Can't render arabic text in Labels, Buttons and other widgets

[nomad-scl]

basically if I try to do this :

let btn = Button::new("ابدأ");
let label = Label::new("عدد").padding(5.0).center();
Flex::column().with_child(btn).with_child(label)

the button and the label are in the form but the text is empty
also I tried using the arabic_reshaper crate (which works in terminal and in image proc to render arabic text correctly) like this

let btn = Button::new(arabic_reshape("ابدأ"));
let label = Label::new(arabic_reshape("عدد")).padding(5.0).center();
Flex::column().with_child(btn).with_child(label)

but the problem is the same

[psychon]

What backend are you using?

I just replaced "Clear" in the flex example with "ابدأ" and the result when run with the Gtk backend is... well, different than "but the text is empty":

I get the same result with the x11 backend.

The same text looks different in my browser and yet again different in gvim (but at least there it does not "bleed into the surrounding").

[psychon]

I would guess that piet has some problems with right-to-left text.

diff --git a/druid/src/widget/label.rs b/druid/src/widget/label.rs
index cd3cb661..e717d07c 100644
--- a/druid/src/widget/label.rs
+++ b/druid/src/widget/label.rs
@@ -604,11 +604,13 @@ impl<T: TextStorage> Widget<T> for RawLabel<T> {
         self.layout.rebuild_if_needed(ctx.text(), env);
 
         let text_metrics = self.layout.layout_metrics();
+        println!("{:?}", text_metrics);
         ctx.set_baseline_offset(text_metrics.size.height - text_metrics.first_baseline);
         let size = bc.constrain(Size::new(
             text_metrics.size.width + 2. * LABEL_X_PADDING,
             text_metrics.size.height,
         ));
+        println!("{:?}", size);
         trace!("Computed size: {}", size);
         size
     }

results in

LayoutMetrics { size: 0.0W×18.0H, first_baseline: 14.0, trailing_whitespace_width: 20.0 }
4.0W×18.0H

A width of zero seems... insufficient.

Edit: Possibly related: linebender/piet#432

[raphlinus]

We are definitely not officially supporting BiDi yet, but hope to in a future cycle.

[cmyr]

This is also going to be highly backend specific. The situation may be worse on linux than on macos or windows. That said, RTL text (but not BiDi) is supported in piet, so it's possible this is just an error in the integration?

@nomad-rst can you confirm that you're on linux?

[nomad-scl]

I should have mentioned, I'm not on Linux, the issue I posted above is me using windows 10 x64
also regarding @psychon post above on what backend am I not using any backend I just added druid to my cargo.toml file and was able to run things from the examples

[cmyr]

@nomad-rst when you run a druid app, druid auto-selects an appropriate 'backend' based on your platform; e.g. on windows it uses the windows backend. :)

[psychon]

@cmyr Please also tag this with shell/gtk and shell/x11 as per #1819 (comment) (although this might also be a different issue, it still looks similar enough to me....)

[cmyr]

Hmm interesting. This does appear to be working on macOS, so I'm not sure if these will end up being exactly the same bugs or not.