimized = 2            Maximize = 3            ShowMaximized = 3            ShowNoActivate = 4            Show = 5            Minimize = 6            ShowMinNoActive = 7            ShowNA = 8            Restore = 9            ShowDefault = 10            ForceMinimize = 11        End Enum    End Class End Namespace

• Anonymous
  August 24, 2014
  i want to save the window names also what should i do?? I tried but m not getting it

• Anonymous
  August 24, 2014
  please help someone

• Anonymous
  October 29, 2014
  Thanks for the great example, I am implementing it on a c# WPF application. I found a couple of missing items:  In order to keep my code as clean as possible, I put all of this in a new cs file in my application namespace.  I needed to add the following at the top: using System.Windows;//for the Window class using System.WIndows.Interop;//for the Interop helper both of which are for the small extension methods added to the WindowPlacement class just before the code to call the methods in the Window_Close and OnSourceInitialized methods in my main window class. The commands to Set and Get placement refer to "Settings.Default.MainWindowPlacement", which would require a "using Properties;" directive at the top.  I just changed them to "Properties.Settings.Default.MainWindowPlacement"

• Anonymous
  January 02, 2015
  This works great!  I wish I would have found it a long time ago.  Thank you very much.

• Anonymous
  August 19, 2015
  If my window is maximised on the second monitor then close it, when I restart the app the window gets maximised on the primary monitor. Any ideas why?

  • Anonymous
    March 30, 2016
    I also have the same problem? If you found a solution to it please help.