makeover-immediate 0.50.0

//! The described things that are not fields, tables or frames.
//!
//! A meter, a token, a control, a figure, and a wait. `makeover-tui` has had
//! most of these since its
//! own `widget` module and this crate has not, which is the gap that showed up
//! the moment anything tried to draw a whole `quasi_router::Screen` in egui:
//! the screen walk had a renderer for the containers and nothing for four of the
//! nodes inside them, so the drawing would have landed in the consumer, one copy
//! per app. That is the divergence this suite exists to end, so it lands here.
//!
//! # What "in egui" changes, and what it does not
//!
//! The semantics are `makeover-tui`'s, deliberately: a meter is a bar and a
//! reading, a badge is round and a chip is square, a control names its key where
//! the description gave one, and a figure puts the movement on the value rather
//! than on the caption. Those are description-level readings and they do not get
//! a second opinion per host.
//!
//! What differs is forced by the target rather than chosen. A terminal spends a
//! whole cell on a character and returns a `Line` for the caller to place; egui
//! paints an arbitrary rect and answers a [`Response`], so every function here
//! draws into the `Ui` it is given and hands back what the user did to it. That
//! is also why nothing here takes a `focused` flag the way `makeover-tui`'s
//! `act` does: egui owns focus, which is the rule the crate header states.

use egui::{Align, Layout, Response, RichText, Sense, Ui, Vec2};
use makeover_layout::{Act, Awaiting, Bar, Chart, Figure, Meter, State, Token, Tone};
use makeover_timing::activity_blink;
use std::time::Duration;

use crate::Palette;

/// The sizes a widget cannot derive from the description.
///
/// Every number a caller might reasonably want different, in one place, on the
/// footing [`FrameStyle`](crate::FrameStyle) and [`FieldStyle`](crate::FieldStyle)
/// already establish: this crate owns no sizes.
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct WidgetStyle {
    /// How tall a meter's bar is drawn.
    pub meter_height: f32,
    /// How wide a meter's bar runs, or `None` to take the width on offer.
    ///
    /// `None` is the honest default in immediate mode: a bar in a side panel and
    /// a bar in a wide pane are the same description, and the available width is
    /// the only thing either of them knows.
    pub meter_width: Option<f32>,
    /// How tall a chart stands, in points.
    ///
    /// A chart's own, not [`meter_height`](Self::meter_height): a meter is a
    /// rule set into a line of text and a chart is a figure with room of its
    /// own. `makeover-webview` defers the same number to `--chart-height` for
    /// the same reason, and 200 is the same default.
    pub chart_height: f32,
    /// The corner radius on a meter's trough and on a token.
    pub radius: u8,
    /// Inside a token, around its label.
    pub token_padding: Vec2,
    /// Between a figure's value and its caption.
    pub figure_gap: f32,
    /// How much larger a figure's value is drawn than the body text.
    ///
    /// A multiplier rather than a size, so a figure scales with whatever text
    /// style the app has set rather than pinning a point size this crate has no
    /// business choosing.
    pub figure_scale: f32,
    /// The side of the activity mark, square.
    ///
    /// Small on purpose. The mark says one thing and a reader should have to
    /// look at it to read it, which is the difference between an indicator and
    /// an animation competing with the content it sits beside.
    pub mark_size: f32,
}

impl Default for WidgetStyle {
    /// Bars at 6pt taking the width on offer, a figure at double text size, and
    /// the activity mark a square a little larger than a bar is tall.
    fn default() -> Self {
        Self {
            meter_height: 6.0,
            meter_width: None,
            chart_height: 200.0,
            radius: 3,
            token_padding: Vec2::new(6.0, 2.0),
            figure_gap: 2.0,
            figure_scale: 2.0,
            mark_size: 8.0,
        }
    }
}

/// A proportion as a bar and a reading.
///
/// The reading is built here from the two numbers and the noun, for the reason
/// `makeover-tui` states: [`Meter::label`] carries the noun alone, so each
/// renderer picks its own sentence order rather than the description picking one
/// for all of them.
///
/// **A bar that has run over is drawn full and reads over.** `done` may exceed
/// `total` and that is the case worth drawing, per `Meter`'s own docs: the fill
/// is clamped because a rect cannot be longer than itself, and the reading is
/// not, because "9/6" is the fact the user needs. Clamping both would hide the
/// overrun entirely, which is the bug goingson's `is_over_estimate` flag exists
/// to recover from on the other side.
///
/// A zero `total` is no set rather than a complete one, so it draws empty.
pub fn meter(ui: &mut Ui, meter: &Meter<'_>, palette: &Palette, style: &WidgetStyle) -> Response {
    let width = style
        .meter_width
        .unwrap_or_else(|| ui.available_width().max(1.0));
    ui.horizontal(|ui| {
        let (rect, response) =
            ui.allocate_exact_size(Vec2::new(width, style.meter_height), Sense::hover());
        // The trough is the sunken surface rather than a tint of the tone: a
        // bar is a thing set into the page with something in it, which is what
        // `Fill::Sunken` means, and tinting the empty half would read as a
        // second, paler proportion.
        ui.painter().rect_filled(rect, style.radius, palette.sunken);
        let share = if meter.total == 0 {
            0.0
        } else {
            (f64::from(meter.done) / f64::from(meter.total)).min(1.0)
        };
        #[expect(
            clippy::cast_possible_truncation,
            reason = "a share is 0..=1 and the product is a width in points"
        )]
        let filled = (f64::from(rect.width()) * share) as f32;
        if filled > 0.0 {
            let mut fill = rect;
            fill.set_width(filled);
            ui.painter()
                .rect_filled(fill, style.radius, palette.tone(meter.tone));
        }
        let reading = match meter.label {
            Some(label) => format!("{}/{} {label}", meter.done, meter.total),
            None => format!("{}/{}", meter.done, meter.total),
        };
        ui.label(RichText::new(reading).color(palette.content_muted));
        response
    })
    .inner
}

/// A badge or a chip.
///
/// A badge is the table model's (wiki `table-model`), as `makeover-webview`
/// draws it: a fill of its tone surface inside a one-point edge in its tone,
/// the label in content ink. A neutral badge fills with the raised surface and
/// takes the border for its edge. The tone is never the ink, which measured
/// 1.34:1 as text on goingson's warning.
///
/// A chip is outlined in its tone, and filled while latched.
///
/// **A chip answers a click and a badge does not**, which is
/// [`Token::interactive`] and is the whole difference between the members. The
/// `Response` comes back either way, so a caller that presses a badge is
/// pressing something this function said was not interactive; the sense is what
/// makes egui agree.
///
/// `latched` is a chip that is switched on, and it fills rather than outlines. A
/// terminal has to collide latched with focus because it has one spare axis for
/// two facts; egui does not, so it does not.
///
/// A chip's removable half is not drawn, on `makeover-tui`'s reasoning: a second
/// control inside a token is a question for whoever owns the interaction rather
/// than for a drawing.
pub fn token(
    ui: &mut Ui,
    label: &str,
    kind: Token,
    tone: Tone,
    latched: bool,
    palette: &Palette,
    style: &WidgetStyle,
) -> Response {
    let painted = palette.tone(tone);
    let radius = style.radius;
    let sense = if kind.interactive() {
        Sense::click()
    } else {
        Sense::hover()
    };

    // Laid out before the rect is allocated, because a token is exactly as wide
    // as what it says plus its padding: there is no box to fit text into here,
    // the way a table cell has one.
    let ink = match kind {
        Token::Badge => palette.content,
        Token::Chip { .. } if latched => palette.page,
        Token::Chip { .. } => painted,
    };
    let galley = ui.painter().layout_no_wrap(
        label.to_owned(),
        egui::TextStyle::Body.resolve(ui.style()),
        ink,
    );
    let size = galley.size() + style.token_padding * 2.0;
    let (rect, response) = ui.allocate_exact_size(size, sense);

    if kind == Token::Badge {
        ui.painter().rect(
            rect,
            radius,
            palette.tone_surface(tone),
            egui::Stroke::new(1.0, palette.tone_edge(tone)),
            egui::StrokeKind::Inside,
        );
    } else if latched {
        ui.painter().rect_filled(rect, radius, painted);
    } else {
        ui.painter().rect_stroke(
            rect,
            radius,
            egui::Stroke::new(1.0, painted),
            egui::StrokeKind::Inside,
        );
    }
    ui.painter()
        .galley(rect.center() - galley.size() / 2.0, galley, ink);

