Shapes example

[scrouthtv]

TLDR: How to create a window and draw / fill things using xproto:

(the white border outside the black border is generated by my WM, should not be there for you)

A bit of backstory: I originally got into xgb because I was working on a go implementation of the xwd (x window dump) file format and I needed to create small windows with randomly colored pixels, something like this:

So I got into xproto and how to create images and such.

I cloned this example originally from Alex Kesling's testing which is basically a Go copy of an example in the xcb documentation.

I adapted some things to go nicer along the create-window example, added commentary and some more things (e. g. drawing text and filling a rectangle).

[scrouthtv]

When I first was trying to use xproto, I couldn't figure out how I'd get the drawable that was needed for drawing.

I wanted one of the core aspects of this example to be demonstrating that the drawable is (for very basic use cases) the window itself.

[jezek]

I took the libery to fix typos and reword a comment.
I had some difficulties running the example on Ubuntu (see comments near font).

Note: As you can see, I was able to push commit directly to your master branch. This is because you gave me permission to edit your PR. It's better practice to start a PR from a branch, so the maintainer (if granted privileges) can only edit the branch (and not master directly).

[jezek]

I've got an:

Failed opening the font: BadName {NiceName: Name, Sequence: 8, BadValue: 67108870, MinorOpcode: 0, MajorOpcode: 45}

on Ubuntu MATE 20.10

[scrouthtv]

What are we going to do about the missing font issue?

The example font that is often used is simply fixed (which is afaik installed by X).

However, I also want to demonstrate writing UTF8 characters (the ö), but fixed does only have a very limited character set.

I tried finding a font that would be preinstalled on many systems, looks like that didn't work out.

It is possible to see the available fonts using xfontsel.
xproto can also list available fonts to the developer using ListFonts().

However, I don't know how to determine which of these support unicode characters.

[scrouthtv]

Could you kindly try the font spec
-*-*-*-*-*-*-14-*-*-*-*-*-iso10646-1

[jezek]

However, I also want to demonstrate writing UTF8 characters (the ö), but fixed does only have a very limited character set.

I don't have a problem with fixed.

But with unicode and fonts it's a little bit tricky (I think). If I wanted "more unicode" demonstration, I would pick a text like Hellö 世界!, where the fixed font will fail like the -*-*-*-*-*-*-14-*-*-*-*-*-iso10646-1 font (and maybe the -gnu-unifont-*-*-*-*-16-*-*-*-*-*-*-* too).

I'm a little bit in the dark, how to handle this, there is no easy solution (If there is, I would like to know). Few thing come into my mind, like bundle font with app and/or use enviroment variables, input flags or some config file to let the user choose desired font. But for simplicity of this example, I would go with fixed and leave a comment about some possible drawbacks.

[scrouthtv]

I don't have a problem with fixed.

I just tried again, and now it's working for me too. I guess I just had something wrong during my first tries.

-*-*-*-*-*-*-14-*-*-*-*-*-iso10646-1

This simply selectes any font that is iso10646-1 encoded, which is basically the character encoding of Unicode. So any of these fonts should have at least a basic set of extended latin characters.

But for simplicity of this example, I would go with fixed and leave a comment about some possible drawbacks.

Sounds good!