Painter extend accepts IntoIter (#2249)

* `Painter` extend accepts `IntoIter`

* Update painter.rs

crates/egui/src/layers.rs

@@ -130,9 +130,12 @@ impl PaintList {
         idx
     }
 
-    pub fn extend(&mut self, clip_rect: Rect, mut shapes: Vec<Shape>) {
-        self.0
-            .extend(shapes.drain(..).map(|shape| ClippedShape(clip_rect, shape)));
+    pub fn extend<I: IntoIterator<Item = Shape>>(&mut self, clip_rect: Rect, shapes: I) {
+        self.0.extend(
+            shapes
+                .into_iter()
+                .map(|shape| ClippedShape(clip_rect, shape)),
+        );
     }
 
     /// Modify an existing [`Shape`].

crates/egui/src/painter.rs

@@ -178,19 +178,19 @@ impl Painter {
     /// Add many shapes at once.
     ///
     /// Calling this once is generally faster than calling [`Self::add`] multiple times.
-    pub fn extend(&self, mut shapes: Vec<Shape>) {
+    pub fn extend<I: IntoIterator<Item = Shape>>(&self, shapes: I) {
         if self.fade_to_color == Some(Color32::TRANSPARENT) {
             return;
         }
-        if !shapes.is_empty() {
-            if self.fade_to_color.is_some() {
-                for shape in &mut shapes {
-                    self.transform_shape(shape);
-                }
-            }
-
+        if self.fade_to_color.is_some() {
+            let shapes = shapes.into_iter().map(|mut shape| {
+                self.transform_shape(&mut shape);
+                shape
+            });
             self.paint_list().extend(self.clip_rect, shapes);
-        }
+        } else {
+            self.paint_list().extend(self.clip_rect, shapes);
+        };
     }
 
     /// Modify an existing [`Shape`].

crates/egui_demo_lib/src/demo/paint_bezier.rs

@@ -77,28 +77,28 @@ impl PaintBezier {
 
         let control_point_radius = 8.0;
 
-        let mut control_point_shapes = vec![];
+        let control_point_shapes: Vec<Shape> = self
+            .control_points
+            .iter_mut()
+            .enumerate()
+            .take(self.degree)
+            .map(|(i, point)| {
+                let size = Vec2::splat(2.0 * control_point_radius);
 
-        for (i, point) in self.control_points.iter_mut().enumerate().take(self.degree) {
-            let size = Vec2::splat(2.0 * control_point_radius);
+                let point_in_screen = to_screen.transform_pos(*point);
+                let point_rect = Rect::from_center_size(point_in_screen, size);
+                let point_id = response.id.with(i);
+                let point_response = ui.interact(point_rect, point_id, Sense::drag());
 
-            let point_in_screen = to_screen.transform_pos(*point);
-            let point_rect = Rect::from_center_size(point_in_screen, size);
-            let point_id = response.id.with(i);
-            let point_response = ui.interact(point_rect, point_id, Sense::drag());
+                *point += point_response.drag_delta();
+                *point = to_screen.from().clamp(*point);
 
-            *point += point_response.drag_delta();
-            *point = to_screen.from().clamp(*point);
+                let point_in_screen = to_screen.transform_pos(*point);
+                let stroke = ui.style().interact(&point_response).fg_stroke;
 
-            let point_in_screen = to_screen.transform_pos(*point);
-            let stroke = ui.style().interact(&point_response).fg_stroke;
-
-            control_point_shapes.push(Shape::circle_stroke(
-                point_in_screen,
-                control_point_radius,
-                stroke,
-            ));
-        }
+                Shape::circle_stroke(point_in_screen, control_point_radius, stroke)
+            })
+            .collect();
 
         let points_in_screen: Vec<Pos2> = self
             .control_points

crates/egui_demo_lib/src/demo/painting.rs

@@ -56,13 +56,15 @@ impl Painting {
             response.mark_changed();
         }
 
-        let mut shapes = vec![];
-        for line in &self.lines {
-            if line.len() >= 2 {
+        let shapes = self
+            .lines
+            .iter()
+            .filter(|line| line.len() >= 2)
+            .map(|line| {
                 let points: Vec<Pos2> = line.iter().map(|p| to_screen * *p).collect();
-                shapes.push(egui::Shape::line(points, self.stroke));
-            }
-        }
+                egui::Shape::line(points, self.stroke)
+            });
+
         painter.extend(shapes);
 
         response