Fix twitchy scrolling on touchpads (#381)

Fix twitchy scrolling on touchpads

include/ALabel.hpp

@@ -36,6 +36,7 @@ class ALabel : public IModule {
 
  private:
   std::vector<int> pid_;
+  gdouble distance_scrolled_;
 };
 
 }  // namespace waybar

include/modules/sway/workspaces.hpp

@@ -41,6 +41,7 @@ class Workspaces : public IModule, public sigc::trackable {
   util::JsonParser                             parser_;
   bool                                         scrolling_;
   std::unordered_map<std::string, Gtk::Button> buttons_;
+  gdouble                                      distance_scrolled_;
 
   util::SleeperThread thread_;
   Ipc                 ipc_;

src/ALabel.cpp

@@ -97,12 +97,24 @@ bool waybar::ALabel::handleScroll(GdkEventScroll* e) {
   }
   if (e->direction == GDK_SCROLL_SMOOTH) {
     gdouble delta_x, delta_y;
-    gdk_event_get_scroll_deltas(reinterpret_cast<const GdkEvent*>(e), &delta_x, &delta_y);
+    gdk_event_get_scroll_deltas(reinterpret_cast<const GdkEvent *>(e), &delta_x, &delta_y);
-    if (delta_y < 0) {
+    distance_scrolled_ += delta_y;
+    gdouble threshold = 0;
+    if (config_["smooth-scrolling-threshold"].isNumeric()) {
+      threshold = config_["smooth-scrolling-threshold"].asDouble();
+    }
+
+    if (distance_scrolled_ < -threshold) {
       direction_up = true;
-    } else if (delta_y > 0) {
+    } else if (distance_scrolled_ > threshold) {
       direction_up = false;
     }
+    if(abs(distance_scrolled_) > threshold) {
+      distance_scrolled_ = 0;
+    } else {
+      // Don't execute the action if we haven't met the threshold!
+      return false;
+    }
   }
   if (direction_up && config_["on-scroll-up"].isString()) {
     pid_.push_back(util::command::forkExec(config_["on-scroll-up"].asString()));

src/modules/sway/workspaces.cpp

@@ -240,24 +240,42 @@ bool Workspaces::handleScroll(GdkEventScroll *e) {
     }
     switch (e->direction) {
       case GDK_SCROLL_DOWN:
-      case GDK_SCROLL_RIGHT:
+      case GDK_SCROLL_RIGHT: {
         name = getCycleWorkspace(it, false);
         break;
+      }
       case GDK_SCROLL_UP:
-      case GDK_SCROLL_LEFT:
+      case GDK_SCROLL_LEFT: {
         name = getCycleWorkspace(it, true);
         break;
-      case GDK_SCROLL_SMOOTH:
+      }
+      case GDK_SCROLL_SMOOTH: {
         gdouble delta_x, delta_y;
         gdk_event_get_scroll_deltas(reinterpret_cast<const GdkEvent *>(e), &delta_x, &delta_y);
-        if (delta_y < 0) {
+
+        if (abs(delta_x) > abs(delta_y)) {
+          distance_scrolled_ += delta_x;
+        } else {
+          distance_scrolled_ += delta_y;
+        }
+        gdouble threshold = 0;
+        if (config_["smooth-scrolling-threshold"].isNumeric()) {
+          threshold = config_["smooth-scrolling-threshold"].asDouble();
+        }
+
+        if (distance_scrolled_ < -threshold) {
           name = getCycleWorkspace(it, true);
-        } else if (delta_y > 0) {
+        } else if (distance_scrolled_ > threshold) {
           name = getCycleWorkspace(it, false);
         }
+        if(abs(distance_scrolled_) > threshold) {
+          distance_scrolled_ = 0;
+        }
         break;
-      default:
+      }
+      default: {
         break;
+      }
     }
     if (name.empty() || name == (*it)["name"].asString()) {
       scrolling_ = false;