在 WPF 中将窗口置于最前面

Question

How can I bring my WPF application to the front of the desktop? So far I've tried:

SwitchToThisWindow(new WindowInteropHelper(Application.Current.MainWindow).Handle, true);

SetWindowPos(new WindowInteropHelper(Application.Current.MainWindow).Handle, IntPtr.Zero, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);

SetForegroundWindow(new WindowInteropHelper(Application.Current.MainWindow).Handle);

None of which are doing the job ( Marshal.GetLastWin32Error() is saying these operations completed successfully, and the P/Invoke attributes for each definition do have SetLastError=true ).

If I create a new blank WPF application, and call SwitchToThisWindow with a timer, it works exactly as expected, so I'm not sure why it's not working in my original case.

Edit : I'm doing this in conjunction with a global hotkey.

Answer 1

myWindow.Activate();

Attempts to bring the window to the foreground and activates it.

That should do the trick, unless I misunderstood and you want Always on Top behavior. In that case you want:

myWindow.TopMost = true;

Answer 2

I have found a solution that brings the window to the top, but it behaves as a normal window:

if (!Window.IsVisible)
{
    Window.Show();
}

if (Window.WindowState == WindowState.Minimized)
{
    Window.WindowState = WindowState.Normal;
}

Window.Activate();
Window.Topmost = true;  // important
Window.Topmost = false; // important
Window.Focus();         // important

Answer 3

In case you need the window to be in front the first time it loads then you should use the following:

private void Window_ContentRendered(object sender, EventArgs e)
{
    this.Topmost = false;
}

private void Window_Initialized(object sender, EventArgs e)
{
    this.Topmost = true;
}

Or by overriding the methods:

protected override void OnContentRendered(EventArgs e)
{
    base.OnContentRendered(e);
    Topmost = false;
}

protected override void OnInitialized(EventArgs e)
{
    base.OnInitialized(e);
    Topmost = true;
}

Answer 4

I know this question is rather old, but I've just come across this precise scenario and wanted to share the solution I've implemented.

As mentioned in comments on this page, several of the solutions proposed do not work on XP, which I need to support in my scenario. While I agree with the sentiment by @Matthew Xavier that generally this is a bad UX practice, there are times where it's entirely a plausable UX.

The solution to bringing a WPF window to the top was actually provided to me by the same code I'm using to provide the global hotkey. A blog article by Joseph Cooney contains a link to his code samples that contains the original code.

I've cleaned up and modified the code a little, and implemented it as an extension method to System.Windows.Window. I've tested this on XP 32 bit and Win7 64 bit, both of which work correctly.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Interop;
using System.Runtime.InteropServices;

namespace System.Windows
{
    public static class SystemWindows
    {
        #region Constants

        const UInt32 SWP_NOSIZE = 0x0001;
        const UInt32 SWP_NOMOVE = 0x0002;
        const UInt32 SWP_SHOWWINDOW = 0x0040;

        #endregion

        /// <summary>
        /// Activate a window from anywhere by attaching to the foreground window
        /// </summary>
        public static void GlobalActivate(this Window w)
        {
            //Get the process ID for this window's thread
            var interopHelper = new WindowInteropHelper(w);
            var thisWindowThreadId = GetWindowThreadProcessId(interopHelper.Handle, IntPtr.Zero);

            //Get the process ID for the foreground window's thread
            var currentForegroundWindow = GetForegroundWindow();
            var currentForegroundWindowThreadId = GetWindowThreadProcessId(currentForegroundWindow, IntPtr.Zero);

            //Attach this window's thread to the current window's thread
            AttachThreadInput(currentForegroundWindowThreadId, thisWindowThreadId, true);

            //Set the window position
            SetWindowPos(interopHelper.Handle, new IntPtr(0), 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_SHOWWINDOW);

            //Detach this window's thread from the current window's thread
            AttachThreadInput(currentForegroundWindowThreadId, thisWindowThreadId, false);

            //Show and activate the window
            if (w.WindowState == WindowState.Minimized) w.WindowState = WindowState.Normal;
            w.Show();
            w.Activate();
        }

        #region Imports

        [DllImport("user32.dll")]
        private static extern IntPtr GetForegroundWindow();

        [DllImport("user32.dll")]
        private static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr ProcessId);

        [DllImport("user32.dll")]
        private static extern bool AttachThreadInput(uint idAttach, uint idAttachTo, bool fAttach);

        [DllImport("user32.dll")]
        public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);

        #endregion
    }
}

I hope this code helps others who encounter this problem.

