added support for using scroll wheel to modify knob value

examples/example_knob.rs

@@ -88,7 +88,8 @@ impl eframe::App for KnobDemo {
                                 .with_show_filled_segments(self.show_filled)
                                 .with_colors(self.knob_color, self.line_color, self.text_color)
                                 .with_step(self.use_step.then_some(0.02))
-                                .with_double_click_reset(0.5);
+                                .with_double_click_reset(0.5)
+                                .with_middle_scroll();
 
                             if *label == "Wiper, Sweep" {
                                 knob = knob.with_sweep_range(0.25, 0.75).with_size(50.0);

src/config.rs

@@ -17,6 +17,7 @@ pub struct KnobConfig {
     pub(crate) min_angle: f32,
     pub(crate) max_angle: f32,
     pub(crate) reset_value: Option<f32>,
+    pub(crate) allow_scroll: bool,
 }
 
 impl KnobConfig {
@@ -38,6 +39,7 @@ impl KnobConfig {
             show_background_arc: true,
             show_filled_segments: true,
             reset_value: None,
+            allow_scroll:false
         }
     }
 }

src/widget.rs

@@ -161,6 +161,13 @@ impl<'a> Knob<'a> {
         self.config.reset_value = Some(reset_value);
         self
     }
+
+    /// Allows user to use scroll wheel to change knob value
+    /// Uses config.step for the increment value
+    pub fn with_middle_scroll(mut self) -> Self {
+        self.config.allow_scroll = true;
+        self
+    }
 }
 
 impl Widget for Knob<'_> {
@@ -198,6 +205,17 @@ impl Widget for Knob<'_> {
             if let Some(reset_value) = self.config.reset_value {
                 *self.value = reset_value
             }
+        } else if response.hovered() & self.config.allow_scroll {
+            if let Some(scoll) = ui.input(|input| {
+                input.events.iter().find_map(|e| match e {
+                    egui::Event::MouseWheel { delta, .. } => Some(*delta),
+                    _ => None,
+                })
+            }) {
+                *self.value = (*self.value
+                    + scoll.y * self.config.step.unwrap_or(self.config.drag_sensitivity))
+                .clamp(self.min, self.max);
+            }
         }
 
         let knob_rect = renderer.calculate_knob_rect(rect);