touchpad: add a config option to disable tap-and-drag

There are a number of use-cases where tapping may be desirable, but
tap-and-drag is not, e.g. where tapping is used to select multiple items in a
list. Having tap-and-drag on hinders this, and the nature of the interaction
means it cannot be detected based on timeouts, movement thresholds, etc.

Provide an option instead to turn tap-an-drag off. Tap-and-drag remains
enabled by default (though tapping is disabled by default).

For the touchpad tap state diagram, the new option disables the transition
from state TOUCH to state TAPPED and releases the button immediately instead.
This means that multitap-and-drag is disabled too since we now just loop
around in the single-tap state for multitap.

It also makes tapping more responsive - we don't have to wait for the timeout
before we know whether it's a tap event. The first touch time is noted, we now
send the button press with the time of the first touch and the release with
the time of the release. This ensures a realistic time diff between the two
events.

https://bugs.freedesktop.org/show_bug.cgi?id=93502

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

doc/tapping.dox

@@ -28,12 +28,16 @@ libinput_device_config_tap_set_enabled() for details.
 libinput also supports "tap-and-drag" where a tap immediately followed by a
 finger down and that finger being held down emulates a button press. Moving
 the finger around can thus drag the selected item on the screen.
+Tap-and-drag is optional and can be enabled or disabled with
+libinput_device_config_tap_set_drag_enabled(). Most devices have
+tap-and-drag enabled by default.
 
-Optional is a feature called "drag lock". With drag lock disabled, lifting
+Also optional is a feature called "drag lock". With drag lock disabled, lifting
 the finger will stop any drag process. When enabled, libinput will ignore a
 finger up event during a drag process, provided the finger is set down again
 within a implementation-specific timeout. Drag lock can be enabled and
 disabled with libinput_device_config_tap_set_drag_lock_enabled().
+Note that drag lock only applies if tap-and-drag is be enabled.
 
 @image html tap-n-drag.svg "Tap-and-drag process"
 

src/evdev-mt-touchpad-tap.c

@@ -153,6 +153,7 @@ tp_tap_idle_handle_event(struct tp_dispatch *tp,
 	switch (event) {
 	case TAP_EVENT_TOUCH:
 		tp->tap.state = TAP_STATE_TOUCH;
+		tp->tap.first_press_time = time;
 		tp_tap_set_timer(tp, time);
 		break;
 	case TAP_EVENT_RELEASE:
@@ -185,9 +186,14 @@ tp_tap_touch_handle_event(struct tp_dispatch *tp,
 		tp_tap_set_timer(tp, time);
 		break;
 	case TAP_EVENT_RELEASE:
-		tp->tap.state = TAP_STATE_TAPPED;
-		tp_tap_notify(tp, time, 1, LIBINPUT_BUTTON_STATE_PRESSED);
-		tp_tap_set_timer(tp, time);
+		tp_tap_notify(tp, tp->tap.first_press_time, 1, LIBINPUT_BUTTON_STATE_PRESSED);
+		if (tp->tap.drag_enabled) {
+			tp->tap.state = TAP_STATE_TAPPED;
+			tp_tap_set_timer(tp, time);
+		} else {
+			tp_tap_notify(tp, time, 1, LIBINPUT_BUTTON_STATE_RELEASED);
+			tp->tap.state = TAP_STATE_IDLE;
+		}
 		break;
 	case TAP_EVENT_TIMEOUT:
 	case TAP_EVENT_MOTION:
@@ -928,6 +934,44 @@ tp_tap_config_get_default(struct libinput_device *device)
 	return tp_tap_default(evdev);
 }
 
