Painter not updating as expected

[covercash2]

Description

given some state:

pub struct State {
    string: String,
}

creating a druid::widget::Painter to indicate the state should dynamically change the style of the widget. we can also add a druid::widget::Label to represent the state.

with the Label added, the app acts as intended (a "good" state is when string.len() is even):

however, when the Label is absent, the Painter no longer updates as expected, when the text in the TextBox is updated:

however, unfocusing the window will trigger the Painter to draw correctly:

what we have so far

my env is... esoteric. Arch Linux 5.6.11, i3 + Xorg, GTK3 3.24.20, but i also reproduced this on my macbook, macOS Mojave 10.14.6.

gdb and ole fashioned print debugging show that the closure passed to Painter is being run -- color is updated, values are calculated, etc. --, but i haven't dug into the ctx.stroke or ctx.fill enough to know exactly what is happening, and i'm still learning the draw system in general (i'm pretty new to druid).

i worked up this minimal example, but my original widget was a simple file viewer, using a more complicated state including things like PathBuf and some homebrewed druid::Data types. the basic behavior is the same, though. anyway, i pressed on thinking that something else in the hierarchy might trigger the redraw, and i was right! but this seems like a bug, so i went ahead and opened an issue.

code: https://gist.github.com/covercash2/0ef3185cf25635900363da5b71e4e268
gifs: https://imgur.com/a/ausXF2u

[jneem]

This sounds like a partial invalidation issue, particularly since it fixes itself when you change focus. I'll take a look.