Manually rotate rect

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

@@ -1,7 +1,7 @@
-use super::painter_ext::PainterExt;
+use super::rotated_rect::draw_rotated_rect;
 use crate::Painter;
 use emath::{vec2, Pos2, Rect, Rot2};
-use epaint::{Color32, RectShape, Rounding};
+use epaint::{Color32, Rounding};
 use std::f32::consts::TAU;
 
 pub(crate) fn cogwheel(painter: &Painter, center: Pos2, radius: f32, color: Color32) {
@@ -24,15 +24,13 @@ pub(crate) fn cogwheel(painter: &Painter, center: Pos2, radius: f32, color: Colo
     for n in 0..cogs {
         let cog_center = center - vec2(0., outer_radius + cog_length / 2. - thickness / 2.);
         let cog_size = vec2(cog_width, cog_length);
-        let cog = RectShape::filled(
-            Rect::from_center_size(cog_center, cog_size),
-            Rounding {
-                nw: cog_rounding,
-                ne: cog_rounding,
-                ..Default::default()
-            },
-            color,
-        );
-        painter.add_rotated(cog, Rot2::from_angle(TAU / cogs as f32 * n as f32), center);
+        let rotation = Rot2::from_angle(TAU / cogs as f32 * n as f32);
+        let rect = Rect::from_center_size(cog_center, cog_size);
+        let rounding = Rounding {
+            nw: cog_rounding,
+            ne: cog_rounding,
+            ..Default::default()
+        };
+        draw_rotated_rect(painter, rect, rounding, color, rotation, center);
     }
 }

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

@@ -6,7 +6,7 @@ use crate::{Painter, Response, ThemePreference, Ui, Widget};
 mod arc;
 mod cogwheel;
 mod moon;
-mod painter_ext;
+mod rotated_rect;
 mod sun;
 
 #[must_use = "You should put this widget in an ui with `ui.add(widget);`"]

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

@@ -0,0 +1,44 @@
+use crate::Painter;
+use emath::{vec2, Pos2, Rect, Rot2};
+use epaint::{Color32, PathShape, Rounding, Stroke};
+
+/// Draws a rectangle with rounded corners, rotated around an origin.
+pub(crate) fn draw_rotated_rect(
+    painter: &Painter,
+    rect: Rect,
+    rounding: impl Into<Rounding>,
+    fill: impl Into<Color32>,
+    rot: impl Into<Rot2>,
+    origin: Pos2,
+) {
+    let rounding = rounding.into();
+    let fill = fill.into();
+    let rot = rot.into();
+    let safe_inset_points = safe_inset_points(rect, rot, origin, rounding);
+
+    painter.add(PathShape::convex_polygon(
+        safe_inset_points.to_vec(),
+        fill,
+        Stroke::NONE,
+    ));
+
+    // Nobody will notice that we're not actually drawing
+    // the round bits... 🤫
+}
+
+fn safe_inset_points(rect: Rect, rot: Rot2, origin: Pos2, rounding: Rounding) -> [Pos2; 8] {
+    [
+        rotate(rect.left_top() + vec2(0.0, rounding.nw), rot, origin),
+        rotate(rect.left_top() + vec2(rounding.nw, 0.0), rot, origin),
+        rotate(rect.right_top() - vec2(rounding.ne, 0.0), rot, origin),
+        rotate(rect.right_top() + vec2(0.0, rounding.ne), rot, origin),
+        rotate(rect.right_bottom() - vec2(0.0, rounding.se), rot, origin),
+        rotate(rect.right_bottom() - vec2(rounding.se, 0.0), rot, origin),
+        rotate(rect.left_bottom() + vec2(rounding.sw, 0.0), rot, origin),
+        rotate(rect.left_bottom() - vec2(0.0, rounding.sw), rot, origin),
+    ]
+}
+
+fn rotate(point: Pos2, rot: Rot2, origin: Pos2) -> Pos2 {
+    origin + rot * (point - origin)
+}

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

@@ -1,7 +1,7 @@
-use super::painter_ext::PainterExt;
+use super::rotated_rect::draw_rotated_rect;
 use crate::Painter;
 use emath::{vec2, Pos2, Rect, Rot2, Vec2};
-use epaint::{Color32, RectShape, Stroke};
+use epaint::{Color32, Stroke};
 use std::f32::consts::TAU;
 
 pub(crate) fn sun(painter: &Painter, center: Pos2, radius: f32, color: Color32) {
@@ -18,11 +18,8 @@ pub(crate) fn sun(painter: &Painter, center: Pos2, radius: f32, color: Color32)
     for n in 0..rays {
         let ray_center = center - vec2(0., sun_radius + ray_spacing + ray_length / 2.);
         let ray_size = vec2(ray_radius, ray_length);
-        let ray = RectShape::filled(
-            Rect::from_center_size(ray_center, ray_size),
-            ray_radius,
-            color,
-        );
-        clipped.add_rotated(ray, Rot2::from_angle(TAU / rays as f32 * n as f32), center);
+        let rect = Rect::from_center_size(ray_center, ray_size);
+        let rotation = Rot2::from_angle(TAU / rays as f32 * n as f32);
+        draw_rotated_rect(painter, rect, ray_radius / 2.0, color, rotation, center);
     }
 }