+static enum libinput_config_status
+tp_tap_config_set_drag_enabled(struct libinput_device *device,
+			       enum libinput_config_drag_state enabled)
+{
+	struct evdev_dispatch *dispatch = ((struct evdev_device *) device)->dispatch;
+	struct tp_dispatch *tp = NULL;
+
+	tp = container_of(dispatch, tp, base);
+	tp->tap.drag_enabled = enabled;
+
+	return LIBINPUT_CONFIG_STATUS_SUCCESS;
+}
+
+static enum libinput_config_drag_state
+tp_tap_config_get_drag_enabled(struct libinput_device *device)
+{
+	struct evdev_device *evdev = (struct evdev_device *)device;
+	struct tp_dispatch *tp = NULL;
+
+	tp = container_of(evdev->dispatch, tp, base);
+
+	return tp->tap.drag_enabled;
+}
+
+static inline enum libinput_config_drag_state
+tp_drag_default(struct evdev_device *device)
+{
+	return LIBINPUT_CONFIG_DRAG_ENABLED;
+}
+
+static enum libinput_config_drag_state
+tp_tap_config_get_default_drag_enabled(struct libinput_device *device)
+{
+	struct evdev_device *evdev = (struct evdev_device *)device;
+
+	return tp_drag_default(evdev);
+}
+
 static enum libinput_config_status
 tp_tap_config_set_draglock_enabled(struct libinput_device *device,
 				   enum libinput_config_drag_lock_state enabled)
@@ -973,6 +1017,9 @@ tp_init_tap(struct tp_dispatch *tp)
 	tp->tap.config.set_enabled = tp_tap_config_set_enabled;
 	tp->tap.config.get_enabled = tp_tap_config_is_enabled;
 	tp->tap.config.get_default = tp_tap_config_get_default;
+	tp->tap.config.set_drag_enabled = tp_tap_config_set_drag_enabled;
+	tp->tap.config.get_drag_enabled = tp_tap_config_get_drag_enabled;
+	tp->tap.config.get_default_drag_enabled = tp_tap_config_get_default_drag_enabled;
 	tp->tap.config.set_draglock_enabled = tp_tap_config_set_draglock_enabled;
 	tp->tap.config.get_draglock_enabled = tp_tap_config_get_draglock_enabled;
 	tp->tap.config.get_default_draglock_enabled = tp_tap_config_get_default_draglock_enabled;
@@ -980,6 +1027,7 @@ tp_init_tap(struct tp_dispatch *tp)
 
 	tp->tap.state = TAP_STATE_IDLE;
 	tp->tap.enabled = tp_tap_default(tp->device);
+	tp->tap.drag_enabled = tp_drag_default(tp->device);
 	tp->tap.drag_lock_enabled = tp_drag_lock_default(tp->device);
 
 	libinput_timer_init(&tp->tap.timer,

src/evdev-mt-touchpad.h

@@ -312,7 +312,9 @@ struct tp_dispatch {
 		struct libinput_timer timer;
 		enum tp_tap_state state;
 		uint32_t buttons_pressed;
+		uint64_t first_press_time;
 
+		bool drag_enabled;
 		bool drag_lock_enabled;
 	} tap;
 

src/libinput-private.h

@@ -120,6 +120,11 @@ struct libinput_device_config_tap {
 	enum libinput_config_tap_state (*get_enabled)(struct libinput_device *device);
 	enum libinput_config_tap_state (*get_default)(struct libinput_device *device);
 
+	enum libinput_config_status (*set_drag_enabled)(struct libinput_device *device,
+							enum libinput_config_drag_state);
+	enum libinput_config_drag_state (*get_drag_enabled)(struct libinput_device *device);
+	enum libinput_config_drag_state (*get_default_drag_enabled)(struct libinput_device *device);
+
 	enum libinput_config_status (*set_draglock_enabled)(struct libinput_device *device,
 							    enum libinput_config_drag_lock_state);
 	enum libinput_config_drag_lock_state (*get_draglock_enabled)(struct libinput_device *device);

src/libinput.c

@@ -2118,6 +2118,39 @@ libinput_device_config_tap_get_default_enabled(struct libinput_device *device)
 	return device->config.tap->get_default(device);
 }
 
