02/09/2021

I recently had to build a demo for work and needed a GUI frontend. Generally my go to UI framework is Windows Presentation Foundation (WPF). It is super robust and covers pretty much everything you would want out of a UI Framework. The one giant downside is that its primarily geared towards being used with .NET languages such as C#. This in general means that you need to write the front end of your application in C# or C++/CLI and the interop down into native C++ for the bulk of your application. i.e. its a giant PITA.

WPF is being supplanted by WinUI. Unfortunately, at the time this still isn't quite up to snuff for building native C++ applications that aren't UWP centric (version WinUI 3.0 is still in Preview). Thus, I passed on trying this. For a good overview of the differences between WPF and WinUI see this excellent article: Building Modern Desktop Apps—Is WinUI 3.0 the Way to Go? (telerik.com).

So, if I need to build a fully native application, my general go to framework for UI has been wxWidgets. Then my boss pointed me to Dear ImGui. When I first read how this works, I was super skeptical. It's a fully Immediate mode UI. i.e. every frame you recreate the entire UI and the application maintains all state. This sounds nuts. However, it's freaking awesome for building fast small demos. The thing I didn't think about is that you often end up indirectly maintaining state anyways by implementing callbacks that have to copy values from the underlying UI into your application anyways. It's way simpler just to have the UI write directly to the place you are going to copy the values to anyways. Also, much of the mundane work that would have to be implemented by the application (i.e. keyboard/mouse input, windowing support, etc) has been written for whatever rendering framework (i.e. DX11, DX10, ...) you are using. Thus you application can make a few simple calls during its rendering loop and get all this functionality. Below is some sample code from my demo along with a screen shot of the demo's output showing some of the UI elements possible (checkboxes, sliders, image windows, etc).

Sample Output: