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//! Determinate circular progress indicator.
//!
//! A ring-shaped cousin of [`ProgressBar`](crate::ProgressBar): a faint
//! track plus an accent-coloured arc that sweeps clockwise from 12
//! o'clock as the fraction grows. Centre text defaults to a rounded
//! percent; pass an explicit label via [`ProgressRing::text`] or add a
//! small sub-caption with [`ProgressRing::caption`].
//!
//! For *indeterminate* "still working" loaders, prefer
//! [`Spinner`](crate::Spinner). This widget renders a fixed fraction
//! each frame and never requests repaints on its own.
use std::f32::consts::{PI, TAU};
use egui::{
epaint::{PathShape, PathStroke},
pos2, Color32, Pos2, Response, Sense, Ui, Vec2, Widget, WidgetInfo, WidgetType,
};
use crate::theme::{Accent, Theme};
/// A themed determinate circular progress indicator.
///
/// ```no_run
/// # use elegance::{Accent, ProgressRing};
/// # egui::__run_test_ui(|ui| {
/// // Default: 56 pt diameter, sky arc, percent in the centre.
/// ui.add(ProgressRing::new(0.42));
///
/// // Larger, green, custom centre text + sub-caption.
/// ui.add(
/// ProgressRing::new(0.6)
/// .size(88.0)
/// .accent(Accent::Green)
/// .text("12 / 20")
/// .caption("files"),
/// );
///
/// // Hide the centre text entirely with an empty override.
/// ui.add(ProgressRing::new(0.3).size(32.0).text(""));
/// # });
/// ```
#[derive(Debug, Clone)]
#[must_use = "Add with `ui.add(...)`."]
pub struct ProgressRing {
fraction: f32,
size: f32,
stroke_width: Option<f32>,
color: Option<Color32>,
accent: Option<Accent>,
text: Option<String>,
caption: Option<String>,
}
impl ProgressRing {
/// Create a ring at `fraction` (0..=1). NaN and out-of-range values
/// are clamped.
pub fn new(fraction: f32) -> Self {
Self {
fraction: if fraction.is_nan() {
0.0
} else {
fraction.clamp(0.0, 1.0)
},
size: 56.0,
stroke_width: None,
color: None,
accent: None,
text: None,
caption: None,
}
}
/// Outer diameter in points. Default: 56. Clamped to at least 8.
#[inline]
pub fn size(mut self, size: f32) -> Self {
self.size = size.max(8.0);
self
}
/// Arc stroke thickness in points. Defaults to ~8 % of `size`,
/// clamped to `[3.0, 10.0]`.
#[inline]
pub fn stroke_width(mut self, width: f32) -> Self {
self.stroke_width = Some(width.max(1.0));
self
}
/// Paint the arc with an explicit colour. Clears any previously set
/// accent.
pub fn color(mut self, color: Color32) -> Self {
self.color = Some(color);
self.accent = None;
self
}
/// Pick the arc colour from one of the theme's accents. Clears any
/// previously set explicit colour. Default: the theme's sky.
pub fn accent(mut self, accent: Accent) -> Self {
self.accent = Some(accent);
self.color = None;
self
}
/// Override the centre text. By default the ring shows the rounded
/// percent (e.g. "42%") once `size >= 40`; passing `""` hides the
/// text entirely.
pub fn text(mut self, text: impl Into<String>) -> Self {
self.text = Some(text.into());
self
}
/// Add a small muted sub-caption below the primary text.
pub fn caption(mut self, caption: impl Into<String>) -> Self {
self.caption = Some(caption.into());
self
}
}
impl Widget for ProgressRing {
fn ui(self, ui: &mut Ui) -> Response {
let theme = Theme::current(ui.ctx());
let p = &theme.palette;
let color = match (self.color, self.accent) {
(Some(c), _) => c,
(_, Some(a)) => p.accent_fill(a),
_ => p.sky,
};
let stroke_w = self
.stroke_width
.unwrap_or((self.size * 0.08).clamp(3.0, 10.0));
let (rect, response) = ui.allocate_exact_size(Vec2::splat(self.size), Sense::hover());
if ui.is_rect_visible(rect) {
let painter = ui.painter();
let center = rect.center();
// Subtract half-stroke so the ring's outer edge lands on the
// allocated rect; extra 1 pt keeps anti-aliased edges clean.
let radius = ((self.size * 0.5) - stroke_w * 0.5 - 1.0).max(0.5);
let track_color = p.depth_tint(p.card, 0.1);
// Track and arc share the same sample density + PathShape
// primitive so they sit on identical pixels; mixing
// `circle_stroke` (internal tessellation) with a manual
// `PathShape::line` (polyline) produces a subtle concentric
// mismatch.
let n_full: usize = 96;
let point_at = |a: f32| {
let (sin, cos) = a.sin_cos();
pos2(center.x + radius * cos, center.y + radius * sin)
};
let track_points: Vec<Pos2> = (0..n_full)
.map(|i| point_at((i as f32 / n_full as f32) * TAU))
.collect();
painter.add(PathShape::closed_line(
track_points,
PathStroke::new(stroke_w, track_color),
));
// Arc, clockwise from 12 o'clock.
if self.fraction > 0.0 {
let sweep = TAU * self.fraction;
let start = -PI * 0.5;
// Match the track's per-radian sampling so the arc
// points lie exactly on the same polygon vertices.
let n_points = ((n_full as f32 * self.fraction).ceil() as usize).max(2);
let points: Vec<Pos2> = (0..=n_points)
.map(|i| point_at(start + sweep * (i as f32 / n_points as f32)))
.collect();
// Rounded endpoint caps — PathShape strokes are butt-ended.
painter.circle_filled(points[0], stroke_w * 0.5, color);
painter.circle_filled(points[n_points], stroke_w * 0.5, color);
painter.add(PathShape::line(points, PathStroke::new(stroke_w, color)));
}
// Centre label + caption.
let primary: String = match &self.text {
Some(s) => s.clone(),
None if self.size >= 40.0 => {
format!("{}%", (self.fraction * 100.0).round() as u32)
}
_ => String::new(),
};
let caption = self.caption.as_deref().unwrap_or("");
let primary_size = (self.size * 0.20).clamp(10.0, 24.0);
let caption_size = (self.size * 0.11).clamp(8.0, 12.0);
let primary_galley = (!primary.is_empty()).then(|| {
crate::theme::placeholder_galley(ui, &primary, primary_size, true, f32::INFINITY)
});
let caption_galley = (!caption.is_empty()).then(|| {
crate::theme::placeholder_galley(ui, caption, caption_size, false, f32::INFINITY)
});
let primary_h = primary_galley.as_ref().map_or(0.0, |g| g.size().y);
let caption_h = caption_galley.as_ref().map_or(0.0, |g| g.size().y);
let line_gap = if primary_galley.is_some() && caption_galley.is_some() {
2.0
} else {
0.0
};
let group_h = primary_h + line_gap + caption_h;
let top_y = center.y - group_h * 0.5;
if let Some(g) = primary_galley {
let g_w = g.size().x;
painter.galley(pos2(center.x - g_w * 0.5, top_y), g, p.text);
}
if let Some(g) = caption_galley {
let g_w = g.size().x;
let y = top_y + primary_h + line_gap;
painter.galley(pos2(center.x - g_w * 0.5, y), g, p.text_muted);
}
}
response
.widget_info(|| WidgetInfo::labeled(WidgetType::ProgressIndicator, true, "progress"));
response
}
}