    // Say what was drawn, because painting it says nothing.
    //
    // A token allocates its rect and paints the text straight onto it, so
    // nothing reached the accessibility tree at all until 2026-08-22: an
    // interactive chip was a control a mouse could press and a screen reader
    // could not find, and a badge was text nobody could read out. The filter
    // panel's twenty-four key pills were the site -- a whole way of filtering,
    // absent.
    //
    // A chip that latches says so through `selected`, which is what a screen
    // reader announces as pressed. That is `latched`'s whole meaning: the key
    // is held down.
    let role = if kind.interactive() {
        egui::WidgetType::Button
    } else {
        egui::WidgetType::Label
    };
    response.widget_info(|| {
        let mut info = egui::WidgetInfo::labeled(role, ui.is_enabled(), label);
        if kind.interactive() {
            info.selected = Some(latched);
        }
        info
    });
    response
}

/// A control.
///
/// The key the description named is drawn beside the label where there is one,
/// which is [`Act::key`] finally being read by a second renderer: it was written
/// for a terminal, and a desktop app has keys too.
///
/// **A disabled control is drawn and does not answer**, through
/// [`State::suppresses_interaction`] rather than a second reading of what
/// disabled means, and it takes [`Palette::content_muted`] because that is the
/// intent `State::Disabled` resolves to. egui is told through `add_enabled`, so
/// its own focus walk skips it: a control that is drawn and not reachable is
/// exactly what `disabled` means on every host, and here the host already has
/// the machinery.
pub fn act(ui: &mut Ui, act: &Act<'_>, palette: &Palette, _style: &WidgetStyle) -> Response {
    let disabled = act.state.is_some_and(State::suppresses_interaction);
    let label = match act.key {
        Some(key) => format!("{}  ({key})", act.label),
        None => act.label.to_owned(),
    };
    let colour = if disabled {
        palette.content_muted
    } else {
        palette.tone(act.tone)
    };
    let mut button = egui::Button::new(RichText::new(label).color(colour));
    // The control that commits wears a frame, which is this host's spelling of
    // the webview's default-button ring (`Act::commits`). Muted when disabled,
    // as the label is, so it keeps its shape without asking for a press.
    if act.commits {
        let frame = if disabled {
            palette.content_muted
        } else {
            palette.content
        };
        button = button.stroke(egui::Stroke::new(2.0, frame));
    }
    let drawn = ui.add_enabled(!disabled, button);
    // Standing help, as a hover, which is honest on this host in a way it is
    // not on a terminal: egui has a pointer. `makeover_tui` says the same
    // sentence as a muted row under the control.
    //
    // Drawn here rather than by the caller as of `Act::hint` (0.40.0). quasi's
    // egui renderer was doing exactly this outside the widget because
    // `layout::Act` carried no hint, so a host that was not quasi got nothing.
    match act.hint {
        Some(hint) => drawn.on_hover_text(hint),
        None => drawn,
    }
}

/// A figure: the value, then what it counts under it.
///
/// The tone lands on the value and its change rather than on the caption, which
/// is what [`Figure::tone`] means: the figure is an ordinary fact and it is the
/// movement that reads as good or bad. `makeover-tui` says the same thing with a
/// bold span; here it is a larger one, because egui can size text and a terminal
/// cannot.
pub fn figure(
    ui: &mut Ui,
    figure: &Figure<'_>,
    palette: &Palette,
    style: &WidgetStyle,
) -> Response {
    ui.with_layout(Layout::top_down(Align::Min), |ui| {
        let value = match figure.change {
            Some(change) => format!("{} {change}", figure.value),
            None => figure.value.to_owned(),
        };
        let size = egui::TextStyle::Body.resolve(ui.style()).size * style.figure_scale;
        let shown = ui.label(
            RichText::new(value)
                .color(palette.tone(figure.tone))
                .size(size)
                .strong(),
        );
        ui.add_space(style.figure_gap);
        ui.label(RichText::new(figure.caption).color(palette.content_muted));
        shown
    })
    .inner
}

