Three finger dragging (TFD) state machine

Including explicit states for 4+ finger gesture disambiguation,
drag-lock timeout, and click/tap to drop.

Signed-off-by: Temp Name <test@example.com>

meson.build

@@ -350,6 +350,7 @@ src_libinput = src_libfilter + [
 	'src/evdev-middle-button.c',
 	'src/evdev-mt-touchpad.c',
 	'src/evdev-mt-touchpad-tap.c',
+	'src/evdev-mt-touchpad-tfd.c',
 	'src/evdev-mt-touchpad-thumb.c',
 	'src/evdev-mt-touchpad-buttons.c',
 	'src/evdev-mt-touchpad-edge-scroll.c',

src/evdev-mt-touchpad-gestures.c

@@ -1303,7 +1303,7 @@ tp_gesture_post_events(struct tp_dispatch *tp, uint64_t time,
 	 * physical button is down, don't allow gestures unless the button
 	 * is held down by a *thumb*, specifically.
 	 */
-	if (tp_tap_dragging(tp) ||
+	if (tp_tap_dragging(tp) || tp_tfd_dragging(tp) ||
 	    (tp->buttons.is_clickpad && tp->buttons.state &&
 	     tp->thumb.state == THUMB_STATE_FINGER)) {
 		if (tp->gesture.state != GESTURE_STATE_POINTER_MOTION) {
@@ -1430,7 +1430,8 @@ tp_gesture_handle_state(struct tp_dispatch *tp, uint64_t time)
 			active_touches++;
 	}
 
-	if (active_touches != tp->gesture.finger_count) {
+	if (active_touches != tp->gesture.finger_count || 
+	    (active_touches == 3 && true)) { // tp->tfd.three_finger_dragging_enabled)) {
 		/* If all fingers are lifted immediately end the gesture */
 		if (active_touches == 0) {
 			tp_gesture_stop(tp, time);

src/evdev-mt-touchpad-tap.c

@@ -143,10 +143,14 @@ tp_tap_notify(struct tp_dispatch *tp,
 	else
 		tp->tap.buttons_pressed &= ~bit(nfingers);
 
+
 	evdev_pointer_notify_button(tp->device,
 				    time,
 				    button,
 				    state);
+					
+	if (state != LIBINPUT_BUTTON_STATE_PRESSED)
+		tp_tfd_handle_tap(tp, time);
 }
 
 static void

src/evdev-mt-touchpad.c

@@ -846,6 +846,10 @@ tp_touch_active_for_gesture(const struct tp_dispatch *tp, const struct tp_touch
 	return (t->state == TOUCH_BEGIN || t->state == TOUCH_UPDATE) &&
 		t->palm.state == PALM_NONE &&
 		!t->pinned.is_pinned &&
+
+		/* let's see if this works */
+		!tp->tfd.cursor_pinned &&
+
 		!tp_thumb_ignored_for_gesture(tp, t) &&
 		tp_button_touch_active(tp, t) &&
 		tp_edge_scroll_touch_active(tp, t);
@@ -1863,6 +1867,8 @@ tp_post_events(struct tp_dispatch *tp, uint64_t time)
 	ignore_motion |= tp_tap_handle_state(tp, time);
 	ignore_motion |= tp_post_button_events(tp, time);
 
+	tp_tfd_handle_state(tp, time);
+
 	if (tp->palm.trackpoint_active || tp->dwt.keyboard_active) {
 		tp_edge_scroll_stop_events(tp, time);
 		tp_gesture_cancel(tp, time);
@@ -3777,6 +3783,8 @@ tp_init(struct tp_dispatch *tp,
 	if (!tp_init_accel(tp, LIBINPUT_CONFIG_ACCEL_PROFILE_ADAPTIVE))
 		return false;
 
+	tp_init_tfd(tp);
+	
 	tp_init_tap(tp);
 	tp_init_buttons(tp, device);
 	tp_init_dwt(tp, device);

src/evdev-mt-touchpad.h

@@ -134,6 +134,20 @@ enum tp_tap_state {
 	TAP_STATE_DEAD, /**< finger count exceeded */
 };
 
+
+enum tp_tfd_state {
+	/* waiting for 3 fingers */
+	TFD_STATE_IDLE,
+	/* 3 fingers down, possible 4+ f gesture */
+	TFD_STATE_POSSIBLE_DRAG,
+	/* 3 fingers down and button press has been output */
+	TFD_STATE_DRAG,
+	/* drag-lock; waiting for drag continuation */
+	TFD_STATE_AWAIT_RESUME,
+	/* disambiguate between drag continuation and a possible 4+ gesture */
+	TFD_STATE_POSSIBLE_RESUME,
+};
+
 enum tp_tap_touch_state {
 	TAP_TOUCH_STATE_IDLE = 16,	/**< not in touch */
 	TAP_TOUCH_STATE_TOUCH,		/**< touching, may tap */
@@ -250,6 +264,13 @@ struct tp_touch {
 		bool is_palm;
 	} tap;
 
+	struct {
+		// enum tp_tap_touch_state state;
+		struct device_coords previous;
+		// bool is_thumb;
+		// bool is_palm;
+	} tfd;
+
 	struct {
 		enum tp_edge_scroll_touch_state edge_state;
 		uint32_t edge;
@@ -440,6 +461,31 @@ struct tp_dispatch {
 		unsigned int nfingers_down;	/* number of fingers down for tapping (excl. thumb/palm) */
 	} tap;
 
+		struct {
+		//struct libinput_device_config_tap config;
+		bool enabled;
+		bool suspended;
+		struct libinput_timer timer;
+		struct libinput_timer resume_timer;
+		enum tp_tfd_state state;
+		uint32_t buttons_pressed;
+		uint64_t saved_press_time,
+			 saved_release_time;
+
+		// enum libinput_config_tap_button_map map;
+		//enum libinput_config_tap_button_map want_map;
+
+		/* true if cursor movement should not be output to clients */
+		bool cursor_pinned;
+		struct device_coords pinned_point;
+
+		//bool drag_enabled;
+		//bool drag_lock_enabled;
+		bool three_finger_dragging_enabled;
+
+		unsigned int finger_count;	/* number of fingers down for 3 finger dragging */
+	} tfd;
+
 	struct {
 		struct libinput_device_config_dwtp config;
 		bool dwtp_enabled;
@@ -625,6 +671,12 @@ tp_touch_active_for_gesture(const struct tp_dispatch *tp,
 int
 tp_tap_handle_state(struct tp_dispatch *tp, uint64_t time);
 
+void
+tp_tfd_handle_state(struct tp_dispatch *tp, uint64_t time);
+
+void
+tp_tfd_handle_tap(struct tp_dispatch *tp, uint64_t time);
+
 void
 tp_tap_post_process_state(struct tp_dispatch *tp);