From e5932867f1c939cf3deb3dd575fb61572b5d872e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= <jose.exposito89@gmail.com>
Date: Mon, 20 Sep 2021 19:47:07 +0200
Subject: [PATCH] backend/wayland: handle high-res scroll events

Receive high-resolution scroll events from the parent compositor using
a Wayland listiner and emit the appropiate wlr_pointer signal.
---
 backend/wayland/backend.c |  2 +-
 backend/wayland/seat.c    | 43 +++++++++++++++++++++++++++++++--------
 include/backend/wayland.h |  1 +
 3 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/backend/wayland/backend.c b/backend/wayland/backend.c
index c11d25ca9..da3ec2ea5 100644
--- a/backend/wayland/backend.c
+++ b/backend/wayland/backend.c
@@ -211,7 +211,7 @@ static void registry_global(void *data, struct wl_registry *registry,
 			&wl_compositor_interface, 4);
 	} else if (strcmp(iface, wl_seat_interface.name) == 0) {
 		struct wl_seat *wl_seat = wl_registry_bind(registry, name,
-			&wl_seat_interface, 5);
+			&wl_seat_interface, version < 8 ? version : 8);
 		if (!create_wl_seat(wl_seat, wl)) {
 			wl_seat_destroy(wl_seat);
 		}
diff --git a/backend/wayland/seat.c b/backend/wayland/seat.c
index 05524a7ed..bcbaecd99 100644
--- a/backend/wayland/seat.c
+++ b/backend/wayland/seat.c
@@ -129,15 +129,28 @@ static void pointer_handle_axis(void *data, struct wl_pointer *wl_pointer,
 		return;
 	}
 
-	struct wlr_event_pointer_axis event = {
-		.device = &pointer->input_device->wlr_input_device,
-		.delta = wl_fixed_to_double(value),
-		.delta_discrete = pointer->axis_discrete,
-		.orientation = axis,
-		.time_msec = time,
-		.source = pointer->axis_source,
-	};
-	wlr_signal_emit_safe(&pointer->wlr_pointer.events.axis, &event);
+	uint32_t seat_version = wl_seat_get_version(seat->wl_seat);
+	if (seat_version >= WL_POINTER_AXIS_VALUE120_SINCE_VERSION) {
+		struct wlr_event_pointer_axis_value120 event = {
+			.device = &pointer->input_device->wlr_input_device,
+			.delta = wl_fixed_to_double(value),
+			.delta_value120 = pointer->axis_value120,
+			.orientation = axis,
+			.time_msec = time,
+			.source = pointer->axis_source,
+		};
+		wlr_signal_emit_safe(&pointer->wlr_pointer.events.axis_value120, &event);
+	} else {
+		struct wlr_event_pointer_axis event = {
+			.device = &pointer->input_device->wlr_input_device,
+			.delta = wl_fixed_to_double(value),
+			.delta_discrete = pointer->axis_discrete,
+			.orientation = axis,
+			.time_msec = time,
+			.source = pointer->axis_source,
+		};
+		wlr_signal_emit_safe(&pointer->wlr_pointer.events.axis, &event);
+	}
 
 	pointer->axis_discrete = 0;
 }
@@ -194,6 +207,17 @@ static void pointer_handle_axis_discrete(void *data,
 	pointer->axis_discrete = discrete;
 }
 
+static void pointer_handle_axis_value120(void *data, struct wl_pointer *wl_pointer,
+		uint32_t axis, int32_t value120) {
+	struct wlr_wl_seat *seat = data;
+	struct wlr_wl_pointer *pointer = seat->active_pointer;
+	if (pointer == NULL) {
+		return;
+	}
+
+	pointer->axis_value120 = value120;
+}
+
 static const struct wl_pointer_listener pointer_listener = {
 	.enter = pointer_handle_enter,
 	.leave = pointer_handle_leave,
@@ -204,6 +228,7 @@ static const struct wl_pointer_listener pointer_listener = {
 	.axis_source = pointer_handle_axis_source,
 	.axis_stop = pointer_handle_axis_stop,
 	.axis_discrete = pointer_handle_axis_discrete,
+	.axis_value120 = pointer_handle_axis_value120,
 };
 
 static void keyboard_handle_keymap(void *data, struct wl_keyboard *wl_keyboard,
diff --git a/include/backend/wayland.h b/include/backend/wayland.h
index 6f4fa201e..586e94a8d 100644
--- a/include/backend/wayland.h
+++ b/include/backend/wayland.h
@@ -101,6 +101,7 @@ struct wlr_wl_pointer {
 	struct zwp_relative_pointer_v1 *relative_pointer;
 	enum wlr_axis_source axis_source;
 	int32_t axis_discrete;
+	int32_t axis_value120;
 	struct wlr_wl_output *output;
 
 	struct wl_listener output_destroy;