/// What a host can see about a wait that is running.
///
/// Both halves are optional because both are the host's to observe and neither
/// is derivable from the description. `makeover_layout::Awaiting` says how big
/// the payload is; nothing in a description can say how much of it has landed,
/// because that is a fact about a transfer in flight.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub struct Progress {
    /// How much has arrived, in whatever unit the description counted.
    ///
    /// `None` means nothing is watching the transfer, which is the common case
    /// and is what keeps the bar from being drawn out of a total alone.
    pub delivered: Option<u64>,
    /// How long the wait has lasted so far.
    ///
    /// The one time value a wait is allowed to show. Never a remaining time and
    /// never a rate: see [`awaiting`].
    pub elapsed: Option<Duration>,
}

/// The activity mark: one small square, blinking.
///
/// Rule 2 of wiki `loading-and-progress-standard`, and the thing that replaced
/// `Ui::spinner` here. A spinner turns at a rate it invented and reads as
/// progress; this claims nothing beyond "something is happening", which is the
/// whole of what an unmeasured wait knows.
///
/// **`reduced` stills the mark rather than removing it.** egui has no
/// `prefers-reduced-motion`, so the preference arrives as a bool from whatever
/// the host asked its own platform, exactly as `makeover_timing::activity_blink`
/// is shaped for. A still mark still says something is happening; hiding it
/// would answer a request nobody made.
///
/// The cadence is `makeover_timing::Cadence::Activity` and is not a number this
/// crate chooses, so a browser, a terminal and an egui window blink together.
///
/// Repaint is asked for at the next flip rather than every frame: a blinking
/// mark should not turn a window that is otherwise idle into one that renders
/// continuously.
pub fn activity(ui: &mut Ui, reduced: bool, palette: &Palette, style: &WidgetStyle) -> Response {
    let (rect, response) = ui.allocate_exact_size(Vec2::splat(style.mark_size), Sense::hover());
    let lit = match activity_blink(reduced) {
        // Still, and lit. The state the mark holds when nothing may move.
        None => true,
        Some(half) => {
            let half = half.as_secs_f64();
            // A cadence of zero would divide by nothing and blink infinitely
            // fast, which is the one value the token cannot mean.
            if half <= 0.0 {
                true
            } else {
                let phase = ui.input(|input| input.time).rem_euclid(half * 2.0);
                let lit = phase < half;
                let next = if lit { half } else { half * 2.0 } - phase;
                ui.ctx()
                    .request_repaint_after(Duration::from_secs_f64(next.max(0.0)));
                lit
            }
        }
    };
    // Lit is the accent, dark is the trough it sits in. Not "drawn and not
    // drawn": a mark that vanishes half the time is a hole in the layout, and
    // the reader loses where to look between blinks.
    let colour = if lit { palette.action } else { palette.sunken };
    ui.painter().rect_filled(rect, style.radius, colour);
    response
}

/// A wait, drawn from what is actually known about it.
///
/// The branch is `Awaiting::is_determinate` and one more question the
/// description cannot answer: whether anything is watching the transfer. A bar
/// needs both a total and a numerator, so a described amount with no
/// [`Progress::delivered`] beside it draws the mark, not an empty trough that
/// implies someone is counting.
///
/// **What the bar may not do**, from rule 1 of wiki
/// `loading-and-progress-standard` and from `Awaiting`'s own docs: what is done
/// over what there is, plus the time it has taken. Never a remaining time, an
/// arrival time, or a rate extrapolated forward. A prediction is wrong the
/// moment the transfer stalls, and being confidently wrong is worse than being
/// honestly indeterminate.
///
/// The reading is the two raw numbers, as [`meter`] does it. The unit is the
/// app's — bytes for an upload, rows for an import — and a renderer that
/// guessed at one would be formatting a quantity it was deliberately not told
/// about.
pub fn awaiting(
    ui: &mut Ui,
    awaiting: Awaiting,
    progress: Progress,
    reduced: bool,
    palette: &Palette,
    style: &WidgetStyle,
) -> Response {
    let (Some(total), Some(done)) = (awaiting.amount, progress.delivered) else {
        return activity(ui, reduced, palette, style);
    };
    let width = style
        .meter_width
        .unwrap_or_else(|| ui.available_width().max(1.0));
    ui.horizontal(|ui| {
        let (rect, response) =
            ui.allocate_exact_size(Vec2::new(width, style.meter_height), Sense::hover());
        ui.painter().rect_filled(rect, style.radius, palette.sunken);
        // A total of zero is no payload rather than a finished one, which is
        // `meter`'s reading of the same case. Over-delivery clamps for the same
        // reason it does there: a rect cannot be longer than itself.
        let share = if total == 0 {
            0.0
        } else {
            #[expect(
                clippy::cast_precision_loss,
                reason = "a byte count past 2^53 is not a wait anyone is watching a bar for"
            )]
            let share = (done as f64 / total as f64).min(1.0);
            share
        };
        #[expect(
            clippy::cast_possible_truncation,
            reason = "a share is 0..=1 and the product is a width in points"
        )]
        let filled = (f64::from(rect.width()) * share) as f32;
        if filled > 0.0 {
            let mut fill = rect;
            fill.set_width(filled);
            ui.painter().rect_filled(fill, style.radius, palette.action);
        }
        let reading = match progress.elapsed {
            Some(elapsed) => format!("{done}/{total}  {}s", elapsed.as_secs()),
            None => format!("{done}/{total}"),
        };
        ui.label(RichText::new(reading).color(palette.content_muted));
        response
    })
    .inner
}

