Declarative UI for e-Paper, in Rust.

fn body(&self) -> impl View<Self::Message> {
  NavigationScreen::new(ScrollView::new(vstack![14;
    // A stepper is one focus stop but three touch targets: the two
    // glyphs nudge, the track sets an absolute value.
    // The name and the number are the control's, not the screen's. A
    // screen cannot draw the number: while an edit is open the
    // framework holds the value and does not tell the screen, so a
    // label built in `update` stands still while the track moves.
    Stepper::new(self.brightness)
      .on_change(ControlsMsg::Brightness)
      .on_step(ControlsMsg::BrightnessStep)
      .title("Brightness")
      .readout("%"),

    Slider::new(self.warmth, 100)
      .on_change(ControlsMsg::Warmth)
      .title("Warmth")
      .readout("%"),

    Divider::new(),

    Toggle::new("Frontlight", self.frontlight, "On", "Off")
      .on_change(ControlsMsg::Frontlight),

    Text::new("Downloading").font(Font::ui_small()),
    ProgressBar::percent(self.downloaded),
  ]))
  .title("Controls")
  .hints(
    Hint::Standard,
    Hint::Standard,
    Hint::text("-"),
    Hint::text("+"),
  )
}