GitLab

This commit adds a new meson option -Dupdate_screenshots=true.
When it is enabled, and -Dgtk_doc=true is also used, then the
build will generate images to include in the API docs from
ui files in docs/reference/gtk/images.

Note: we still keep a copy of the images in git, in order to
allow building without a display connection. To update the
images in git, the generated images need to be copied back
from the builddir to the srcdir.

By default, 'docutils' installs 'rst2man' as 'rst2man.py'. Amend the
check for 'rst2man' to look for 'rst2man.py' as well if 'rst2man' is
not found.

And only enable `--fatal-warnings` if `-Dwerror` has been set, just like
we do for the introspection data generation.

It's easier to write than DocBook, and rst2man is faster than xsltproc.

And install the gi-docgen project file as well.

We want to fail the CI pipeline when the documentation generator emits a
warning.

Installing them even when manpages are enabled, but the demos are
disabled, produces manpages for unavailable programs...

We are building them, but not installing them.

Matthias Clasen authored Feb 19, 2021 and Emmanuele Bassi committed Mar 11, 2021

We have all the images, lets put them to use.

We are only interested in the warnings and errors.

We don't use gtk-doc to generate our API reference, so we don't need its
files lying around any more.

Stop using gtk-doc, and switch to gi-docgen.

The gi-docgen tool generates API references through the introspection
data, which has various benefits:

 - it does not parse C code
 - it does not generate and run C code to introspect types at build time
 - it does not present a different API from the one we're exporting

Additionally, gi-docgen:

 - does not generate DocBook XML in order to generate HTML
 - does not go through xsltproc
 - parses proper Markdown

Which makes it markedly faster than gtk-doc has ever been.

We have nice illustrations for this, lets use them.

The type is private, so making functions operating on it public is
pointless.

We use __builtin_popcount() in a couple of places, so it makes sense to
have it in one header.

To make this possible enable the doc shooter
to take screenshots of popovers.

It has been missing far too long.

Document that GtkListView, GtkColumnView and GtkListBox
support .rich-list, .navigation-sidebar and .data-table
style classes.

We no longer use this widget anywhere.

No longer a public widget.