From 9a71b4c237c0885a6cfc8be4db84f192e1c58b08 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Tue, 4 Sep 2018 00:09:35 -0700
Subject: [PATCH] Improve mouse batching to only batch if the last event was
 less than 1 millisecond ago

---
 app/streaming/input.cpp | 17 +++++++++++++----
 app/streaming/input.hpp |  1 +
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/app/streaming/input.cpp b/app/streaming/input.cpp
index 9977041b..877858a0 100644
--- a/app/streaming/input.cpp
+++ b/app/streaming/input.cpp
@@ -23,7 +23,8 @@ const int SdlInputHandler::k_ButtonMap[] = {
 };
 
 SdlInputHandler::SdlInputHandler(bool multiController)
-    : m_MultiController(multiController)
+    : m_LastMouseMotionTime(0),
+      m_MultiController(multiController)
 {
     // Allow gamepad input when the app doesn't have focus
     SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "1");
@@ -391,11 +392,19 @@ void SdlInputHandler::handleMouseMotionEvent(SDL_MouseMotionEvent* event)
     short xdelta = (short)event->xrel;
     short ydelta = (short)event->yrel;
 
-    // Delay for 1 ms to allow batching of mouse move
-    // events from high DPI mice.
-    SDL_Delay(1);
+    // If we're sending more than one motion event per millisecond,
+    // delay for 1 ms to allow batching of mouse move events.
+    Uint32 currentTime = SDL_GetTicks();
+    if (!SDL_TICKS_PASSED(currentTime, m_LastMouseMotionTime + 1)) {
+        SDL_Delay(1);
+        currentTime = SDL_GetTicks();
+    }
+    m_LastMouseMotionTime = currentTime;
+
+    // Pump even if we didn't delay since we might get some extra events
     SDL_PumpEvents();
 
+    // Batch all of the pending mouse motion events
     SDL_Event nextEvent;
     while (SDL_PeepEvents(&nextEvent,
                           1,
diff --git a/app/streaming/input.hpp b/app/streaming/input.hpp
index 5a9991df..db040a02 100644
--- a/app/streaming/input.hpp
+++ b/app/streaming/input.hpp
@@ -44,6 +44,7 @@ private:
 
     void sendGamepadState(GamepadState* state);
 
+    Uint32 m_LastMouseMotionTime;
     bool m_MultiController;
     int m_GamepadMask;
     GamepadState m_GamepadState[MAX_GAMEPADS];