[PATCH libinput] touchpad: reduce middle button size on Dell touchpads to 10mm

[Peter Hutterer]

All Dell touchpas appear to have a visual marker on their touchpads. With a
visible marker our middle button can (and should) be much smaller since we
can rely on users to hit the button precisely.

https://bugs.freedesktop.org/show_bug.cgi?id=96710

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
Tested-by: Andy Lutomirski <luto at kernel.org>
---
 src/evdev-mt-touchpad-buttons.c    | 24 +++++++++++++++++++++---
 src/evdev.c                        |  1 +
 src/evdev.h                        |  1 +
 udev/90-libinput-model-quirks.hwdb |  7 +++++++
 4 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/src/evdev-mt-touchpad-buttons.c b/src/evdev-mt-touchpad-buttons.c
index a2f3121..cf49c83 100644
--- a/src/evdev-mt-touchpad-buttons.c
+++ b/src/evdev-mt-touchpad-buttons.c
@@ -544,13 +544,15 @@ tp_init_softbuttons(struct tp_dispatch *tp,
 	int width, height;
 	const struct input_absinfo *absinfo_x, *absinfo_y;
 	int xoffset, yoffset;
-	int yres;
+	int xres, yres;
+	int mb_le, mb_re; /* middle button left/right edge */
 
 	absinfo_x = device->abs.absinfo_x;
 	absinfo_y = device->abs.absinfo_y;
 
 	xoffset = absinfo_x->minimum,
 	yoffset = absinfo_y->minimum,
+	xres = absinfo_x->resolution;
 	yres = absinfo_y->resolution;
 	width = device->abs.dimensions.x;
 	height = device->abs.dimensions.y;
@@ -575,9 +577,25 @@ tp_init_softbuttons(struct tp_dispatch *tp,
 	 * touchpads don't have markings for the middle button at all so we
 	 * need to make it big enough to reliably hit it but not too big so
 	 * it takes away all the space.
+	 *
+	 * On touchpads with visible markings we reduce the size of the
+	 * middle button since users have a visual guide.
+	 *
+	 * All Dell touchpads appear to have a middle marker.
 	 */
-	tp->buttons.bottom_area.middlebutton_left_edge = width * 0.375 + xoffset;
-	tp->buttons.bottom_area.rightbutton_left_edge = width * 0.625 + xoffset;
+	if (tp->device->model_flags & EVDEV_MODEL_DELL_TOUCHPAD) {
+		const int MIDDLE_BUTTON_WIDTH = 10; /* mm */
+		int half_width = MIDDLE_BUTTON_WIDTH/2 * xres; /* units */
+
+		mb_le = xoffset + width/2 - half_width;
+		mb_re = xoffset + width/2 + half_width;
+	} else {
+		mb_le = xoffset + width * 0.375;
+		mb_re = xoffset + width * 0.625;
+	}
+
+	tp->buttons.bottom_area.middlebutton_left_edge = mb_le;
+	tp->buttons.bottom_area.rightbutton_left_edge = mb_re;
 }
 
 void
diff --git a/src/evdev.c b/src/evdev.c
index fdbaba1..6d231db 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -1804,6 +1804,7 @@ evdev_read_model_flags(struct evdev_device *device)
 		MODEL(CYBORG_RAT),
 		MODEL(CYAPA),
 		MODEL(LENOVO_T450_TOUCHPAD),
+		MODEL(DELL_TOUCHPAD),
 		MODEL(TRACKBALL),
 		MODEL(APPLE_MAGICMOUSE),
 		{ NULL, EVDEV_MODEL_DEFAULT },
diff --git a/src/evdev.h b/src/evdev.h
index 939a0b8..a3e76c5 100644
--- a/src/evdev.h
+++ b/src/evdev.h
@@ -115,6 +115,7 @@ enum evdev_device_model {
 	EVDEV_MODEL_CYBORG_RAT = (1 << 14),
 	EVDEV_MODEL_CYAPA = (1 << 15),
 	EVDEV_MODEL_LENOVO_T450_TOUCHPAD= (1 << 17),
+	EVDEV_MODEL_DELL_TOUCHPAD = (1 << 18),
 	EVDEV_MODEL_TRACKBALL = (1 << 19),
 	EVDEV_MODEL_APPLE_MAGICMOUSE = (1 << 20),
 };
diff --git a/udev/90-libinput-model-quirks.hwdb b/udev/90-libinput-model-quirks.hwdb
index 5e5ea9a..ebce8d2 100644
--- a/udev/90-libinput-model-quirks.hwdb
+++ b/udev/90-libinput-model-quirks.hwdb
@@ -48,6 +48,13 @@ libinput:mouse:input:b0003v06A3p0CD5*
  LIBINPUT_MODEL_CYBORG_RAT=1
 
 ##########################################
+# Dell
+##########################################
+libinput:name:SynPS/2 Synaptics TouchPad:dmi:*svnDellInc.:*
+libinput:name:* Touchpad:dmi:*svnDellInc.:*
+ LIBINPUT_MODEL_DELL_TOUCHPAD=1
+
+##########################################
 # Elantech
 ##########################################
 libinput:name:*ETPS/2 Elantech Touchpad*:dmi:*
-- 
2.7.4