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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.
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?
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