Custom windowing backend?

[SirusDoma]

Hi, I am pretty new to RmlUI, and I saw a couple of great samples in the README where people are writing custom apps with it.
I plan to create my own too, but I am still not sure about one thing: Am I supposed to write a custom backend from scratch if I want to implement custom windowing?

The perfect example is the alt:V installer shown in README.md. It has a custom title bar without an OS window frame and rounded corners. I'd like to create something similar that works across multiple platforms, and I really wish this were supported out of the box.

[mikke89]

Hello!

This should be relatively easy. Our backends come with very basic window management. You can easily extend those to e.g. start without window borders.

You can for example start with our sdl gl3 backend and build from there. This is already cross platform. Create the window with SDL_WINDOW_BORDERLESS to remove the borders.

Good luck! Don't be afraid to ask any questions, and please do show us your creations! :)

[SirusDoma]

Thank you for getting back! I ended up using GLFW instead. I am not familiar with SDL, but I assume it might result in a larger final build size than GLFW. I'd like to keep it as small as possible, with static linking.

I feel like this should be part of built in backend to support making borderless window (and maybe custom window dragging), since I think this should be common thing with RmlUI.

Anyway, I tried to import my html made using tailwind css, and it looked horrible when I tried to import it into rml+rcss

The problem disappears if I use a very large window, but if it is only slightly larger (or the same size as the layout), the layout breaks. Using a big window isn't ideal, since the unused/transparent area is still considered part of the window, which blocks a lot of space.

After struggling to make it work for about an hour, I decided to rewrite my html completely, and finally it worked. I am not sure of the root cause, but it is so frustrating. This is worth the trouble though!

[SirusDoma]

I would suggest adding a sample for this. It would be extremely helpful for people who are especially not really familiar with windowing stuff

[mikke89]

Yeah, GLFW should be a perfectly good choice here.

Looks really nice! Can't really be of much help without any sources on the first one, but seeing you fixed it already.

There has been some considerations around making one or more standalone samples, so yeah, could be a good idea. We try to keep the backends very minimal, as they are meant as a starting point for customizations. There's a lot of different things users want to do with it and add to it, and rather than satisfying everyone I want to keep it lean and give people a good starting point. But I'll keep your feedback in mind.

[SirusDoma]

I see, if built-in backends are intended to be a boilerplate for a custom backend, then one or two samples would be great 👍

Otherwise, I have a final question: do you have any tips to reduce the final build size? I tried minsizerel already, and the final executable is 2 MB-ish. I would like it smaller, maybe 1 MB or less.

I don't mind forking and removing some unused internals, too, if that's feasible. I saw that the sample executables are only a hundred KB, but rmlui seems to be 1.7 MB.

[mikke89]

Yeah, our core library should be somewhere below 2 MB. If you need something smaller than that you'll probably have to go surgical with the library :)