gdi: x11: Add ARC Command

[RobLoach]

Fixes #112

The arc isn't quite right on x11. The bottom right on the canvas.

[RobLoach]

@bmuessig Mind giving it a review? I'm unable to test this one.

[bmuessig]

I've built the changes and the demo looks like this on Win32/GDI:

I'll give the same demo a try with SDL and post the result.

[bmuessig]

This is how it looks like using SDL:

So this fix is unfortunately not quite working. I will have a look what's going wrong.

[bmuessig]

Alright, I fixed it:

[RobLoach]

Thanks for fixing that up! Looks like from this Pull Request, there's the demo/x11/nuklear_xlib.h changes too. :thinking:

[bmuessig]

Thanks for fixing that up! Looks like from this Pull Request, there's the demo/x11/nuklear_xlib.h changes too. thinking

You're welcome :) Right, there still is the X11 binding, but unfortunately, I don't have a set-up to work on X11 apps right now, so I'm not much help there.

[riri]

Thanks for fixing that up! Looks like from this Pull Request, there's the demo/x11/nuklear_xlib.h changes too. thinking

I made the test for X11 on @RobLoach fork, and while the code for Xlib is added, it seems still broken:

I don't have time to investigate more in depth for now, so either the PR is merged knowing the invalid state of X11 part, either someone else (or me in the future) could find the issue with arc drawing?

[riri]

What's the status of this? I see in master the command for gdi is coded from commit cacdf6b I have implemented the x11 part in commit d63f106 Beside some whitespace fixes, are there improvements to add? If not maybe that PR could be closed?