Answer 5

To make this a quick copy-paste one -
Use this class' DoOnProcess method to move process' main window to foreground (but not to steal focus from other windows)

public class MoveToForeground
{
    [DllImportAttribute("User32.dll")]
    private static extern int FindWindow(String ClassName, String WindowName);

    const int SWP_NOMOVE        = 0x0002;
    const int SWP_NOSIZE        = 0x0001;            
    const int SWP_SHOWWINDOW    = 0x0040;
    const int SWP_NOACTIVATE    = 0x0010;
    [DllImport("user32.dll", EntryPoint = "SetWindowPos")]
    public static extern IntPtr SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int Y, int cx, int cy, int wFlags);

    public static void DoOnProcess(string processName)
    {
        var allProcs = Process.GetProcessesByName(processName);
        if (allProcs.Length > 0)
        {
            Process proc = allProcs[0];
            int hWnd = FindWindow(null, proc.MainWindowTitle.ToString());
            // Change behavior by settings the wFlags params. See http://msdn.microsoft.com/en-us/library/ms633545(VS.85).aspx
            SetWindowPos(new IntPtr(hWnd), 0, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW | SWP_NOACTIVATE);
        }
    }
}

HTH

Answer 6

If the user is interacting with another application, it may not be possible to bring yours to the front. As a general rule, a process can only expect to set the foreground window if that process is already the foreground process. (Microsoft documents the restrictions in the SetForegroundWindow() MSDN entry.) This is because:

1. The user "owns" the foreground. For example, it would be extremely annoying if another program stole the foreground while the user is typing, at the very least interrupting her workflow, and possibly causing unintended consequences as her keystrokes meant for one application are misinterpreted by the offender until she notices the change.
2. Imagine that each of two programs checks to see if its window is the foreground and attempts to set it to the foreground if it is not. As soon as the second program is running, the computer is rendered useless as the foreground bounces between the two at every task switch.

Answer 7

Why some of the answers on this page are wrong!

• Any answer that uses window.Focus() is wrong.

  • Why? If a notification message pops up, window.Focus() will grab the focus away from whatever the user is typing at the time. This is insanely frustrating for end users, especially if the popups occur quite frequently.

• Any answer that uses window.Activate() is wrong.

  • Why? It will make any parent windows visible as well.
• Any answer that omits window.ShowActivated = false is wrong.
  • Why? It will grab the focus away from another window when the message pops up which is very annoying!
• Any answer that does not use Visibility.Visible to hide/show the window is wrong.
  • Why? If we are using Citrix, if the window is not collapsed when it is closed, it will leave a weird black rectangular hold on the screen. Thus, we cannot use window.Show() and window.Hide() .

Essentially:

• The window should not grab the focus away from any other window when it activates;
• The window should not activate its parent when it is shown;
• The window should be compatible with Citrix.

MVVM Solution

This code is 100% compatible with Citrix (no blank areas of the screen). It is tested with both normal WPF and DevExpress.

This answer is intended for any use case where we want a small notification window that is always in front of other windows (if the user selects this in the preferences).

If this answer seems more complex than the others, it's because it is robust, enterprise level code. Some of the other answers on this page are simple, but do not actually work.

XAML - Attached Property

Add this attached property to any UserControl within the window. The attached property will:

• Wait until the Loaded event is fired (otherwise it cannot look up the visual tree to find the parent window).
• Add an event handler that ensures that the window is visible or not.

At any point, you can set the window to be in front or not, by flipping the value of the attached property.

