Click here to Skip to main content
13,558,063 members
Click here to Skip to main content
Add your own
alternative version

Tagged as


9 bookmarked
Posted 5 Dec 2010
Licenced CPOL

Win32 Handle (HWND) & WPF Objects - A Note

, 5 Dec 2010
Rate this:
Please Sign up or sign in to vote.
Win32 Handle (HWND) & WPF Objects - A Note

Well, there is a common confusion for many who are working with WPF objects. Is it truly interoperable with Windows environment, or more precisely, does it act the same way as it does with normal Win32 objects?

The problem here comes with the fact that each WPF window has only one window handle (HWND) and each other controls are actually placed as content to the window and does not have any entry on Kernel table(no HWND) except of course Popup class in WPF. In this post, I will try to cover the basis of HWND (for those of you who don't know) and later go on with what are the changes of it with WPF environment.

If you know what HWND is or how it works, please skip the next section.

Overview of Win32 HANDLE

Win32 Handle is very important for any Win32 applications. For every Win32 app, Kernel maintains a Table which has entries to identify a memory address. A HANDLE is actually a DWORD (32 bit integer) which maps the memory address on the table. So if you get a HANDLE, you can easily locate the memory address it points to. Each object that you have in Windows (like windows, buttons, mouse pointers, icon, menu, bitmap, etc.) has entries in the table and the object is traced using both internally by windows or by programs using those HANDLEs. Even though it is just an unsigned integer value, you should not edit the value, otherwise the HANDLE could not be used to point the object anymore.

Based on the Type of HANDLE can be categorized into HWND, HINSTANCE, HMENU.


HWND is a special HANDLE which points to a window object. HWND is said to be a pointer to a Window. To get any Window, its Child or Dialog box object, we need to use an HWND object. Communication between two windows is also done using HWNDs.


HINSTANCE is a special HANDLE which points to a program instance. Kernel keeps a HANDLE to the instance of the program so that later on the program could be communicated from outside.


For every dropdown menu, a HMENU handle will be associated with it. HMENU handle is used to alter content of the dropdown menu item.

WPF Objects and HWND

WPF objects are not HWND based. Then how does it communicate with window handle? Yes, this question comes into the mind of every programmer who starts working with WPF after having considerable amount of exposure in the Windows environment.

First of all, OS cannot render any object without having a reference to HWND to its kernel. Hence is the case with WPF. So WPF window actually holds a reference to one window handle. Even you can get Window Handle for any Visual inside the WPF window.

ListBox lst = new</span /> ListBox();
HwndSource source = (HwndSource)HwndSource.FromVisual(lst);
IntPtr</span /> hWnd = source.Handle;

So this is a very basic step to get HWND data for any visual. Similarly, for a Window, you can get the Window Handle using:

WindowInteropHelper windowHwnd =new WindowInteropHelper(this</span />); 
IntPtr</span /> hWnd = windowHwnd.Handle;

So basically the WindowInteropHelper will give you the HANDLE for the outside window.

So does it mean every WPF object has a HANDLE associated with it? Actually, the case is something different than what looks like. WPF window is made up of two parts.

  1. Window area which is made up of Operating System Window
  2. Non - Window area which is inside a WPF window

Now, a WPF window being a ContentControl holds everything as its Content. So you can say every pixel of the Content inside the Window class is held by the Outside window. Every Visual of WPF does not have its own HANDLE associated with it, rather it is a content for the outside window element. To examine:

ListBox lst = new</span /> ListBox();
HwndSource lstHwnd = HwndSource.FromVisual(lst) as</span /> HwndSource;
WindowInteropHelper windowHwnd =new WindowInteropHelper(this</span />);

Debug.Assert(lstHwnd.Handle == windowHwnd.Handle);

The assertion outputs true. Hence you can say, every WPF control is owned by its parent window.

Except popup class, every control is drawn over the screen using Vector Graphics and hence does not correspond to its own Handle whatever.

Thank you for reading.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Abhishek Sur
India India
Did you like his post?

Oh, lets go a bit further to know him better.
Visit his Website : to know more about Abhishek.

Abhishek also authored a book on .NET 4.5 Features and recommends you to read it, you will learn a lot from it.

Basically he is from India, who loves to explore the .NET world. He loves to code and in his leisure you always find him talking about technical stuffs.

Working as a VP product of APPSeCONNECT, an integration platform of future, he does all sort of innovation around the product.

Have any problem? Write to him in his Forum.

You can also mail him directly to

Want a Coder like him for your project?
Drop him a mail to

Visit His Blog

Dotnet Tricks and Tips

Dont forget to vote or share your comments about his Writing

You may also be interested in...


Comments and Discussions

Generalcommunicate with child objects Pin
Angelo Munoz6-Dec-10 3:45
memberAngelo Munoz6-Dec-10 3:45 
GeneralRe: communicate with child objects Pin
Abhishek Sur6-Dec-10 7:51
mvpAbhishek Sur6-Dec-10 7:51 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

Permalink | Advertise | Privacy | Terms of Use | Mobile
Web04 | 2.8.180515.1 | Last Updated 5 Dec 2010
Article Copyright 2010 by Abhishek Sur
Everything else Copyright © CodeProject, 1999-2018
Layout: fixed | fluid