Method handle_keyboard_event

src/plot_state.rs:751–788

(
        &mut self,
        event: &keyboard::Event,
        widget: &PlotWidget,
        cursor: mouse::Cursor,
    )

            Event::WheelScrolled { delta } => {
                // Only respond to wheel when cursor is inside our bounds
                let Some(cursor_position) = self.available_cursor_local_position_inside(cursor)
                else {
                    return needs_redraw;
                };

                self.cursor_position = cursor_position;

                let (x, y) = match delta {
                    iced::mouse::ScrollDelta::Lines { x, y } => (x, y),
                    iced::mouse::ScrollDelta::Pixels { x, y } => (x, y),
                };

                match widget.controls.scroll_action(self.modifiers) {
                    Some(ScrollAction::Zoom) => {
                        // Determine zoom axes from modifiers:
                        //   Shift → Y-axis only
                        //   Alt   → X-axis only
                        //   neither → both axes
                        let zoom_x = !self.modifiers.shift();
                        let zoom_y = !self.modifiers.alt();
                        self.zoom_at_cursor(y, viewport, zoom_x, zoom_y);
                        needs_redraw = true;
                    }
                    Some(ScrollAction::Pan) => {
                        let world_pan_x =
                            -x as f64 * (self.camera.half_extents.x / (viewport.x / 2.0));
                        let world_pan_y =
                            y as f64 * (self.camera.half_extents.y / (viewport.y / 2.0));
                        self.camera.position.x += world_pan_x;
                        self.camera.position.y += world_pan_y;
                        self.update_axis_links();
                        needs_redraw = true;
                    }
                    _ => {}
                }
            }
            _ => {}
        }

        // camera uniform is handled in renderer per frame
        needs_redraw