/// A chart, as bars standing on a shared axis.
///
/// The webview's drawing rather than the terminal's: this renderer paints into
/// a rectangle it asks for, so columns cost it nothing and are what a reader
/// expects of a chart. `makeover-tui` lays its bars down instead, because a
/// terminal has rows to spend and cells to draw with; both are honest answers
/// to the same description and neither is the other's fallback.
///
/// # The axis is the caller's height and the description's maximum
///
/// [`WidgetStyle::chart_height`] says how tall the figure stands and
/// [`Chart::most`] says what a full bar means, which is the same split
/// `--chart-height` and `--most` make in the stylesheet. An axis of zero draws
/// its bars at nothing rather than dividing by it.
///
/// [`Bar::note`] is not painted. There is nowhere to put it without a hover
/// surface this crate does not own, and the reading is the fact worth the room.
pub fn chart(
    ui: &mut Ui,
    chart: &Chart<'_>,
    bars: &[Bar<'_>],
    palette: &Palette,
    style: &WidgetStyle,
) -> Response {
    let width = ui.available_width().max(1.0);
    let (rect, response) =
        ui.allocate_exact_size(Vec2::new(width, style.chart_height), Sense::hover());

    // The places on the axis take a band at the bottom, and the bars stand on
    // top of it. Reserved out of the figure's own height rather than added to
    // it, so `chart_height` is what a caller laying out a screen can measure
    // against -- the same promise `--chart-height` makes in the stylesheet.
    let font = egui::TextStyle::Small.resolve(ui.style());
    let band = ui.text_style_height(&egui::TextStyle::Small);
    let floor = (rect.bottom() - band).max(rect.top());
    let standing = floor - rect.top();

    if bars.is_empty() {
        return response;
    }

    #[expect(
        clippy::cast_precision_loss,
        reason = "a bar count is small and this is a width in points"
    )]
    let each = rect.width() / bars.len() as f32;
    for (index, bar) in bars.iter().enumerate() {
        #[expect(
            clippy::cast_precision_loss,
            reason = "an index into the bars, which are few"
        )]
        let left = rect.left() + each * index as f32;
        let reached = standing * bar.fraction(chart);
        let mut column = egui::Rect::from_min_size(
            egui::Pos2::new(left, floor - reached),
            Vec2::new(each, reached),
        );
        // A bar of nothing still says it is there, which is what the
        // stylesheet's `min-height` does in the other renderer.
        if column.height() < 1.0 {
            column.set_top(floor - 1.0);
        }
        ui.painter()
            .rect_filled(column, style.radius, palette.tone(chart.tone));

        // Centred under the column it belongs to. Drawn by the painter rather
        // than laid out as a row of labels, because a row lays itself out and
        // the labels would then sit where the text put them instead of under
        // their own bars, which is the one thing a place on an axis has to do.
        ui.painter().text(
            egui::Pos2::new(left + each / 2.0, floor),
            egui::Align2::CENTER_TOP,
            bar.at,
            font.clone(),
            palette.content_muted,
        );
    }

    response
}

#[cfg(test)]
mod tests {
    use super::*;

