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

[Hans de Goede]

Hi,

On 22-07-15 07:09, Peter Hutterer wrote:

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.hutte...@who-t.net>

Tricky, feels a bit like black magic, I cannot think of a better approach 
though,
so lets see how this works out:

Reviewed-by: Hans de Goede <hdego...@redhat.com>

Regards,

Hans

---
  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 }
        };

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