+LIBINPUT_EXPORT enum libinput_config_status
+libinput_device_config_tap_set_drag_enabled(struct libinput_device *device,
+					    enum libinput_config_drag_state enable)
+{
+	if (enable != LIBINPUT_CONFIG_DRAG_ENABLED &&
+	    enable != LIBINPUT_CONFIG_DRAG_DISABLED)
+		return LIBINPUT_CONFIG_STATUS_INVALID;
+
+	if (libinput_device_config_tap_get_finger_count(device) == 0)
+		return enable ? LIBINPUT_CONFIG_STATUS_UNSUPPORTED :
+				LIBINPUT_CONFIG_STATUS_SUCCESS;
+
+	return device->config.tap->set_drag_enabled(device, enable);
+}
+
+LIBINPUT_EXPORT enum libinput_config_drag_state
+libinput_device_config_tap_get_drag_enabled(struct libinput_device *device)
+{
+	if (libinput_device_config_tap_get_finger_count(device) == 0)
+		return LIBINPUT_CONFIG_DRAG_DISABLED;
+
+	return device->config.tap->get_drag_enabled(device);
+}
+
+LIBINPUT_EXPORT enum libinput_config_drag_state
+libinput_device_config_tap_get_default_drag_enabled(struct libinput_device *device)
+{
+	if (libinput_device_config_tap_get_finger_count(device) == 0)
+		return LIBINPUT_CONFIG_DRAG_DISABLED;
+
+	return device->config.tap->get_default_drag_enabled(device);
+}
+
 LIBINPUT_EXPORT enum libinput_config_status
 libinput_device_config_tap_set_drag_lock_enabled(struct libinput_device *device,
 						 enum libinput_config_drag_lock_state enable)

src/libinput.h

@@ -2180,6 +2180,79 @@ libinput_device_config_tap_get_enabled(struct libinput_device *device);
 enum libinput_config_tap_state
 libinput_device_config_tap_get_default_enabled(struct libinput_device *device);
 
+/**
+ * @ingroup config
+ *
+ * A config status to distinguish or set dragging on a device. Currently
+ * implemented for tap-and-drag only, see
+ * libinput_device_config_tap_set_drag_enabled()
+ */
+enum libinput_config_drag_state {
+	/**
+	 * Drag is to be disabled, or is
+	 * currently disabled.
+	 */
+	LIBINPUT_CONFIG_DRAG_DISABLED,
+	/**
+	 * Drag is to be enabled, or is
+	 * currently enabled
+	 */
+	LIBINPUT_CONFIG_DRAG_ENABLED,
+};
+
+/**
+ * @ingroup config
+ *
+ * Enable or disable tap-and-drag on this device. When enabled, a
+ * single-finger tap immediately followed by a finger down results in a
+ * button down event, subsequent finger motion thus triggers a drag. The
+ * button is released on finger up. See @ref tapndrag for more details.
+ *
+ * @param device The device to configure
+ * @param enable @ref LIBINPUT_CONFIG_DRAG_ENABLED to enable, @ref
+ * LIBINPUT_CONFIG_DRAG_DISABLED to disable tap-and-drag
+ *
+ * @see libinput_device_config_tap_drag_get_enabled
+ * @see libinput_device_config_tap_drag_get_default_enabled
+ */
+enum libinput_config_status
+libinput_device_config_tap_set_drag_enabled(struct libinput_device *device,
+					    enum libinput_config_drag_state enable);
+
+/**
+ * @ingroup config
+ *
+ * Return whether tap-and-drag is enabled or disabled on this device.
+ *
+ * @param device The device to check
+ * @retval LIBINPUT_CONFIG_DRAG_ENABLED if tap-and-drag is enabled
+ * @retval LIBINPUT_CONFIG_DRAG_DISABLED if tap-and-drag is
+ * disabled
+ *
+ * @see libinput_device_config_tap_drag_set_enabled
+ * @see libinput_device_config_tap_drag_get_default_enabled
+ */
+enum libinput_config_drag_state
+libinput_device_config_tap_get_drag_enabled(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Return whether tap-and-drag is enabled or disabled by default on this
+ * device.
+ *
+ * @param device The device to check
+ * @retval LIBINPUT_CONFIG_DRAG_ENABLED if tap-and-drag is enabled by
+ * default
+ * @retval LIBINPUT_CONFIG_DRAG_DISABLED if tap-and-drag is
+ * disabled by default
+ *
+ * @see libinput_device_config_tap_drag_set_enabled
+ * @see libinput_device_config_tap_drag_get_enabled
+ */
+enum libinput_config_drag_state
+libinput_device_config_tap_get_default_drag_enabled(struct libinput_device *device);
+
 /**
  * @ingroup config
  */

