I have a HWND written by C++ and we hope added it to content page in MAUI, so how should we handle this case?

I'm not sure what you mean by "adding it to content page". In the future can you please provide more details on what specifically you are trying to do? See How to write a quality question That said, HWNDs and ContentPages work at different levels. There isn't a direct mapping, and you can't host an HWND in a MAUI control or vice versa. MAUI on Windows uses WinUI 3. There is an HWND for the top-level Window, but children of that Windows (such as a ContentPage) are windowless controls and don't have HWNDs. See MAUI Fundementals Windows for more on the Window object. See [Manage app windows (Windows App SDK) / UI framework and HWND interop]( https://learn.microsoft.com/en-us/windows/apps/windows-app-sdk/windowing/windowing-overview#ui-framework-and-hwnd-interop] See Retrieve a window handle (HWND) / WinUI 3 with C++ for how to get an HWND from a WinUI Window. To get the top-level window you need to drop out of MAUI into platform specific code and get the WinUI WindowHandle from the Window's Handler's PlatformView. Obviously non-Windows platforms won't have HWNDs. #if WINDOWS var hwnd = ((MauiWinUIWindow)App.Current.Windows[0].Handler.PlatformView).WindowHandle; #endif

How to get HWND handler from content page in MAUI

Accepted answer

Rob Caplan - MSFT 5,412 Reputation points Microsoft Employee

2022-06-14T17:42:04.927+00:00
I'm not sure what you mean by "adding it to content page". In the future can you please provide more details on what specifically you are trying to do? See How to write a quality question

That said, HWNDs and ContentPages work at different levels. There isn't a direct mapping, and you can't host an HWND in a MAUI control or vice versa. MAUI on Windows uses WinUI 3. There is an HWND for the top-level Window, but children of that Windows (such as a ContentPage) are windowless controls and don't have HWNDs.

See MAUI Fundementals Windows for more on the Window object.
See [Manage app windows (Windows App SDK) / UI framework and HWND interop](https://learn.microsoft.com/en-us/windows/apps/windows-app-sdk/windowing/windowing-overview#ui-framework-and-hwnd-interop]
See Retrieve a window handle (HWND) / WinUI 3 with C++ for how to get an HWND from a WinUI Window.

To get the top-level window you need to drop out of MAUI into platform specific code and get the WinUI WindowHandle from the Window's Handler's PlatformView. Obviously non-Windows platforms won't have HWNDs.

#if WINDOWS var hwnd = ((MauiWinUIWindow)App.Current.Windows[0].Handler.PlatformView).WindowHandle; #endif
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Yang Yang 46 Reputation points

2022-06-15T01:01:41.85+00:00

Thanks for your answer, Rob. Here I have a 3rd party libarary with which we can create a HWND, I'd like to embed this HWND into an application written with MAUI. Indeed I'd like to embed it into a specific position of main window. As traditional MFC application, each part of main window is a separate view and view owns a HWND handler. So I assume the ContentPage also owns a HWND handler then I can set it as parent of the HWND created from 3rd party library.

Rob Caplan - MSFT 5,412 Reputation points Microsoft Employee

2022-06-15T21:31:36.397+00:00

As traditional MFC application, each part of main window is a separate view and view owns a HWND handler. So I assume the ContentPage also owns a HWND handler then I can set it as parent of the HWND created from 3rd party library.

Most modern UI stacks, and specifically the WinUI3 stack that MAUI uses on Windows, do not use separate HWNDs for each child control. There's only one HWND for the container window, and all of the controls inside are rendered directly into that HWND.

You can use UI Automation to find information about the ContentPage such as its location within the container HWND and on screen, and you may be able to float your HWND on top of that, but it will be tricky to erase the seams between the separate windows. You'll likely run into some airspace issues since the HWND won't blend with the page controls.

--Rob

JD 0 Reputation points

2023-03-19T13:55:53.5+00:00

@Rob Caplan - MSFT
Hey Rob,

Thanks for the answers you've provided regarding HWND and MAUI.

I'd like to render native OpenGL content in MAUI. In WPF this is accomplished using HwndHost and some interop methods in managed code, and wglCreateContext in native code.

I realize the implementation for rendering contexts will be platform-specific, but I wonder the best way to include my natively rendered content in MAUI. Perhaps there is another way of creating native OpenGL contexts or something I'm missing (the custom renderers https://learn.microsoft.com/en-us/dotnet/maui/migration/custom-renderers?view=net-maui-7.0 look interesting as well...)

I will test feasibility of using the top-level window handle (on Windows platform), although I suspect there will be some challenges like you mentioned.

Thanks for your insight,

Justin Pierce
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How to get HWND handler from content page in MAUI

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