Enable antialiasing using Xlib

Question

I'm trying to develop a custom set of libraries for creating GUIs in Linux, with, you know, widgets, buttons, etc. So I'm now learning to creating user interfaces using X11 and its Xlib. I get to the point of having a nice window of a size specified, at a position specified, of a specified background color, and the possibility of drawing points, rectangles, arcs. However as I drew my first circle I got really disappointed by the fact that the circle is not antialiased. I can see every single pixel as a square.

Now the question is easy. Is there any way to tell X: please antialias anything before drawing? Or do I have to avoid using XDrawArc and use a custom function which calls XDrawPoint for each point of the circle? Or there is a third solution?

Thanks in advance.

Answer 1

The short answer is "no". Xlib doesn't do anti-aliasing.

The longer answer is "you can use a higher level API such as Cairo Graphics". It's not necessary to roll your own.

Answer 2

What you encountered are the limitations of the X11 core protocol; technically it would be perfectly possible to add antialiasing to it, but that didn't happen.

Instead there's the XRender extension, that provides nice antialiased primitives. You'll also want to look into Xft to render antialiased text using vector fonts.