Question: How to migrate a simple Win32 app to WinUI 3.0

I’m currently attempting to figure out how to port my Win32 application to WinUI 3.0. To better understand how basic things are done I’m trying to turn this Microsoft Win32 sample app into a C++/WinRT based WinUI 3.0 app.

To do so I have installed the Visual Studio WinUI 3.0 Project Templates and have created a new project from the “Blank App, Packaged (WinUI in Desktop)” template. However, there are many things that are unclear to me and I hope some kind soul might help me along with some hints. I stumbled over the following very basic issues:

1. The wWinMain function in the mentioned sample sets up the message loop. Where do I need to set the message loop up in WinUI 3.0?
2. Where would I attach the WndProc callback function that processes the messages?
3. The sample draws on the window by obtaining an HDC using the GetDC function. How does this translate to WinUI 3.0? Am I able to draw into a window by simply obtaining the window’s HDC as well?

[janos-ijgyarto]

Seconded. I also have an old Win32 project that I would like to boost using WinUI, and the sample linked by the OP covers most of the use cases involved. The documentation keeps pointing to XAML Islands, but there is no comprehensive guide that describes, from start to finish, how to take a legacy project (i.e without any configuration for WinUI) and setting it up to use WinUI.

[anawishnoff]

Most of our team is on holiday break now, but I’m hoping when we return in Jan someone from the engineering side will be able to answer your specific questions, @ackh. Sorry about the delay here.

@janos-ijgyarto - as for documentation for migrating apps to WinUI 3, I know that this is a gap in our documentation. This is something we’re hoping and aiming to provide at the WinUI 3.0 release, so stay tuned.