Attachment 128092 Details for Bug 90735 – 0001-touchpad-only-use-the-last-two-coordinates-for-delta.patch

[patch] 0001-touchpad-only-use-the-last-two-coordinates-for-delta.patch

0001-touchpad-only-use-the-last-two-coordinates-for-delta.patch (text/plain), 2.12 KB, created by Peter Hutterer on 2016-11-21 05:35:45 UTC

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Creator: Peter Hutterer

Created: 2016-11-21 05:35:45 UTC

Size: 2.12 KB

patch

obsolete

>From e288c3045d0c582ee19e85cbe11529dc374d4bbf Mon Sep 17 00:00:00 2001
>From: Peter Hutterer <peter.hutterer@who-t.net>
>Date: Mon, 21 Nov 2016 08:39:47 +1000
>Subject: [PATCH libinput] touchpad: only use the last two coordinates for
> delta calculation
>
>Taking the last 4 points means factoring in a coordinate that may be more than
>40ms in the past - or even more when the finger moves slowly and we don't get
>events for a while. This makes the pointer more sluggish and slower to catch up
>with what the finger is actually doing.
>
>We already have the motion hysteresis as a separate item to prevent jumps (and
>thus adds some delay to the movement), the calculation over time doesn't
>provide enough benefit to justify the sluggish pointer.
>
>Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
>---
> src/evdev-mt-touchpad.c | 20 +++++---------------
> 1 file changed, 5 insertions(+), 15 deletions(-)
>
>diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
>index d72cb19..7b8514c 100644
>--- a/src/evdev-mt-touchpad.c
>+++ b/src/evdev-mt-touchpad.c
>@@ -262,29 +262,19 @@ tp_end_sequence(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
> 	tp_end_touch(tp, t, time);
> }
> 
>-static double
>-tp_estimate_delta(int x0, int x1, int x2, int x3)
>-{
>-	return (x0 + x1 - x2 - x3) / 4.0;
>-}
>-
> struct normalized_coords
> tp_get_delta(struct tp_touch *t)
> {
> 	struct device_float_coords delta;
> 	const struct normalized_coords zero = { 0.0, 0.0 };
> 
>-	if (t->history.count < TOUCHPAD_MIN_SAMPLES)
>+	if (t->history.count <= 1)
> 		return zero;
> 
>-	delta.x = tp_estimate_delta(tp_motion_history_offset(t, 0)->x,
>-				    tp_motion_history_offset(t, 1)->x,
>-				    tp_motion_history_offset(t, 2)->x,
>-				    tp_motion_history_offset(t, 3)->x);
>-	delta.y = tp_estimate_delta(tp_motion_history_offset(t, 0)->y,
>-				    tp_motion_history_offset(t, 1)->y,
>-				    tp_motion_history_offset(t, 2)->y,
>-				    tp_motion_history_offset(t, 3)->y);
>+	delta.x = tp_motion_history_offset(t, 0)->x -
>+		  tp_motion_history_offset(t, 1)->x;
>+	delta.y = tp_motion_history_offset(t, 0)->y -
>+		  tp_motion_history_offset(t, 1)->y;
> 
> 	return tp_normalize_delta(t->tp, delta);
> }
>-- 
>2.9.3
>

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