output: add present event

backend/drm/drm.c

@@ -1149,8 +1149,8 @@ void scan_drm_connectors(struct wlr_drm_backend *drm) {
 }
 
 static void page_flip_handler(int fd, unsigned seq,
-		unsigned tv_sec, unsigned tv_usec, void *user) {
+		unsigned tv_sec, unsigned tv_usec, void *data) {
-	struct wlr_drm_connector *conn = user;
+	struct wlr_drm_connector *conn = data;
 	struct wlr_drm_backend *drm =
 		get_drm_backend_from_backend(conn->output.backend);
 
@@ -1170,6 +1170,14 @@ static void page_flip_handler(int fd, unsigned seq,
 		post_drm_surface(&conn->crtc->primary->mgpu_surf);
 	}
 
+	struct timespec present_time = {
+		.tv_sec = tv_sec,
+		.tv_nsec = tv_usec * 1000,
+	};
+	uint32_t present_flags = WLR_OUTPUT_PRESENT_VSYNC |
+		WLR_OUTPUT_PRESENT_HW_CLOCK | WLR_OUTPUT_PRESENT_HW_COMPLETION;
+	wlr_output_send_present(&conn->output, &present_time, seq, present_flags);
+
 	if (drm->session->active) {
 		wlr_output_send_frame(&conn->output);
 	}

include/wlr/interfaces/wlr_output.h

@@ -45,5 +45,7 @@ void wlr_output_update_enabled(struct wlr_output *output, bool enabled);
 void wlr_output_update_needs_swap(struct wlr_output *output);
 void wlr_output_damage_whole(struct wlr_output *output);
 void wlr_output_send_frame(struct wlr_output *output);
+void wlr_output_send_present(struct wlr_output *output, struct timespec *when,
+	unsigned seq, uint32_t flags);
 
 #endif

include/wlr/types/wlr_output.h

@@ -91,6 +91,7 @@ struct wlr_output {
 		struct wl_signal frame;
 		struct wl_signal needs_swap;
 		struct wl_signal swap_buffers; // wlr_output_event_swap_buffers
+		struct wl_signal present; // wlr_output_event_present
 		struct wl_signal enable;
 		struct wl_signal mode;
 		struct wl_signal scale;
@@ -123,6 +124,19 @@ struct wlr_output_event_swap_buffers {
 	pixman_region32_t *damage;
 };
 
+enum wlr_output_present_flag {
+	WLR_OUTPUT_PRESENT_VSYNC = 0x1,
+	WLR_OUTPUT_PRESENT_HW_CLOCK = 0x2,
+	WLR_OUTPUT_PRESENT_HW_COMPLETION = 0x4,
+};
+
+struct wlr_output_event_present {
+	struct wlr_output *output;
+	struct timespec *when;
+	unsigned seq;
+	uint32_t flags; // enum wlr_output_present_flag
+};
+
 struct wlr_surface;
 
 /**

types/wlr_output.c

@@ -560,6 +560,17 @@ void wlr_output_schedule_frame(struct wlr_output *output) {
 		wl_event_loop_add_idle(ev, schedule_frame_handle_idle_timer, output);
 }
 
+void wlr_output_send_present(struct wlr_output *output, struct timespec *when,
+		unsigned seq, uint32_t flags) {
+	struct wlr_output_event_present event = {
+		.output = output,
+		.when = when,
+		.seq = seq,
+		.flags = flags,
+	};
+	wlr_signal_emit_safe(&output->events.present, &event);
+}
+
 bool wlr_output_set_gamma(struct wlr_output *output, size_t size,
 		const uint16_t *r, const uint16_t *g, const uint16_t *b) {
 	if (!output->impl->set_gamma) {