Retrieve a window handle (HWND)

Article
2024-08-28

This topic shows you how, in a desktop app, to retrieve the window handle for a window. The scope covers WinUI 3, Windows Presentation Foundation (WPF), and Windows Forms (WinForms) apps; code examples are presented in C# and C++/WinRT.

The development and UI frameworks listed above are (behind the scenes) built on the Win32 API. In Win32, a window object is identified by a value known as a window handle. And the type of a window handle is an HWND (although it surfaces in C# as an IntPtr). In any case, you'll hear the term HWND used as a shorthand for window handle.

There are several reasons to retrieve the HWND for a window in your WinUI 3, WPF, or WinForms desktop app. One example is to use the HWND to interoperate with certain Windows Runtime (WinRT) objects that depend on a CoreWindow to display a user-interface (UI). For more info, see Display WinRT UI objects that depend on CoreWindow.

WinUI 3 with C#

The C# code below shows how to retrieve the window handle (HWND) for a WinUI 3 Window object. This example calls the GetWindowHandle method on the WinRT.Interop.WindowNative C# interop class. For more info about the C# interop classes, see Call interop APIs from a .NET app.

// MainWindow.xaml.cs
private async void myButton_Click(object sender, RoutedEventArgs e)
{
    // Retrieve the window handle (HWND) of the current WinUI 3 window.
    var hWnd = WinRT.Interop.WindowNative.GetWindowHandle(this);
}

WinUI 3 with C++

The C++/WinRT code below shows how to retrieve the window handle (HWND) for a WinUI 3 Window object. This example calls the IWindowNative::get_WindowHandle method.

// pch.h
...
#include <microsoft.ui.xaml.window.h>

// MainWindow.xaml.cpp
void MainWindow::myButton_Click(IInspectable const&, RoutedEventArgs const&)
{
    // Retrieve the window handle (HWND) of the current WinUI 3 window.
    auto windowNative{ this->m_inner.as<::IWindowNative>() };
    HWND hWnd{ 0 };
    windowNative->get_WindowHandle(&hWnd);
}

WPF with C#

The C# code below shows how to retrieve the window handle (HWND) for a WPF window object. This example uses the WindowInteropHelper class.

// MainWindow.xaml.cs
private void Button_Click(object sender, RoutedEventArgs e)
{
    var wih = new System.Windows.Interop.WindowInteropHelper(this);
    var hWnd = wih.Handle;
}

WinForms with C#

The C# code below shows how to retrieve the window handle (HWND) for a WinForms form object. This example uses the NativeWindow.Handle property.

// Form1.cs
private void button1_Click(object sender, EventArgs e)
{
    var hWnd = this.Handle;
}

Determining the window that's hosting a visual element

From a visual element, you can access UIElement.XamlRoot; then XamlRoot.ContentIslandEnvironment; then the ContentIslandEnvironment.AppWindowId property contains the ID of the top-level Win32 HWND.

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