Merge PR #799

crates/ui-egui/src/headless.rs

@@ -3357,6 +3357,28 @@ mod tests {
         assert_eq!(h.app.ui.pan, (0.5, 0.5));
     }
 
+    #[test]
+    fn mouse_wheel_zooms_the_loupe_with_and_without_ctrl() {
+        use crate::state::Zoom;
+        let mut h = demo([1000.0, 700.0]);
+        let t = Duration::from_secs(10);
+        h.request("ui.set", json!({"view": "detail", "right": "none", "leftPanel": false, "filmstrip": false}), t);
+        h.settle(SETTLE);
+        for (unit, y, modifiers) in [
+            (egui::MouseWheelUnit::Line, 1.0, egui::Modifiers::NONE),
+            (egui::MouseWheelUnit::Line, 1.0, egui::Modifiers::CTRL),
+            (egui::MouseWheelUnit::Point, 50.0, egui::Modifiers::CTRL),
+        ] {
+            h.request("ui.set", json!({"zoom": "fit", "pan": [0.5, 0.5]}), t);
+            h.request("ui.hoverWidget", json!({"id": "canvas:image"}), t);
+            h.app.synthetic.push(egui::Event::MouseWheel { unit, delta: egui::vec2(0.0, y), phase: egui::TouchPhase::Move, modifiers });
+            for _ in 0..10 {
+                h.step();
+            }
+            assert!(matches!(h.app.ui.zoom, Zoom::Percent(_)), "wheel {unit:?} {modifiers:?} must zoom in, got {:?}", h.app.ui.zoom);
+        }
+    }
+
     #[test]
     fn trackpad_navigation_works_in_tools_compare_reference_and_before_after() {
         use crate::state::Zoom;

crates/ui-egui/src/panels/detail.rs

@@ -153,13 +153,44 @@ pub(crate) fn pan_image(app: &mut LightcraftApp, area: Rect, img: Rect, delta: e
     let _ = app.run("view.navigate", json!({"pan": pan}));
 }
 
+/// Net vertical notches (up is positive) of unmodified line/page-unit wheel events: a real mouse wheel, not a trackpad.
+fn wheel_notches(events: &[egui::Event]) -> f32 {
+    events
+        .iter()
+        .filter_map(|e| match e {
+            egui::Event::MouseWheel { unit: egui::MouseWheelUnit::Line | egui::MouseWheelUnit::Page, delta, modifiers, .. }
+                if *modifiers == egui::Modifiers::NONE && delta.y.is_finite() =>
+            {
+                Some(delta.y)
+            }
+            _ => None,
+        })
+        .sum()
+}
+
 /// Native pinch (also modifier-wheel zoom) and two-finger scroll, scoped to this image view.
 pub(crate) fn navigate_gesture(app: &mut LightcraftApp, ui: &mut egui::Ui, resp: &egui::Response, area: Rect, img: Rect, native: [usize; 2]) -> bool {
     if !resp.hovered() {
         return false;
     }
-    let (factor, delta, anchor) =
+    let (mut factor, mut delta, anchor) =
         ui.input(|i| (i.zoom_delta(), i.translation_delta(), i.multi_touch().map(|t| t.center_pos).or(i.pointer.hover_pos())));
+    // A notched mouse wheel (line/page units, no modifier) zooms around the pointer, through egui's smoothed wheel
+    // delta like Ctrl+wheel (so it glides instead of jumping); trackpads report points and still pan.
+    let wheel_id = egui::Id::new("loupe-wheel-zoom");
+    if ui.input(|i| wheel_notches(&i.events)) != 0.0 {
+        ui.data_mut(|d| d.insert_temp(wheel_id, true));
+    }
+    if ui.data(|d| d.get_temp::<bool>(wheel_id)).unwrap_or(false) {
+        let smooth = ui.input(|i| i.smooth_scroll_delta.y);
+        let speed = ui.ctx().options(|o| o.input_options.scroll_zoom_speed);
+        if smooth == 0.0 {
+            ui.data_mut(|d| d.remove_temp::<bool>(wheel_id));
+        } else {
+            factor *= (speed * smooth).exp();
+            delta = egui::Vec2::ZERO;
+        }
+    }
     if !factor.is_finite() || factor <= 0.0 || !delta.is_finite() || (factor == 1.0 && delta == egui::Vec2::ZERO) {
         return false;
     }
@@ -2234,3 +2265,21 @@ mod tests {
         assert_eq!(film_label(""), "");
     }
 }
+
+#[cfg(test)]
+mod wheel_zoom_tests {
+    use super::*;
+
+    fn wheel(unit: egui::MouseWheelUnit, y: f32, modifiers: egui::Modifiers) -> egui::Event {
+        egui::Event::MouseWheel { unit, delta: egui::vec2(0.0, y), phase: egui::TouchPhase::Move, modifiers }
+    }
+
+    #[test]
+    fn only_notched_unmodified_wheels_count() {
+        let m = egui::Modifiers::NONE;
+        assert_eq!(wheel_notches(&[wheel(egui::MouseWheelUnit::Line, 1.0, m), wheel(egui::MouseWheelUnit::Line, 2.0, m)]), 3.0);
+        assert_eq!(wheel_notches(&[wheel(egui::MouseWheelUnit::Point, 40.0, m)]), 0.0);
+        assert_eq!(wheel_notches(&[wheel(egui::MouseWheelUnit::Line, 1.0, egui::Modifiers::CTRL)]), 0.0);
+        assert_eq!(wheel_notches(&[wheel(egui::MouseWheelUnit::Line, f32::NAN, m)]), 0.0);
+    }
+}