src/libinput.sym

@@ -179,3 +179,9 @@ LIBINPUT_1.1 {
 	libinput_device_config_accel_get_default_profile;
 	libinput_device_config_accel_set_profile;
 } LIBINPUT_0.21.0;
+
+LIBINPUT_1.2 {
+	libinput_device_config_tap_get_drag_enabled;
+	libinput_device_config_tap_get_default_drag_enabled;
+	libinput_device_config_tap_set_drag_enabled;
+} LIBINPUT_1.1;

test/litest.h

@@ -493,6 +493,30 @@ litest_disable_tap(struct libinput_device *device)
 	litest_assert_int_eq(status, expected);
 }
 
+static inline void
+litest_enable_tap_drag(struct libinput_device *device)
+{
+	enum libinput_config_status status, expected;
+
+	expected = LIBINPUT_CONFIG_STATUS_SUCCESS;
+	status = libinput_device_config_tap_set_drag_enabled(device,
+							     LIBINPUT_CONFIG_DRAG_ENABLED);
+
+	litest_assert_int_eq(status, expected);
+}
+
+static inline void
+litest_disable_tap_drag(struct libinput_device *device)
+{
+	enum libinput_config_status status, expected;
+
+	expected = LIBINPUT_CONFIG_STATUS_SUCCESS;
+	status = libinput_device_config_tap_set_drag_enabled(device,
+							     LIBINPUT_CONFIG_DRAG_DISABLED);
+
+	litest_assert_int_eq(status, expected);
+}
+
 static inline bool
 litest_has_2fg_scroll(struct litest_device *dev)
 {

