From 8792089752f1c8341f31d18e5602c6da2ff0d289 Mon Sep 17 00:00:00 2001
From: Michael Herzberg <michael@mherzberg.de>
Date: Sat, 23 Feb 2019 17:37:11 +0000
Subject: [PATCH] Ignore first pair of coordinates, which are occasionally far
 off.

---
 src/io/input.cpp | 12 ++++++++----
 src/io/input.h   |  2 ++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/io/input.cpp b/src/io/input.cpp
index 943dc96..62929d1 100644
--- a/src/io/input.cpp
+++ b/src/io/input.cpp
@@ -54,8 +54,8 @@ void gebaar::io::Input::handle_swipe_event_without_coords(libinput_event_gesture
 {
     if (begin) {
         gesture_swipe_event.fingers = libinput_event_gesture_get_finger_count(gev);
-    }
-    else {
+        has_received_updates = false;
+    } else {
         double x = gesture_swipe_event.x;
         double y = gesture_swipe_event.y;
         int swipe_type = 5; // middle = no swipe
@@ -99,8 +99,12 @@ void gebaar::io::Input::handle_swipe_event_without_coords(libinput_event_gesture
  */
 void gebaar::io::Input::handle_swipe_event_with_coords(libinput_event_gesture* gev)
 {
-    gesture_swipe_event.x += libinput_event_gesture_get_dx(gev);
-    gesture_swipe_event.y += libinput_event_gesture_get_dy(gev);
+    if (has_received_updates) {
+        gesture_swipe_event.x += libinput_event_gesture_get_dx(gev);
+        gesture_swipe_event.y += libinput_event_gesture_get_dy(gev);
+    } else {
+        has_received_updates = true;
+    }
 }
 
 /**
diff --git a/src/io/input.h b/src/io/input.h
index b40d61f..f7299c2 100644
--- a/src/io/input.h
+++ b/src/io/input.h
@@ -44,6 +44,8 @@ namespace gebaar::io {
     private:
         std::shared_ptr<gebaar::config::Config> config;
 
+        bool has_received_updates;
+
         struct libinput* libinput;
         struct libinput_event* libinput_event;
         struct udev* udev;