razcore-rad / zig-gobject-fun

Fork of https://gitlab.com/LARathbone/gobject-fun to explore Zig + GTK4

Zig - GTK4 Exploration

The original C repo

The Zig-implementation lives in youtube-tutorial.

Zig has the capability to translate C code to Zig code using a CLI tool via zig translate-c or in code with the built-in function @cImport().

Unfortunately Zig isn't capable of translating complex C code that heavily relies on macros like GTK4. Because of this, we aren't able to create custom widgets in a simple fashion.

The compromise I'm using is to create the boilerplate code in C while implementing the "heavy-lifting" methods in Zig.

Status

Zig data types carry extra information (like alignment) compared to C so it isn't trivial to use C pointer types directly in Zig. A lot of explicit casting has to take place, which in fairness happens in C as well, but the GTK4 macros masks out most of this noise.

That said, the idea is to convert as much C code to Zig while retaining sanity:

• youtube-tutorial/1. The custom method (if we stick with the OOP metaphor) implementations are moved to demowidget.zig. These are all under an opaque type called DemoWidget exposing a canonical Zig function-calling scheme.

  • demo_widget_init().
  • demo_widget_dispose().
  • demo_widget_finalize().
  • demo_widget_class_init().
  • A public "ziggified" version of demo_widget_new() to DemoWidget.new().
  • Helper "ziggified" functions for internal use: DemoWidget.get_parent_class(), DemoWidget.get_button(), DemoWidget.set_button(). These are required because DemoWidget is an opaque type, and we can't access fields directly. The setter/getter implementation is on the C side in demowidget.c.

• youtube-tutorial/2

• youtube-tutorial/3

• youtube-tutorial/4. At this point I determined that there is wayyyyyy too much hassle dealing with explicit casts that need to happen on almost every line of code so using GTK4 via translate-c is impractical. We should wait for some awesome people to create actual Zig bindings.

• youtube-tutorial/5

• youtube-tutorial/6

Conclusion

Although I learned a lot about Zig during this experiment I would not advise anyone to interoperate with C via translate-c directly when dealing with complex libraries like GTK4.

The only practical application for translate-c is for libraries that generate bindings really, anything more get too complex because of explicit casting needed at almost every line.

I'm keeping this repo around as a showcase.

Building

Go into any youtube-tutorial/* subfolder and execute zig build run to build and run the app.

Dependencies

• libgtk-4-dev

Acknowledgements

This work is not possible without the GTK4 tutorial by Logan Rathbone and atoft's Reactions GIF search app that put me on the right track to understanding how to interoperate with GTK4 in C.