[PATCH libinput 06/11] touchpad: scale thumb pressure threshold with the resolution

[Peter Hutterer]

On touchpads with a higher resolution we also see higher pressure values.
Scale accordingly, but use the T440s as reference and don't go below that
device's threshold. A false positive is worse than a false negative when it
comes to thumb detection.

https://bugs.freedesktop.org/show_bug.cgi?id=91362

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/evdev-mt-touchpad.c | 13 ++++++++++---
 test/touchpad.c         | 20 ++++++++++----------
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
index b4399d2..c7f55c3 100644
--- a/src/evdev-mt-touchpad.c
+++ b/src/evdev-mt-touchpad.c
@@ -1534,6 +1534,8 @@ tp_init_thumb(struct tp_dispatch *tp)
 	struct evdev_device *device = tp->device;
 	const struct input_absinfo *abs;
 	double w = 0.0, h = 0.0;
+	int xres, yres;
+	double threshold;
 
 	if (!tp->buttons.is_clickpad)
 		return 0;
@@ -1552,12 +1554,17 @@ tp_init_thumb(struct tp_dispatch *tp)
 	if (h < 50)
 		return 0;
 
-	/* The touchpads we looked at so far have a clear thumb threshold of
-	 * ~100, you don't reach that with a normal finger interaction.
+	/* Our reference touchpad is the T440s with 42x42 resolution.
+	 * Higher-res touchpads exhibit higher pressure for the same
+	 * interaction. On the T440s, the threshold value is 100, you don't
+	 * reach that with a normal finger interaction.
 	 * Note: "thumb" means massive touch that should not interact, not
 	 * "using the tip of my thumb for a pinch gestures".
 	 */
-	tp->thumb.threshold = 100;
+	xres = tp->device->abs.absinfo_x->resolution;
+	yres = tp->device->abs.absinfo_y->resolution;
+	threshold = 100.0 * hypot(xres, yres)/hypot(42, 42);
+	tp->thumb.threshold = max(100, threshold);
 	tp->thumb.detect_thumbs = true;
 
 	return 0;
diff --git a/test/touchpad.c b/test/touchpad.c
index 7b8324c..27485ae 100644
--- a/test/touchpad.c
+++ b/test/touchpad.c
@@ -4017,7 +4017,7 @@ START_TEST(touchpad_thumb_begin_no_motion)
 	struct litest_device *dev = litest_current_device();
 	struct libinput *li = dev->libinput;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4041,7 +4041,7 @@ START_TEST(touchpad_thumb_update_no_motion)
 	struct litest_device *dev = litest_current_device();
 	struct libinput *li = dev->libinput;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4071,7 +4071,7 @@ START_TEST(touchpad_thumb_clickfinger)
 	struct libinput_event *event;
 	struct libinput_event_pointer *ptrev;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4128,7 +4128,7 @@ START_TEST(touchpad_thumb_btnarea)
 	struct libinput_event *event;
 	struct libinput_event_pointer *ptrev;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4164,7 +4164,7 @@ START_TEST(touchpad_thumb_edgescroll)
 	struct litest_device *dev = litest_current_device();
 	struct libinput *li = dev->libinput;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4195,7 +4195,7 @@ START_TEST(touchpad_thumb_tap_begin)
 	struct litest_device *dev = litest_current_device();
 	struct libinput *li = dev->libinput;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4225,7 +4225,7 @@ START_TEST(touchpad_thumb_tap_touch)
 	struct litest_device *dev = litest_current_device();
 	struct libinput *li = dev->libinput;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4255,7 +4255,7 @@ START_TEST(touchpad_thumb_tap_hold)
 	struct litest_device *dev = litest_current_device();
 	struct libinput *li = dev->libinput;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4286,7 +4286,7 @@ START_TEST(touchpad_thumb_tap_hold_2ndfg)
 	struct litest_device *dev = litest_current_device();
 	struct libinput *li = dev->libinput;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
@@ -4333,7 +4333,7 @@ START_TEST(touchpad_thumb_tap_hold_2ndfg_tap)
 	struct libinput_event *event;
 	struct libinput_event_pointer *ptrev;
 	struct axis_replacement axes[] = {
-		{ ABS_MT_PRESSURE, 100 },
+		{ ABS_MT_PRESSURE, 190 },
 		{ -1, 0 }
 	};
 
-- 
2.4.3