From ed4521d1138cc3d9a660d8e7fac840fd2867cd53 Mon Sep 17 00:00:00 2001
From: Patrick Hilhorst <git@hilhorst.be>
Date: Tue, 11 Jun 2019 16:19:11 +0200
Subject: [PATCH] Workspaces: fix twitchy scrolling on touchpads

Previously, any and all scroll events were interpreted as reason to switch
workspaces. This resulted in twitchy behaviour, where the scrolling was
practically unusable.

Now, we pool all scroll values, and only scroll if the value is larger than the
new config option "smooth-scrolling-threshold". If this option is not set, the
behaviour is unchanged.
---
 include/modules/sway/workspaces.hpp |  1 +
 src/modules/sway/workspaces.cpp     | 25 +++++++++++++++++++------
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/include/modules/sway/workspaces.hpp b/include/modules/sway/workspaces.hpp
index b7632de1..33789df4 100644
--- a/include/modules/sway/workspaces.hpp
+++ b/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_;
diff --git a/src/modules/sway/workspaces.cpp b/src/modules/sway/workspaces.cpp
index 94a5e03e..3da550e8 100644
--- a/src/modules/sway/workspaces.cpp
+++ b/src/modules/sway/workspaces.cpp
@@ -234,24 +234,37 @@ 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) {
+        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;