test/touchpad-tap.c

@@ -1723,6 +1723,187 @@ START_TEST(touchpad_tap_invalid)
 }
 END_TEST
 
+START_TEST(touchpad_drag_default_disabled)
+{
+	struct litest_device *dev = litest_current_device();
+
+	/* this test is only run on specific devices */
+
+	ck_assert_int_eq(libinput_device_config_tap_get_default_drag_enabled(dev->libinput_device),
+			 LIBINPUT_CONFIG_DRAG_DISABLED);
+}
+END_TEST
+
+START_TEST(touchpad_drag_default_enabled)
+{
+	struct litest_device *dev = litest_current_device();
+
+	/* this test is only run on specific devices */
+
+	ck_assert_int_eq(libinput_device_config_tap_get_default_drag_enabled(dev->libinput_device),
+			 LIBINPUT_CONFIG_DRAG_ENABLED);
+}
+END_TEST
+
+START_TEST(touchpad_drag_config_invalid)
+{
+	struct litest_device *dev = litest_current_device();
+
+	ck_assert_int_eq(libinput_device_config_tap_set_drag_enabled(dev->libinput_device, 2),
+			 LIBINPUT_CONFIG_STATUS_INVALID);
+	ck_assert_int_eq(libinput_device_config_tap_set_drag_enabled(dev->libinput_device, -1),
+			 LIBINPUT_CONFIG_STATUS_INVALID);
+}
+END_TEST
+
+START_TEST(touchpad_drag_config_enabledisable)
+{
+	struct litest_device *dev = litest_current_device();
+	enum libinput_config_drag_state state;
+
+	litest_enable_tap(dev->libinput_device);
+
+	litest_disable_tap_drag(dev->libinput_device);
+	state = libinput_device_config_tap_get_drag_enabled(dev->libinput_device);
+	ck_assert_int_eq(state, LIBINPUT_CONFIG_DRAG_DISABLED);
+
+	litest_enable_tap_drag(dev->libinput_device);
+	state = libinput_device_config_tap_get_drag_enabled(dev->libinput_device);
+	ck_assert_int_eq(state, LIBINPUT_CONFIG_DRAG_ENABLED);
+
+	/* same thing with tapping disabled */
+	litest_enable_tap(dev->libinput_device);
+
+	litest_disable_tap_drag(dev->libinput_device);
+	state = libinput_device_config_tap_get_drag_enabled(dev->libinput_device);
+	ck_assert_int_eq(state, LIBINPUT_CONFIG_DRAG_DISABLED);
+
+	litest_enable_tap_drag(dev->libinput_device);
+	state = libinput_device_config_tap_get_drag_enabled(dev->libinput_device);
+	ck_assert_int_eq(state, LIBINPUT_CONFIG_DRAG_ENABLED);
+}
+END_TEST
+
+START_TEST(touchpad_drag_disabled)
+{
+	struct litest_device *dev = litest_current_device();
+	struct libinput *li = dev->libinput;
+
+	litest_enable_tap(dev->libinput_device);
+	litest_disable_tap_drag(dev->libinput_device);
+
+	litest_drain_events(li);
+
+	litest_touch_down(dev, 0, 50, 50);
+	litest_touch_up(dev, 0);
+	libinput_dispatch(li);
+	litest_touch_down(dev, 0, 50, 50);
+	litest_touch_move_to(dev, 0, 50, 50, 90, 90, 10, 0);
+	litest_touch_up(dev, 0);
+	libinput_dispatch(li);
+
+	litest_assert_button_event(li,
+				   BTN_LEFT,
+				   LIBINPUT_BUTTON_STATE_PRESSED);
+	litest_assert_button_event(li,
+				   BTN_LEFT,
+				   LIBINPUT_BUTTON_STATE_RELEASED);
+	litest_assert_only_typed_events(li,
+					LIBINPUT_EVENT_POINTER_MOTION);
+
+}
+END_TEST
+
