From 35873afc9911efb8148e0ed4d18cd1782e2f5b54 Mon Sep 17 00:00:00 2001
From: joncruz <joncruz@users.sourceforge.net>
Date: Sat, 26 Jul 2008 08:08:33 +0000
Subject: [PATCH] Added compensation factor for time-skew with event latency.

---
 src/debug/gdk-event-latency-tracker.cpp | 6 ++++--
 src/debug/gdk-event-latency-tracker.h   | 1 +
 src/preferences-skeleton.h              | 3 +++
 src/ui/dialog/inkscape-preferences.cpp  | 5 +++++
 src/ui/dialog/inkscape-preferences.h    | 1 +
 5 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/debug/gdk-event-latency-tracker.cpp b/src/debug/gdk-event-latency-tracker.cpp
index 8e34d2fc2..6a8a48eb3 100644
--- a/src/debug/gdk-event-latency-tracker.cpp
+++ b/src/debug/gdk-event-latency-tracker.cpp
@@ -10,12 +10,13 @@
  */
 
 #include "debug/gdk-event-latency-tracker.h"
+#include "prefs-utils.h"
 
 namespace Inkscape {
 namespace Debug {
 
 GdkEventLatencyTracker::GdkEventLatencyTracker()
-: start_seconds(0.0), max_latency(0.0)
+    : start_seconds(0.0), max_latency(0.0), skew(1.0)
 {
     elapsed.stop();
     elapsed.reset();
@@ -31,9 +32,10 @@ boost::optional<double> GdkEventLatencyTracker::process(GdkEvent const *event) {
     if (start_seconds == 0.0) {
         elapsed.start();
         start_seconds = timestamp_seconds;
+        skew = prefs_get_double_attribute_limited("debug.latency", "skew", 1.0, 0.5, 2.0);
         return boost::optional<double>(0.0);
     } else {
-        double const current_seconds = elapsed.elapsed() + start_seconds;
+        double const current_seconds = (elapsed.elapsed() * skew) + start_seconds;
         double delta = current_seconds - timestamp_seconds;
         if (delta < 0.0) {
             start_seconds += -delta;
diff --git a/src/debug/gdk-event-latency-tracker.h b/src/debug/gdk-event-latency-tracker.h
index 8a22fec82..cb04ee035 100644
--- a/src/debug/gdk-event-latency-tracker.h
+++ b/src/debug/gdk-event-latency-tracker.h
@@ -33,6 +33,7 @@ private:
 
     double start_seconds;
     double max_latency;
+    double skew;
     Glib::Timer elapsed;
 };
 
diff --git a/src/preferences-skeleton.h b/src/preferences-skeleton.h
index 9670a4da5..7b762f834 100644
--- a/src/preferences-skeleton.h
+++ b/src/preferences-skeleton.h
@@ -388,6 +388,9 @@ static char const preferences_skeleton[] =
 "    <group id = \"server\" name = \"jabber.org\" port = \"5222\" username = \"\" ssl = \"0\"/>\n"
 "    <group id = \"room\" name = \"inkboard\" server = \"gristle.org\"/>\n"
 "  </group>\n"
+"  <group id=\"debug\">\n"
+"    <group id=\"latency\" skew=\"1\"/>\n"
+"  </group>\n"
 "\n"
 "</inkscape>\n";
 
diff --git a/src/ui/dialog/inkscape-preferences.cpp b/src/ui/dialog/inkscape-preferences.cpp
index 455908a06..1f9ef051e 100644
--- a/src/ui/dialog/inkscape-preferences.cpp
+++ b/src/ui/dialog/inkscape-preferences.cpp
@@ -1049,6 +1049,11 @@ void InkscapePreferences::initPageMisc()
     _page_misc.add_line( false, _("Simplification threshold:"), _misc_simpl, "",
                            _("How strong is the Simplify command by default. If you invoke this command several times in quick succession, it will act more and more aggressively; invoking it again after a pause restores the default threshold."), false);
 
+    _misc_latency_skew.init("debug.latency", "skew", 0.5, 2.0, 0.01, 0.10, 1.0, false, false);
+    _page_misc.add_line( false, _("Latency skew:"), _misc_latency_skew, _("(requires restart)"),
+                           _("Factor by which the event clock is skewed from the actual time (0.9766 on some systems)."), false);
+
+
     this->AddPage(_page_misc, _("Misc"), PREFS_PAGE_MISC);
 }
 
diff --git a/src/ui/dialog/inkscape-preferences.h b/src/ui/dialog/inkscape-preferences.h
index f81ff75d0..3a0a300a2 100644
--- a/src/ui/dialog/inkscape-preferences.h
+++ b/src/ui/dialog/inkscape-preferences.h
@@ -164,6 +164,7 @@ protected:
     PrefCheckButton _sel_layer_deselects;
 
     PrefSpinButton  _importexport_export, _misc_recent, _misc_simpl;
+    PrefSpinButton  _misc_latency_skew;
     PrefCheckButton _misc_comment, _misc_forkvectors, _misc_scripts;
     PrefCombo       _misc_small_toolbar;
     PrefCombo       _misc_small_secondary;
-- 
2.30.2