Simplify arc drawing

crates/egui/src/widgets/theme_switch/arc.rs

@@ -1,51 +1,26 @@
-use crate::{vec2, Color32, Painter, Pos2, Shape, Stroke, Vec2};
-use epaint::CubicBezierShape;
+use emath::{vec2, Pos2, Vec2};
+use epaint::{Color32, CubicBezierShape, Stroke};
 use std::f32::consts::FRAC_PI_2;
 use std::ops::RangeInclusive;
 
-#[derive(Debug, Clone, PartialEq)]
-pub struct ArcShape {
-    center: Pos2,
-    radius: f32,
-    range: RangeInclusive<f32>,
-    fill: Color32,
-    stroke: Stroke,
-}
-
-impl ArcShape {
-    pub fn new(
-        center: impl Into<Pos2>,
-        radius: impl Into<f32>,
-        range: impl Into<RangeInclusive<f32>>,
-        fill: impl Into<Color32>,
-        stroke: impl Into<Stroke>,
-    ) -> Self {
-        Self {
-            center: center.into(),
-            radius: radius.into(),
-            range: range.into(),
-            fill: fill.into(),
-            stroke: stroke.into(),
-        }
-    }
-
-    pub fn approximate_as_beziers(&self) -> impl Iterator<Item = CubicBezierShape> + Clone {
-        let fill = self.fill;
-        let stroke = self.stroke;
-        approximate_with_beziers(self.center, self.radius, self.range.clone())
-            .map(move |p| CubicBezierShape::from_points_stroke(p, false, fill, stroke))
-    }
-
-    pub fn paint(&self, painter: &Painter) {
-        painter.extend(self.approximate_as_beziers().map(Shape::from));
-    }
+pub(crate) fn approximate_with_beziers(
+    center: impl Into<Pos2>,
+    radius: impl Into<f32>,
+    range: impl Into<RangeInclusive<f32>>,
+    fill: impl Into<Color32>,
+    stroke: impl Into<Stroke>,
+) -> impl Iterator<Item = CubicBezierShape> + Clone {
+    let fill = fill.into();
+    let stroke = stroke.into();
+    approximate_with_beziers_impl(center.into(), radius.into(), range.into())
+        .map(move |p| CubicBezierShape::from_points_stroke(p, false, fill, stroke))
 }
 
 // Implementation based on:
 // Riškus, Aleksas. (2006). Approximation of a cubic bezier curve by circular arcs and vice versa.
 // Information Technology and Control. 35.
 
-fn approximate_with_beziers(
+fn approximate_with_beziers_impl(
     center: Pos2,
     radius: f32,
     range: RangeInclusive<f32>,

crates/egui/src/widgets/theme_switch/mod.rs

@@ -23,6 +23,8 @@ impl<'a> ThemeSwitch<'a> {
         }
     }
 
+    /// Disables the "Follow System" option. Intentionally internal.
+    /// Should be removed once https://github.com/emilk/egui/issues/4490 is done.
     pub(crate) fn show_follow_system(mut self, show_follow_system: bool) -> Self {
         self.show_follow_system = show_follow_system;
         self

crates/egui/src/widgets/theme_switch/moon.rs

@@ -1,4 +1,4 @@
-use super::arc::ArcShape;
+use super::arc;
 use crate::epaint::{CubicBezierShape, PathShape, PathStroke};
 use crate::{Color32, Painter, Pos2, Vec2};
 use std::f32::consts::{PI, TAU};
@@ -27,14 +27,14 @@ pub(crate) fn moon(painter: &Painter, center: Pos2, radius: f32, color: Color32)
     let occlusion_start = direction_angle + PI - angle / 2.;
     let occlusion_end = direction_angle + PI + angle / 2.;
 
-    let main_arc = ArcShape::new(
+    let main_arc = arc::approximate_with_beziers(
         center,
         radius,
         start..=(start + size),
         Color32::TRANSPARENT,
         (stroke_width, color),
     );
-    let occluding_arc = ArcShape::new(
+    let occluding_arc = arc::approximate_with_beziers(
         occluding_center,
         radius,
         occlusion_end..=occlusion_start,
@@ -44,12 +44,7 @@ pub(crate) fn moon(painter: &Painter, center: Pos2, radius: f32, color: Color32)
 
     // We join the beziers together to a path which improves
     // the drawing of the joints somewhat.
-    let path = to_path(
-        main_arc
-            .approximate_as_beziers()
-            .chain(occluding_arc.approximate_as_beziers()),
-        (stroke_width, color),
-    );
+    let path = to_path(main_arc.chain(occluding_arc), (stroke_width, color));
 
     painter.add(path);
 }