+START_TEST(touchpad_drag_disabled_immediate)
+{
+	struct litest_device *dev = litest_current_device();
+	struct libinput *li = dev->libinput;
+	struct libinput_event *ev;
+	struct libinput_event_pointer *ptrev;
+	uint64_t press_time, release_time;
+
+	litest_enable_tap(dev->libinput_device);
+	litest_disable_tap_drag(dev->libinput_device);
+
+	litest_drain_events(li);
+
+	litest_touch_down(dev, 0, 50, 50);
+	msleep(10); /* to force a time difference */
+	libinput_dispatch(li);
+	litest_touch_up(dev, 0);
+	libinput_dispatch(li);
+
+	ev = libinput_get_event(li);
+	ptrev = litest_is_button_event(ev,
+				       BTN_LEFT,
+				       LIBINPUT_BUTTON_STATE_PRESSED);
+	press_time = libinput_event_pointer_get_time(ptrev);
+	libinput_event_destroy(ev);
+
+	ev = libinput_get_event(li);
+	ptrev = litest_is_button_event(ev,
+				       BTN_LEFT,
+				       LIBINPUT_BUTTON_STATE_RELEASED);
+	release_time = libinput_event_pointer_get_time(ptrev);
+	libinput_event_destroy(ev);
+
+	ck_assert_int_gt(release_time, press_time);
+}
+END_TEST
+
+START_TEST(touchpad_drag_disabled_multitap_no_drag)
+{
+	struct litest_device *dev = litest_current_device();
+	struct libinput *li = dev->libinput;
+	struct libinput_event *event;
+	struct libinput_event_pointer *ptrev;
+	uint32_t oldtime = 0,
+		 curtime;
+	int range = _i, /* looped test */
+	    ntaps;
+
+	litest_enable_tap(dev->libinput_device);
+	litest_disable_tap_drag(dev->libinput_device);
+
+	litest_drain_events(li);
+
+	for (ntaps = 0; ntaps <= range; ntaps++) {
+		litest_touch_down(dev, 0, 50, 50);
+		litest_touch_up(dev, 0);
+		libinput_dispatch(li);
+		msleep(10);
+	}
+
+	libinput_dispatch(li);
+	litest_touch_down(dev, 0, 50, 50);
+	litest_touch_move_to(dev, 0, 50, 50, 70, 50, 10, 4);
+	libinput_dispatch(li);
+
+	for (ntaps = 0; ntaps <= range; ntaps++) {
+		event = libinput_get_event(li);
+		ptrev = litest_is_button_event(event,
+					       BTN_LEFT,
+					       LIBINPUT_BUTTON_STATE_PRESSED);
+		curtime = libinput_event_pointer_get_time(ptrev);
+		libinput_event_destroy(event);
+		ck_assert_int_gt(curtime, oldtime);
+
+		event = libinput_get_event(li);
+		ptrev = litest_is_button_event(event,
+					       BTN_LEFT,
+					       LIBINPUT_BUTTON_STATE_RELEASED);
+		curtime = libinput_event_pointer_get_time(ptrev);
+		libinput_event_destroy(event);
+		ck_assert_int_ge(curtime, oldtime);
+		oldtime = curtime;
+	}
+
+	litest_assert_only_typed_events(li,
+					LIBINPUT_EVENT_POINTER_MOTION);
+	litest_assert_empty_queue(li);
+}
+END_TEST
+
 START_TEST(touchpad_drag_lock_default_disabled)
 {
 	struct litest_device *dev = litest_current_device();
@@ -1838,4 +2019,11 @@ litest_setup_tests(void)
 	litest_add("tap:draglock", touchpad_drag_lock_default_disabled, LITEST_TOUCHPAD, LITEST_ANY);
 	litest_add("tap:draglock", touchpad_drag_lock_default_unavailable, LITEST_ANY, LITEST_TOUCHPAD);
 