<UserControl x:Class="..."
         ...
         attachedProperties:EnsureWindowInForeground.EnsureWindowInForeground=
             "{Binding EnsureWindowInForeground, Mode=OneWay}">

C# - Helper Method

public static class HideAndShowWindowHelper
{
    /// <summary>
    ///     Intent: Ensure that small notification window is on top of other windows.
    /// </summary>
    /// <param name="window"></param>
    public static void ShiftWindowIntoForeground(Window window)
    {
        try
        {
            // Prevent the window from grabbing focus away from other windows the first time is created.
            window.ShowActivated = false;

            // Do not use .Show() and .Hide() - not compatible with Citrix!
            if (window.Visibility != Visibility.Visible)
            {
                window.Visibility = Visibility.Visible;
            }

            // We can't allow the window to be maximized, as there is no de-maximize button!
            if (window.WindowState == WindowState.Maximized)
            {
                window.WindowState = WindowState.Normal;
            }

            window.Topmost = true;
        }
        catch (Exception)
        {
            // Gulp. Avoids "Cannot set visibility while window is closing".
        }
    }

    /// <summary>
    ///     Intent: Ensure that small notification window can be hidden by other windows.
    /// </summary>
    /// <param name="window"></param>
    public static void ShiftWindowIntoBackground(Window window)
    {
        try
        {
            // Prevent the window from grabbing focus away from other windows the first time is created.
            window.ShowActivated = false;

            // Do not use .Show() and .Hide() - not compatible with Citrix!
            if (window.Visibility != Visibility.Collapsed)
            {
                window.Visibility = Visibility.Collapsed;
            }

            // We can't allow the window to be maximized, as there is no de-maximize button!
            if (window.WindowState == WindowState.Maximized)
            {
                window.WindowState = WindowState.Normal;
            }

            window.Topmost = false;
        }
        catch (Exception)
        {
            // Gulp. Avoids "Cannot set visibility while window is closing".
        }
    }
}

Usage

In order to use this, you need to create the window in your ViewModel:

private ToastView _toastViewWindow;
private void ShowWindow()
{
    if (_toastViewWindow == null)
    {
        _toastViewWindow = new ToastView();
        _dialogService.Show<ToastView>(this, this, _toastViewWindow, true);
    }
    ShiftWindowOntoScreenHelper.ShiftWindowOntoScreen(_toastViewWindow);
    HideAndShowWindowHelper.ShiftWindowIntoForeground(_toastViewWindow);
}

private void HideWindow()
{
    if (_toastViewWindow != null)
    {
        HideAndShowWindowHelper.ShiftWindowIntoBackground(_toastViewWindow);
    }
}

Additional links

For tips on how ensure that a notification window always shifts back onto the visible screen, see my answer: In WPF, how to shift a window onto the screen if it is off the screen? .

Answer 8

I know that this is late answer, maybe helpful for researchers

 if (!WindowName.IsVisible)
 {
     WindowName.Show();
     WindowName.Activate();
 }

Answer 9

I have had a similar problem with a WPF application that gets invoked from an Access application via the Shell object.

My solution is below - works in XP and Win7 x64 with app compiled to x86 target.

I'd much rather do this than simulate an alt-tab.

void Window_Loaded(object sender, RoutedEventArgs e)
{
    // make sure the window is normal or maximised
    // this was the core of the problem for me;
    // even though the default was "Normal", starting it via shell minimised it
    this.WindowState = WindowState.Normal;

    // only required for some scenarios
    this.Activate();
}

Answer 10

Well, since this is such a hot topic... here is what works for me. I got errors if I didn't do it this way because Activate() will error out on you if you cannot see the window.

Xaml:

<Window .... 
        Topmost="True" 
        .... 
        ContentRendered="mainWindow_ContentRendered"> .... </Window>

Codebehind:

private void mainWindow_ContentRendered(object sender, EventArgs e)
{
    this.Topmost = false;
    this.Activate();
    _UsernameTextBox.Focus();
}

This was the only way for me to get the window to show on top. Then activate it so you can type in the box without having to set focus with the mouse. control.Focus() wont work unless the window is Active();

Answer 11

Well I figured out a work around. I'm making the call from a keyboard hook used to implement a hotkey. The call works as expected if I put it into a BackgroundWorker with a pause. It's a kludge, but I have no idea why it wasn't working originally.

void hotkey_execute()
{
    IntPtr handle = new WindowInteropHelper(Application.Current.MainWindow).Handle;
    BackgroundWorker bg = new BackgroundWorker();
    bg.DoWork += new DoWorkEventHandler(delegate
        {
            Thread.Sleep(10);
            SwitchToThisWindow(handle, true);
        });
    bg.RunWorkerAsync();
}

