rotation feature to plot images (#3121)

crates/egui/src/widgets/plot/items/mod.rs

@@ -1132,6 +1132,7 @@ pub struct PlotImage {
     pub(super) tint: Color32,
     pub(super) highlight: bool,
     pub(super) name: String,
+    pub(crate) rotation: Option<(f32, Vec2)>,
 }
 
 impl PlotImage {
@@ -1150,6 +1151,7 @@ impl PlotImage {
             size: size.into(),
             bg_fill: Default::default(),
             tint: Color32::WHITE,
+            rotation: None,
         }
     }
 
@@ -1188,6 +1190,17 @@ impl PlotImage {
         self.name = name.to_string();
         self
     }
+
+    /// Rotate the image about an origin by some angle
+    ///
+    /// Positive angle is clockwise.
+    /// Origin is a vector in normalized UV space ((0,0) in top-left, (1,1) bottom right).
+    ///
+    /// To rotate about the center you can pass `Vec2::splat(0.5)` as the origin.
+    pub fn rotate(mut self, angle: f32, origin: Vec2) -> Self {
+        self.rotation = Some((angle, origin));
+        self
+    }
 }
 
 impl PlotItem for PlotImage {
@@ -1215,11 +1228,14 @@ impl PlotItem for PlotImage {
             let right_bottom_tf = transform.position_from_point(&right_bottom);
             Rect::from_two_pos(left_top_tf, right_bottom_tf)
         };
-        Image::new(*texture_id, *size)
+        let mut image = Image::new(*texture_id, *size)
             .bg_fill(*bg_fill)
             .tint(*tint)
-            .uv(*uv)
+            .uv(*uv);
-            .paint_at(ui, rect);
+        if let Some((angle, origin)) = self.rotation {
+            image = image.rotate(angle, origin);
+        }
+        image.paint_at(ui, rect);
         if *highlight {
             shapes.push(Shape::rect_stroke(
                 rect,