    /// What the accessibility tree says a widget drew.
    fn announced(
        draw: impl FnMut(&mut Ui),
    ) -> Vec<(
        egui::accesskit::Role,
        String,
        Option<egui::accesskit::Toggled>,
    )> {
        let ctx = egui::Context::default();
        ctx.enable_accesskit();
        let mut draw = draw;
        let input = || egui::RawInput {
            screen_rect: Some(egui::Rect::from_min_size(
                egui::Pos2::ZERO,
                egui::vec2(600.0, 400.0),
            )),
            ..Default::default()
        };
        let _ = ctx.run_ui(input(), &mut draw);
        let out = ctx.run_ui(input(), &mut draw);
        out.platform_output
            .accesskit_update
            .expect("accesskit is on")
            .nodes
            .iter()
            .map(|(_, node)| {
                (
                    node.role(),
                    node.label()
                        .or_else(|| node.value())
                        .unwrap_or_default()
                        .to_owned(),
                    node.toggled(),
                )
            })
            .collect()
    }

    #[test]
    fn a_chip_is_announced_as_a_control_and_says_whether_it_is_held() {
        // A token paints its own text onto its own rect, so before 2026-08-22
        // it reached the tree as nothing: pressable by a mouse and invisible to
        // everything else.
        let p = palette();
        let style = WidgetStyle::default();
        let drawn = announced(|ui| {
            token(
                ui,
                "C#",
                Token::Chip { removable: false },
                Tone::Neutral,
                true,
                &p,
                &style,
            );
        });

        let chip = drawn
            .iter()
            .find(|(role, name, _)| *role == egui::accesskit::Role::Button && name == "C#")
            .unwrap_or_else(|| panic!("the chip is not in the tree: {drawn:?}"));
        assert_eq!(
            chip.2,
            Some(egui::accesskit::Toggled::True),
            "a latched chip is held down and says so: {drawn:?}"
        );
    }

    #[test]
    fn a_badge_is_announced_as_the_text_it_is() {
        // Not a control, and not nothing either: a badge is a word on the
        // screen and painting it is not the same as saying it.
        let p = palette();
        let style = WidgetStyle::default();
        let drawn = announced(|ui| {
            token(ui, "wav", Token::Badge, Tone::Neutral, false, &p, &style);
        });

        assert!(
            drawn
                .iter()
                .any(|(role, name, _)| *role == egui::accesskit::Role::Label && name == "wav"),
            "{drawn:?}"
        );
        assert!(
            !drawn
                .iter()
                .any(|(role, _, _)| *role == egui::accesskit::Role::Button),
            "a badge answers nothing and must not claim to: {drawn:?}"
        );
    }

    fn palette() -> Palette {
        use egui::Color32;
        Palette {
            page: Color32::from_rgb(1, 1, 1),
            raised: Color32::from_rgb(2, 2, 2),
            overlay: Color32::from_rgb(3, 3, 3),
            well: Color32::from_rgb(4, 4, 4),
            sunken: Color32::from_rgb(5, 5, 5),
            bevel_light: Color32::from_rgb(6, 6, 6),
            bevel_dark: Color32::from_rgb(7, 7, 7),
            elevation: Color32::from_black_alpha(40),
            content: Color32::from_rgb(20, 20, 20),
            content_secondary: Color32::from_rgb(120, 120, 120),
            content_muted: Color32::from_rgb(21, 21, 21),
            action: Color32::from_rgb(22, 22, 22),
            danger: Color32::from_rgb(23, 23, 23),
            success: Color32::from_rgb(24, 24, 24),
            warning: Color32::from_rgb(25, 25, 25),
            info: Color32::from_rgb(26, 26, 26),
            border: Color32::from_rgb(200, 200, 200),
            info_surface: Color32::from_rgb(201, 201, 201),
            success_surface: Color32::from_rgb(202, 202, 202),
            warning_surface: Color32::from_rgb(203, 203, 203),
            danger_surface: Color32::from_rgb(204, 204, 204),
            row_stripe: Color32::from_rgb(205, 205, 205),
            row_hover: Color32::from_rgb(206, 206, 206),
            row_rule: Color32::from_rgb(207, 207, 207),
            row_selected: Color32::from_rgb(208, 208, 208),
        }
    }