+	litest_add("tap:drag", touchpad_drag_default_disabled, LITEST_ANY, LITEST_TOUCHPAD);
+	litest_add("tap:drag", touchpad_drag_default_enabled, LITEST_TOUCHPAD, LITEST_BUTTON);
+	litest_add("tap:drag", touchpad_drag_config_invalid, LITEST_TOUCHPAD, LITEST_ANY);
+	litest_add("tap:drag", touchpad_drag_config_enabledisable, LITEST_TOUCHPAD, LITEST_ANY);
+	litest_add("tap:drag", touchpad_drag_disabled, LITEST_TOUCHPAD, LITEST_ANY);
+	litest_add("tap:drag", touchpad_drag_disabled_immediate, LITEST_TOUCHPAD, LITEST_ANY);
+	litest_add_ranged("tap:drag", touchpad_drag_disabled_multitap_no_drag, LITEST_TOUCHPAD, LITEST_ANY, &multitap_range);
 }

tools/libinput-list-devices.c

@@ -47,6 +47,18 @@ tap_default(struct libinput_device *device)
 		return "disabled";
 }
 
+static const char *
+drag_default(struct libinput_device *device)
+{
+	if (!libinput_device_config_tap_get_finger_count(device))
+		return "n/a";
+
+	if (libinput_device_config_tap_get_default_drag_enabled(device))
+		return "enabled";
+	else
+		return "disabled";
+}
+
 static const char *
 draglock_default(struct libinput_device *device)
 {
@@ -260,6 +272,7 @@ print_device_notify(struct libinput_event *ev)
 	printf("\n");
 
 	printf("Tap-to-click:     %s\n", tap_default(dev));
+	printf("Tap-and-drag:     %s\n",  drag_default(dev));
 	printf("Tap drag lock:    %s\n", draglock_default(dev));
 	printf("Left-handed:      %s\n", left_handed_default(dev));
 	printf("Nat.scrolling:    %s\n", nat_scroll_default(dev));

tools/shared.c

@@ -45,6 +45,8 @@ enum options {
 	OPT_VERBOSE,
 	OPT_TAP_ENABLE,
 	OPT_TAP_DISABLE,
+	OPT_DRAG_ENABLE,
+	OPT_DRAG_DISABLE,
 	OPT_DRAG_LOCK_ENABLE,
 	OPT_DRAG_LOCK_DISABLE,
 	OPT_NATURAL_SCROLL_ENABLE,
@@ -82,6 +84,8 @@ tools_usage()
 	       "Features:\n"
 	       "--enable-tap\n"
 	       "--disable-tap.... enable/disable tapping\n"
+	       "--enable-drag\n"
+	       "--disable-drag.... enable/disable tap-n-drag\n"
 	       "--enable-drag-lock\n"
 	       "--disable-drag-lock.... enable/disable tapping drag lock\n"
 	       "--enable-natural-scrolling\n"
@@ -117,6 +121,7 @@ tools_init_context(struct tools_context *context)
 
 	memset(options, 0, sizeof(*options));
 	options->tapping = -1;
+	options->drag = -1;
 	options->drag_lock = -1;
 	options->natural_scroll = -1;
 	options->left_handed = -1;
@@ -147,6 +152,8 @@ tools_parse_args(int argc, char **argv, struct tools_context *context)
 			{ "verbose", 0, 0, OPT_VERBOSE },
 			{ "enable-tap", 0, 0, OPT_TAP_ENABLE },
 			{ "disable-tap", 0, 0, OPT_TAP_DISABLE },
+			{ "enable-drag", 0, 0, OPT_DRAG_ENABLE },
+			{ "disable-drag", 0, 0, OPT_DRAG_DISABLE },
 			{ "enable-drag-lock", 0, 0, OPT_DRAG_LOCK_ENABLE },
 			{ "disable-drag-lock", 0, 0, OPT_DRAG_LOCK_DISABLE },
 			{ "enable-natural-scrolling", 0, 0, OPT_NATURAL_SCROLL_ENABLE },
@@ -199,6 +206,12 @@ tools_parse_args(int argc, char **argv, struct tools_context *context)
 		case OPT_TAP_DISABLE:
 			options->tapping = 0;
 			break;
+		case OPT_DRAG_ENABLE:
+			options->drag = 1;
+			break;
+		case OPT_DRAG_DISABLE:
+			options->drag = 0;
+			break;
 		case OPT_DRAG_LOCK_ENABLE:
 			options->drag_lock = 1;
 			break;
@@ -438,6 +451,9 @@ tools_device_apply_config(struct libinput_device *device,
 {
 	if (options->tapping != -1)
 		libinput_device_config_tap_set_enabled(device, options->tapping);
+	if (options->drag != -1)
+		libinput_device_config_tap_set_drag_enabled(device,
+							    options->drag);
 	if (options->drag_lock != -1)
 		libinput_device_config_tap_set_drag_lock_enabled(device,
 								 options->drag_lock);

tools/shared.h

@@ -39,6 +39,7 @@ struct tools_options {
 
 	int verbose;
 	int tapping;
+	int drag;
 	int drag_lock;
 	int natural_scroll;
 	int left_handed;