feat(tray): handle scroll events

include/modules/sni/item.hpp

@@ -70,6 +70,12 @@ class Item : public sigc::trackable {
   static void               onMenuDestroyed(Item* self, GObject* old_menu_pointer);
   void                      makeMenu();
   bool                      handleClick(GdkEventButton* const& /*ev*/);
+  bool                      handleScroll(GdkEventScroll* const&);
+
+  // smooth scrolling threshold
+  gdouble scroll_threshold_ = 0;
+  gdouble distance_scrolled_x_ = 0;
+  gdouble distance_scrolled_y_ = 0;
 
   Glib::RefPtr<Gio::DBus::Proxy> proxy_;
   Glib::RefPtr<Gio::Cancellable> cancellable_;

man/waybar-tray.5.scd

@@ -16,6 +16,10 @@ Addressed by *tray*
     typeof: integer ++
     Defines the size of the tray icons.
 
+*smooth-scrolling-threshold*: ++
+	typeof: double ++
+	Threshold to be used when scrolling.
+
 *spacing*: ++
     typeof: integer ++
     Defines the spacing between the tray icons.

src/modules/sni/item.cpp

@@ -48,9 +48,13 @@ Item::Item(const std::string& bn, const std::string& op, const Json::Value& conf
   if (config["icon-size"].isUInt()) {
     icon_size = config["icon-size"].asUInt();
   }
+  if (config["smooth-scrolling-threshold"].isNumeric()) {
+    scroll_threshold_ = config["smooth-scrolling-threshold"].asDouble();
+  }
   event_box.add(image);
-  event_box.add_events(Gdk::BUTTON_PRESS_MASK);
+  event_box.add_events(Gdk::BUTTON_PRESS_MASK | Gdk::SCROLL_MASK | Gdk::SMOOTH_SCROLL_MASK);
   event_box.signal_button_press_event().connect(sigc::mem_fun(*this, &Item::handleClick));
+  event_box.signal_scroll_event().connect(sigc::mem_fun(*this, &Item::handleScroll));
 
   cancellable_ = Gio::Cancellable::create();
 
@@ -403,4 +407,52 @@ bool Item::handleClick(GdkEventButton* const& ev) {
   return false;
 }
 
+bool Item::handleScroll(GdkEventScroll* const& ev) {
+  int dx = 0, dy = 0;
+  switch (ev->direction) {
+    case GDK_SCROLL_UP:
+      dy = -1;
+      break;
+    case GDK_SCROLL_DOWN:
+      dy = 1;
+      break;
+    case GDK_SCROLL_LEFT:
+      dx = -1;
+      break;
+    case GDK_SCROLL_RIGHT:
+      dx = 1;
+      break;
+    case GDK_SCROLL_SMOOTH:
+      distance_scrolled_x_ += ev->delta_x;
+      distance_scrolled_y_ += ev->delta_y;
+      // check against the configured threshold and ensure that the absolute value >= 1
+      if (distance_scrolled_x_ > scroll_threshold_) {
+        dx = (int)lround(std::max(distance_scrolled_x_, 1.0));
+        distance_scrolled_x_ = 0;
+      } else if (distance_scrolled_x_ < -scroll_threshold_) {
+        dx = (int)lround(std::min(distance_scrolled_x_, -1.0));
+        distance_scrolled_x_ = 0;
+      }
+      if (distance_scrolled_y_ > scroll_threshold_) {
+        dy = (int)lround(std::max(distance_scrolled_y_, 1.0));
+        distance_scrolled_y_ = 0;
+      } else if (distance_scrolled_y_ < -scroll_threshold_) {
+        dy = (int)lround(std::min(distance_scrolled_y_, -1.0));
+        distance_scrolled_y_ = 0;
+      }
+      break;
+  }
+  if (dx != 0) {
+    auto parameters = Glib::VariantContainerBase::create_tuple(
+        {Glib::Variant<int>::create(dx), Glib::Variant<Glib::ustring>::create("horizontal")});
+    proxy_->call("Scroll", parameters);
+  }
+  if (dy != 0) {
+    auto parameters = Glib::VariantContainerBase::create_tuple(
+        {Glib::Variant<int>::create(dy), Glib::Variant<Glib::ustring>::create("vertical")});
+    proxy_->call("Scroll", parameters);
+  }
+  return true;
+}
+
 }  // namespace waybar::modules::SNI