    #[test]
    fn every_tone_resolves_and_no_two_share_a_colour() {
        // The reason the three status intents arrived together: a resolver
        // missing one has to invent a colour for it.
        let p = palette();
        let all = [
            p.tone(Tone::Neutral),
            p.tone(Tone::Info),
            p.tone(Tone::Success),
            p.tone(Tone::Warning),
            p.tone(Tone::Danger),
        ];
        for (i, a) in all.iter().enumerate() {
            for b in &all[i + 1..] {
                assert_ne!(a, b, "two tones resolved to one colour");
            }
        }
        assert_eq!(p.tone(Tone::Neutral), p.content, "neutral is ordinary text");
    }

    #[test]
    fn a_meter_draws_and_an_overrun_does_not_panic() {
        // `done` may exceed `total`, which is the case Meter's own docs call
        // the one worth drawing. The fill clamps; the reading does not.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            meter(ui, &Meter::new(3, 6), &p, &style);
            meter(ui, &Meter::new(9, 6), &p, &style);
            // No set, rather than a complete one.
            meter(ui, &Meter::new(0, 0), &p, &style);
            // The overflow `makeover-layout` pins on its own side.
            meter(ui, &Meter::new(u32::MAX, u32::MAX), &p, &style);
        });
    }

    #[test]
    fn a_wait_draws_a_bar_only_when_something_is_counting_it() {
        // The described total is half of what a bar needs. Without a numerator
        // the honest drawing is the mark, not an empty trough implying that
        // someone is watching bytes land.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            awaiting(
                ui,
                Awaiting::unmeasured(),
                Progress::default(),
                false,
                &p,
                &style,
            );
            awaiting(
                ui,
                Awaiting::of(41_943_040),
                Progress::default(),
                false,
                &p,
                &style,
            );
            awaiting(
                ui,
                Awaiting::of(41_943_040),
                Progress {
                    delivered: Some(10_485_760),
                    elapsed: Some(Duration::from_secs(3)),
                },
                false,
                &p,
                &style,
            );
            // A zero payload is no payload, and over-delivery clamps.
            awaiting(
                ui,
                Awaiting::of(0),
                Progress {
                    delivered: Some(9),
                    elapsed: None,
                },
                false,
                &p,
                &style,
            );
            awaiting(
                ui,
                Awaiting::of(4),
                Progress {
                    delivered: Some(9),
                    elapsed: None,
                },
                false,
                &p,
                &style,
            );
        });
    }

    #[test]
    fn reduced_motion_stills_the_mark_and_does_not_remove_it() {
        // `activity_blink(true)` is None, which means lit and still. A renderer
        // that drew nothing would have answered a request nobody made.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            let still = activity(ui, true, &p, &style);
            let blinking = activity(ui, false, &p, &style);
            assert_eq!(
                still.rect.size(),
                blinking.rect.size(),
                "the mark occupies the same space either way"
            );
        });
    }

    #[test]
    fn a_chip_answers_a_click_and_a_badge_does_not() {
        // `Token::interactive` is the whole difference between the members, and
        // the sense is what makes egui agree with it.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            let badge = token(ui, "beta", Token::Badge, Tone::Info, false, &p, &style);
            assert!(!badge.sense.senses_click(), "a badge answers no click");

            let chip = token(
                ui,
                "drums",
                Token::Chip { removable: false },
                Tone::Neutral,
                false,
                &p,
                &style,
            );
            assert!(chip.sense.senses_click(), "a chip answers a click");
        });
    }

    #[test]
    fn a_disabled_control_is_drawn_and_does_not_answer() {
        // Present, visible, and not answering. Through
        // `State::suppresses_interaction` rather than a second reading here.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            let live = act(ui, &Act::new("Save"), &p, &style);
            assert!(live.enabled());

            let gone = act(ui, &Act::new("Save").state(State::Disabled), &p, &style);
            assert!(!gone.enabled(), "a disabled control still answers");
        });
    }

    #[test]
    fn a_control_shows_the_key_the_description_named() {
        // `Act::key` was written for a terminal before there was one. A desktop
        // app has keys too, so this is its second reader.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            act(ui, &Act::new("New").key("n"), &p, &style);
            act(ui, &Act::new("New"), &p, &style);
        });
    }

    #[test]
    fn a_figure_draws_its_movement_beside_its_value() {
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            figure(ui, &Figure::new("17", "Current streak"), &p, &style);
            figure(
                ui,
                &Figure::new("17", "Current streak")
                    .change("+3")
                    .tone(Tone::Success),
                &p,
                &style,
            );
        });
    }
}