Answer 12

To show ANY currently opened window import those DLL:

public partial class Form1 : Form
{
    [DllImportAttribute("User32.dll")]
    private static extern int FindWindow(String ClassName, String WindowName);
    [DllImportAttribute("User32.dll")]
    private static extern int SetForegroundWindow(int hWnd);

and in program We search for app with specified title (write title without first letter (index > 0))

  foreach (Process proc in Process.GetProcesses())
                {
                    tx = proc.MainWindowTitle.ToString();
                    if (tx.IndexOf("Title of Your app WITHOUT FIRST LETTER") > 0)
                    {
                        tx = proc.MainWindowTitle;
                        hWnd = proc.Handle.ToInt32(); break;
                    }
                }
                hWnd = FindWindow(null, tx);
                if (hWnd > 0)
                {
                    SetForegroundWindow(hWnd);
                }

Answer 13

These codes will work fine all times.

At first set the activated event handler in XAML:

Activated="Window_Activated"

Add below line to your Main Window constructor block:

public MainWindow()
{
    InitializeComponent();
    this.LocationChanged += (sender, e) => this.Window_Activated(sender, e);
}

And inside the activated event handler copy this codes:

private void Window_Activated(object sender, EventArgs e)
{
    if (Application.Current.Windows.Count > 1)
    {
        foreach (Window win in Application.Current.Windows)
            try
            {
                if (!win.Equals(this))
                {
                    if (!win.IsVisible)
                    {
                        win.ShowDialog();
                    }

                    if (win.WindowState == WindowState.Minimized)
                    {
                        win.WindowState = WindowState.Normal;
                    }

                    win.Activate();
                    win.Topmost = true;
                    win.Topmost = false;
                    win.Focus();
                }
            }
            catch { }
    }
    else
        this.Focus();
}

These steps will works fine and will bring to front all other windows into their parents window.

Answer 14

Just wanted to add another solution to this question. This implementation works for my scenario, where CaliBurn is responsible for displaying the main Window.

protected override void OnStartup(object sender, StartupEventArgs e)
{
    DisplayRootViewFor<IMainWindowViewModel>();

    Application.MainWindow.Topmost = true;
    Application.MainWindow.Activate();
    Application.MainWindow.Activated += OnMainWindowActivated;
}

private static void OnMainWindowActivated(object sender, EventArgs e)
{
    var window = sender as Window;
    if (window != null)
    {
        window.Activated -= OnMainWindowActivated;
        window.Topmost = false;
        window.Focus();
    }
}

Answer 15

The problem could be that the thread calling your code from the hook hasn't been initialized by the runtime so calling runtime methods don't work.

Perhaps you could try doing an Invoke to marshal your code on to the UI thread to call your code that brings the window to the foreground.

Answer 16

If you are trying to hide the window, for example you minimize the window, I have found that using

    this.Hide();

will hide it correctly, then simply using

    this.Show();

will then show the window as the top most item once again.

Answer 17

Remember not to put the code that shows that window inside a PreviewMouseDoubleClick handler as the active window will switch back to the window who handled the event. Just put it in the MouseDoubleClick event handler or stop bubbling by setting e.Handled to True.

In my case i was handling the PreviewMouseDoubleClick on a Listview and was not setting the e.Handled = true then it raised the MouseDoubleClick event witch sat focus back to the original window.

Answer 18

This is a combination of a few suggestions above that works well and is simple. It only comes to front when those events fire, so any window that pops up after the event will stay on top of course.

public partial class MainWindow : Window
{
    protected override void OnContentRendered(EventArgs e)
    {
        base.OnContentRendered(e);

        Topmost = true;
        Topmost = false;
    }
    protected override void OnInitialized(EventArgs e)
    {
        base.OnInitialized(e);

        Topmost = true;
        Topmost = false;
    }

    ....
}

Answer 19

I built an extension method to make for easy reuse.

using System.Windows.Forms;
    namespace YourNamespace{
        public static class WindowsFormExtensions {
            public static void PutOnTop(this Form form) {
                form.Show();
                form.Activate();
            }// END PutOnTop()       
        }// END class
    }// END namespace

Call in the Form Constructor

namespace YourNamespace{
       public partial class FormName : Form {
       public FormName(){
            this.PutOnTop();
            InitalizeComponents();
        }// END Constructor
    } // END Form            
}// END namespace