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microui+fenster=small gui

September 7, 2024

Sometimes I just want to put pixels on a screen. I don't want to
think about SDL this or OpenGL that--I just want to draw my pixel
buffer and be done.

fenster, a tiny 2D canvas library by Serge Zaitsev, does just that.
It's a tiny drop-in header-only C/C++ file that weighs no more than
400 LOC of pretty readable code. It works with WinAPI, Cocoa, and
X11. And it handles keyboard and mouse input, too!

Sometimes I want to do just a little more than draw pixels--maybe have
a menu, some buttons, render text--and I don't want to completely DIY
but I still don't want to think about SDL.

Fortunately, microui by rxi exists and handles the translation from
GUI elements into a simple retargetable drawing bytecode. It's
similarly a small, drop-in library, weighing only 1500 LOC.

Unfortunately, the demo program uses SDL as a backend for the
bytecode. I'd been meaning to see if I could instead use fenster but
understanding what a "quad" was or what "glScissor" did seemed
intimidating. The project went nowhere.

Then, as usual, Kartik and I had a small argument and that resulted
in us creating the fenster backend for microui! I sent him a skeleton
to show what I wanted to do and he did most of the heavy lifting for
the OpenGL-like parts.

The result is a less than 250 LOC file that binds microui to fenster.
It's inspired by the SDL renderer demo, but with a couple of added
functions to abstract away keys and mouse buttons. It's hacky and
there's some stuff we still don't understand, but it works! And by
"works" I mean draws the expected demo windows, handles mouse hover
and click, and handles keyboard input.

Things left to figure out:

  * How to determine when to render from the texture and when from
    the provided drawing command's color
  * Mod keys like so that, for example, Shift+1 renders !
  * Scrolling

Check it out here. It's designed to all be dropped directly into your
project.

microui+fenster demo window in X11

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