Pangocairo show_layout function gives the following error during runtime:
Pango-CRITICAL **: 18:11:02.823: pango_font_description_set_size: assertion 'size >= 0' failed

Code used:

...
let (width, height) = (1000, 1000);
let surface = ImageSurface::create(Format::ARgb32, width, height).expect("Can't create surface");
let cr = Context::new(&surface);

let mut fontdescription = pango::FontDescription::from_string("Sans");
fontdescription.set_size(16 * pango::SCALE);
let pangolayout = pangocairo::functions::create_layout(&cr).unwrap();
pangolayout.set_font_description(Some(&fontdescription));
pangolayout.set_text("the quick brown fox jumps over the lazy dog");

pangocairo::functions::show_layout(&cr, &pangolayout);

The exact C equivalent that does not produce the error:

...
PangoLayout *layout;
PangoFontDescription *desc;
layout = pango_cairo_create_layout (cr);
desc = pango_font_description_from_string ("Sans");
pango_font_description_set_size(desc, 16 * PANGO_SCALE);
pango_layout_set_font_description (layout, desc);
pango_layout_set_text(layout, "the quick brown fox jumps over the lazy dog", -1);
pango_font_description_free(desc);

pango_cairo_show_layout(cr, layout);

I might just be doing this wrong, but I would like to clear the default font_map so that it can be reimported next time it is needed and pick up any new fonts that have been added. I see that I can set a new font_map with set_default, but it expects a font_map reference as input. See here:

https://github.com/gtk-rs/pangocairo/blob/master/src/auto/font_map.rs#L42

I'm new to rust, so I might be missing some way of getting it to work with the current code by casting ptr.null_mut() to a font_map. Seems very un-rusty. Would it be possible to allow this? Either by modifying set_default, or, maybe better, by adding a clear_default() method.

hey 👋

I'm trying to use https://github.com/servo/rust-fontconfig with pangocairo. I use pangocairo::FontMap::new_for_font_type(cairo::FontType::FontTypeFt) to create a new PangoCairoFcFontMap. And I need to use some functions from this interface, but no rust wrappers exist atm.

What's the best way to get them exposed? I am interested in this method specifically - https://github.com/GNOME/pango/blob/master/pango/pangofc-fontmap.c#L1928

I didn't check what exactly the problem is but calling pangocairo::FontMap::get_default() from multiple threads at once seems to sometimes cause interesting crashes, probably due to initialization (maybe even one-time initialization) inside pangocairo not being thread-safe.

I don't know if the same applies to functions of pango itself too.

Just filing this now so I don't forget, it's a known problem with pango/pangocairo but I don't have the time to collect the details now.

When trying to combine this crate with e.g. https://github.com/sdroege/gobject-subclass, you get conflicts for the -sys crates since in this one, you're specifying actual versions, unlike the other crates from gtk-rs.