Cap the minimum acceleration slowdown at 0.3 (#1227796)

0001-filter-require-minimum-acceleration-factor-of-0.3.patch

@@ -0,0 +1,52 @@
+From f6313a9d010f03a66fd1f68e0bbd5e073101f342 Mon Sep 17 00:00:00 2001
+From: Peter Hutterer <peter.hutterer@who-t.net>
+Date: Thu, 4 Jun 2015 11:40:15 +1000
+Subject: [PATCH libinput] filter: require minimum acceleration factor of 0.3
+
+For really slow motions, the previous acceleration factor would go down to
+effectively zero. So the slower the mouse motion was, the more it would be
+slowed down which made the mouse at low speeds almost unusable.
+
+Cap the minimum acceleration at 0.3 which provides a predictable slow motion
+for the cursor when high precision is required.
+
+New/old acceleration functions comparison:
+
+  ^
+  |               /
+  |              /
+ty|    _________/
+  |   / /
+  |  / /
+  | / /
+  |/ /    <----- new minimum accel factor
+  | /
+  |/___________________>
+      tx
+
+i.e. the general shape is maintained, but it doesn't go to zero anymore. The
+functions aren't parallel, the new shape is slightly flatter than the previous
+one and they meet at the point where the functions flatten for the threshold
+(tx/ty). ascii art has its limits...
+
+Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
+---
+ src/filter.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/filter.c b/src/filter.c
+index c54d866..ed5a184 100644
+--- a/src/filter.c
++++ b/src/filter.c
+@@ -354,7 +354,7 @@ pointer_accel_profile_linear(struct motion_filter *filter,
+ 	const double threshold = accel_filter->threshold; /* units/ms */
+ 	const double incline = accel_filter->incline;
+ 
+-	s1 = min(1, speed_in * 5);
++	s1 = min(1, 0.3 + speed_in * 4);
+ 	s2 = 1 + (speed_in - threshold) * incline;
+ 
+ 	return min(max_accel, s2 > 1 ? s2 : s1);
+-- 
+2.4.1
+

libinput.spec

@@ -5,7 +5,7 @@
 
 Name:           libinput
 Version:        0.17.0
-Release:        1%{?gitdate:.%{gitdate}git%{gitversion}}%{?dist}
+Release:        2%{?gitdate:.%{gitdate}git%{gitversion}}%{?dist}
 Summary:        Input device library
 
 License:        MIT
@@ -18,6 +18,8 @@ Source2:        commitid
 Source0:        http://www.freedesktop.org/software/libinput/libinput-%{version}.tar.xz
 %endif
 
+Patch01:        0001-filter-require-minimum-acceleration-factor-of-0.3.patch
+
 BuildRequires:  git
 BuildRequires:  autoconf automake libtool pkgconfig
 BuildRequires:  libevdev-devel
@@ -93,6 +95,9 @@ find $RPM_BUILD_ROOT -name '*.la' -delete
 
 
 %changelog
+* Tue Jun 09 2015 Peter Hutterer <peter.hutterer@redhat.com> 0.17.0-2
+- Cap the minimum acceleration slowdown at 0.3 (#1227796)
+
 * Thu Jun 04 2015 Peter Hutterer <peter.hutterer@redhat.com> 0.17.0-1
 - libinput 0.17