touchpad: set the finger pin distance to 5mm where possible

On touchpads with resolutions, use a 5mm motion threshold before we unpin the
finger (allow motion events while a clickpad button is down). This should
remove any erroneous finger movements while clicking, at the cost of having to
move the finger a bit more for a single-finger click-and-drag (use two fingers
already!)

And drop the finger drifting, it was per-event based rather than time-based.
So unless the motion threshold was hit in a single event it was possible to
move the finger around the whole touchpad without ever unpinning it.

Drop the finger drifting altogether, if the touchpad drifts by more than 5mm
we have other issues.

https://bugzilla.redhat.com/show_bug.cgi?id=1230462

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/src/evdev-mt-touchpad-buttons.c b/src/evdev-mt-touchpad-buttons.c
index 5786ea8b..eb0ddcb0 100644
--- a/src/evdev-mt-touchpad-buttons.c
+++ b/src/evdev-mt-touchpad-buttons.c
@@ -31,7 +31,6 @@
 
 #include "evdev-mt-touchpad.h"
 
-#define DEFAULT_BUTTON_MOTION_THRESHOLD 0.02 /* 2% of size */
 #define DEFAULT_BUTTON_ENTER_TIMEOUT 100 /* ms */
 #define DEFAULT_BUTTON_LEAVE_TIMEOUT 300 /* ms */
 
@@ -709,11 +708,19 @@ tp_init_buttons(struct tp_dispatch *tp,
 	absinfo_x = device->abs.absinfo_x;
 	absinfo_y = device->abs.absinfo_y;
 
-	width = abs(absinfo_x->maximum - absinfo_x->minimum);
-	height = abs(absinfo_y->maximum - absinfo_y->minimum);
-	diagonal = sqrt(width*width + height*height);
-
-	tp->buttons.motion_dist = diagonal * DEFAULT_BUTTON_MOTION_THRESHOLD;
+	/* pinned-finger motion threshold, see tp_unpin_finger.
+	   The MAGIC for resolution-less touchpads ends up as 2% of the diagonal */
+	if (device->abs.fake_resolution) {
+		const int BUTTON_MOTION_MAGIC = 0.007;
+		width = abs(absinfo_x->maximum - absinfo_x->minimum);
+		height = abs(absinfo_y->maximum - absinfo_y->minimum);
+		diagonal = sqrt(width*width + height*height);
+		tp->buttons.motion_dist.x_scale_coeff = diagonal * BUTTON_MOTION_MAGIC;
+		tp->buttons.motion_dist.y_scale_coeff = diagonal * BUTTON_MOTION_MAGIC;
+	} else {
+		tp->buttons.motion_dist.x_scale_coeff = 1.0/absinfo_x->resolution;
+		tp->buttons.motion_dist.y_scale_coeff = 1.0/absinfo_y->resolution;
+	}
 
 	tp->buttons.config_method.get_methods = tp_button_config_click_get_methods;
 	tp->buttons.config_method.set_method = tp_button_config_click_set_method;