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Fluid is a library I started developing 3 years ago when I joined the D community, after failing to find a suitable library for my gamedev project. Developing user interfaces through websites, games or applications is something I've spent a significant amount of time in the past, so I saw this as an opportunity for developing a solution that combines the best aspects of different frameworks I have previously used, whereas targeted at web browsers, mobile applications, games or desktop. Similarly to how many praise D for being both great for prototyping and amazingly scalable, I found that I would love to build something that shares both of those traits.
Fluid is a flexible UI library for the D programming language. Minimal setup. Declarative. Non-intrusive.
auto root = vspace(
.layout!"center",
label(
.layout!"center",
"Hello World from"
),
imageView("./logo.png"),
);
Fluid is not standalone, but relies on other libraries to provide input and output facilities. It comes with build in support for Raylib 5 and arsd.simpledisplay. Integration is seamless, as one or two calls do the job.
while (!WindowShouldClose) {
BeginDrawing();
ClearBackground(color!"#fff");
root.draw();
EndDrawing();
}
Fluid comes with a number of helpful nodes that you can use to build your interface. Communicate with the user using label, button, textInput, fileInput, scrollInput, and quickly build layouts using simple and easy to learn space, frame, nodeSlot, grid, mapSpace.
Fluid exposes a high-level API, provides layout capabilities that are responsive-by-default, Unicode support and text rendering with Freetype2, reliable mouse, keyboard and gamepad support, is themable, extensible and looks great on HiDPI displays.
Supported platforms: Windows, Linux, macOS*, with plans to support Android and WASM.
The showcase should be a nice introduction to the library, describing each feature, providing live examples and code snippets. It's still a work in progress, so don't expect it to be complete nor perfect by any means, but I hope to improve it with further updates.
dub run fluid:showcase
If you'd like to start a new DUB projects with Fluid, you can start with a template:
dub init -t fluid
Release 0.6.0
While I still have work to do to make Fluid as good as I want it to be, both in regards of performance and usability, I believe that 0.6.0, being the biggest update yet, is a breakthrough moment in Fluid's development, and the library is only about to gain stability.
Most importantly, 0.6.0 is the first release to no longer exclusively rely on Raylib. As noted earlier, it's already possible to use Fluid with arsd.simpledisplay. This opens a lot of new possibilities, since Fluid could be used with anything as long as you implement the FluidBackend interface.
This release also completely reworked input, making the entire interface immediately controllable with tabs and arrow keys. All mouse, keyboard and gamepad binds are configurable and can easily be used in user-provided nodes via Input Actions. It is also the first to introduce the new showcase. A full changelog is available on https://git.samerion.com/Samerion/Fluid/releases/tag/v0.6.0
The future
Fluid is still lacking a number of features. Speaking of numbers, no numberInput, for example. But having just reinforced the code of the library, I think it's a great time to add all that is now missing, see https://git.samerion.com/Samerion/Fluid/issues/74. Despite of this, Fluid is already in a great state and can be used in practical scenarios. New nodes aren't difficult to add.
The roadmap for Fluid sees just two missing major pre-releases, with only one of them possibly introducing any greater breaking changes. The theming system needs a refactor, which I believe will make it more powerful and easier to use, and I plan to do so in 0.7.0.
Changes I made to the backend side of Fluid make it possible to expand the reach of Fluid. I'm interested in making it work with Hipreme Engine because of the engine's great portability. I'm also very excited to expand outside of game development and try and make the library integrate with naive UI frameworks or at least mimic their look.
Later on, along with 0.8.0, I plan to develop a graphical, live editor for Fluid user interfaces, with support for debugging and analysis of running programs.
Maintenance
It's typical for many D projects now that they come and go, libraries are born out of hobby projects just to be forgotten and abandoned later. Will this happen to Fluid?
Fluid has mostly been developed in bursts. Development slows downs or stops for some time, then resumes with me pushing a lot of changes and new features. This is a model that I find necessary since I'm the sole maintainer. Fluid however, has been in development for 3 years now, which bodes it well in regards to its future. Moreover, now almost every project of mine depends on Fluid in one way or another.
I'm active on the D language Discord, and in the future I might also consider the option of commercial support, if someone finds it needed.
Even if at this point Fluid doesn't satisfy all needs, I really hope in the future it'll grow to be a suitable solution for developing different kinds of user interfaces.
