From 4f6c547e476fd822d22a9634be6d010408796f8c Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Fri, 26 Feb 2016 14:43:20 -0500
Subject: [PATCH] Fix scrolling behavior by accumulating partial ticks

---
 input.cpp     | 15 +++++++++++++--
 moonlight.hpp |  4 +++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/input.cpp b/input.cpp
index abb33da..e9ca6bc 100644
--- a/input.cpp
+++ b/input.cpp
@@ -112,14 +112,25 @@ bool MoonlightInstance::HandleInputEvent(const pp::InputEvent& event) {
         }
         
         case PP_INPUTEVENT_TYPE_WHEEL: {
+            signed char fullTicks;
+            
             if (!m_MouseLocked) {
                 return false;
             }
             
             pp::WheelInputEvent wheelEvent(event);
             
-            // FIXME: Handle fractional scroll ticks
-            LiSendScrollEvent((signed char) wheelEvent.GetTicks().y());
+            // Accumulate the current tick value
+            m_AccumulatedTicks += wheelEvent.GetTicks().y();
+            
+            // Compute the number of full ticks
+            fullTicks = (signed char) m_AccumulatedTicks;
+            
+            // Send a scroll event if we've completed a full tick
+            if (fullTicks != 0) {
+                LiSendScrollEvent(fullTicks);
+                m_AccumulatedTicks -= fullTicks;
+            }
             return true;
         }
         
diff --git a/moonlight.hpp b/moonlight.hpp
index e35fd98..386fd09 100644
--- a/moonlight.hpp
+++ b/moonlight.hpp
@@ -44,7 +44,8 @@ class MoonlightInstance : public pp::Instance, public pp::MouseLock {
             m_CallbackFactory(this),
             m_MouseLocked(false),
             m_KeyModifiers(0),
-            m_WaitingForAllModifiersUp(false) {
+            m_WaitingForAllModifiersUp(false),
+            m_AccumulatedTicks(0) {
             // This function MUST be used otherwise sockets don't work (nacl_io_init() doesn't work!)            
             nacl_io_init_ppapi(pp_instance(), pp::Module::Get()->get_browser_interface());
             
@@ -135,6 +136,7 @@ class MoonlightInstance : public pp::Instance, public pp::MouseLock {
         bool m_MouseLocked;
         char m_KeyModifiers;
         bool m_WaitingForAllModifiersUp;
+        float m_AccumulatedTicks;
 };
 
 extern MoonlightInstance* g_Instance;