backend/wayland: add support for presentation-time

backend/wayland/backend.c

@@ -19,6 +19,7 @@
 #include "util/signal.h"
 #include "linux-dmabuf-unstable-v1-client-protocol.h"
 #include "pointer-gestures-unstable-v1-client-protocol.h"
+#include "presentation-time-client-protocol.h"
 #include "xdg-decoration-unstable-v1-client-protocol.h"
 #include "xdg-shell-client-protocol.h"
 #include "tablet-unstable-v2-client-protocol.h"
@@ -108,6 +109,9 @@ static void registry_global(void *data, struct wl_registry *registry,
 	} else if (strcmp(iface, zwp_pointer_gestures_v1_interface.name) == 0) {
 		wl->zwp_pointer_gestures_v1 = wl_registry_bind(registry, name,
 			&zwp_pointer_gestures_v1_interface, 1);
+	} else if (strcmp(iface, wp_presentation_interface.name) == 0) {
+		wl->presentation = wl_registry_bind(registry, name,
+			&wp_presentation_interface, 1);
 	} else if (strcmp(iface, zwp_tablet_manager_v2_interface.name) == 0) {
 		wl->tablet_manager = wl_registry_bind(registry, name,
 			&zwp_tablet_manager_v2_interface, 1);
@@ -202,6 +206,9 @@ static void backend_destroy(struct wlr_backend *backend) {
 	if (wl->zwp_pointer_gestures_v1) {
 		zwp_pointer_gestures_v1_destroy(wl->zwp_pointer_gestures_v1);
 	}
+	if (wl->presentation) {
+		wp_presentation_destroy(wl->presentation);
+	}
 	if (wl->zwp_linux_dmabuf_v1) {
 		zwp_linux_dmabuf_v1_destroy(wl->zwp_linux_dmabuf_v1);
 	}

backend/wayland/output.c

@@ -17,6 +17,7 @@
 #include "backend/wayland.h"
 #include "util/signal.h"
 #include "linux-dmabuf-unstable-v1-client-protocol.h"
+#include "presentation-time-client-protocol.h"
 #include "xdg-decoration-unstable-v1-client-protocol.h"
 #include "xdg-shell-client-protocol.h"
 
@@ -26,8 +27,6 @@ static struct wlr_wl_output *get_wl_output_from_output(
 	return (struct wlr_wl_output *)wlr_output;
 }
 
-static struct wl_callback_listener frame_listener;
-
 static void surface_frame_callback(void *data, struct wl_callback *cb,
 		uint32_t time) {
 	struct wlr_wl_output *output = data;
@@ -38,10 +37,60 @@ static void surface_frame_callback(void *data, struct wl_callback *cb,
 	wlr_output_send_frame(&output->wlr_output);
 }
 
-static struct wl_callback_listener frame_listener = {
+static const struct wl_callback_listener frame_listener = {
 	.done = surface_frame_callback
 };
 
+static void presentation_feedback_destroy(
+		struct wlr_wl_presentation_feedback *feedback) {
+	wl_list_remove(&feedback->link);
+	wp_presentation_feedback_destroy(feedback->feedback);
+	free(feedback);
+}
+
+static void presentation_feedback_handle_sync_output(void *data,
+		struct wp_presentation_feedback *feedback, struct wl_output *output) {
+	// This space is intentionally left blank
+}
+
+static void presentation_feedback_handle_presented(void *data,
+		struct wp_presentation_feedback *wp_feedback, uint32_t tv_sec_hi,
+		uint32_t tv_sec_lo, uint32_t tv_nsec, uint32_t refresh_ns,
+		uint32_t seq_hi, uint32_t seq_lo, uint32_t flags) {
+	struct wlr_wl_presentation_feedback *feedback = data;
+
+	struct timespec t = {
+		.tv_sec = ((uint64_t)tv_sec_hi << 32) | tv_sec_lo,
+		.tv_nsec = tv_nsec,
+	};
+	struct wlr_output_event_present event = {
+		.commit_seq = feedback->commit_seq,
+		.when = &t,
+		.seq = ((uint64_t)seq_hi << 32) | seq_lo,
+		.refresh = refresh_ns,
+		.flags = flags,
+	};
+	wlr_output_send_present(&feedback->output->wlr_output, &event);
+
+	presentation_feedback_destroy(feedback);
+}
+
+static void presentation_feedback_handle_discarded(void *data,
+		struct wp_presentation_feedback *wp_feedback) {
+	struct wlr_wl_presentation_feedback *feedback = data;
+
+	wlr_output_send_present(&feedback->output->wlr_output, NULL);
+
+	presentation_feedback_destroy(feedback);
+}
+
+static const struct wp_presentation_feedback_listener
+		presentation_feedback_listener = {
+	.sync_output = presentation_feedback_handle_sync_output,
+	.presented = presentation_feedback_handle_presented,
+	.discarded = presentation_feedback_handle_discarded,
+};
+
 static bool output_set_custom_mode(struct wlr_output *wlr_output,
 		int32_t width, int32_t height, int32_t refresh) {
 	struct wlr_wl_output *output = get_wl_output_from_output(wlr_output);
@@ -137,6 +186,12 @@ static bool output_commit(struct wlr_output *wlr_output) {
 		output->current_wl_buffer = NULL;
 	}
 
+	struct wp_presentation_feedback *wp_feedback = NULL;
+	if (output->backend->presentation != NULL) {
+		wp_feedback = wp_presentation_feedback(output->backend->presentation,
+			output->surface);
+	}
+
 	assert(wlr_output->pending.committed & WLR_OUTPUT_STATE_BUFFER);
 	switch (wlr_output->pending.buffer_type) {
 	case WLR_OUTPUT_STATE_BUFFER_RENDER:
@@ -167,8 +222,23 @@ static bool output_commit(struct wlr_output *wlr_output) {
 		break;
 	}
 
-	// TODO: if available, use the presentation-time protocol
+	if (wp_feedback != NULL) {
+		struct wlr_wl_presentation_feedback *feedback =
+			calloc(1, sizeof(*feedback));
+		if (feedback == NULL) {
+			wp_presentation_feedback_destroy(wp_feedback);
+			return false;
+		}
+		feedback->output = output;
+		feedback->feedback = wp_feedback;
+		feedback->commit_seq = output->wlr_output.commit_seq + 1;
+		wl_list_insert(&output->presentation_feedbacks, &feedback->link);
+
+		wp_presentation_feedback_add_listener(wp_feedback,
+			&presentation_feedback_listener, feedback);
+	} else {
 		wlr_output_send_present(wlr_output, NULL);
+	}
 
 	return true;
 }
@@ -267,6 +337,12 @@ static void output_destroy(struct wlr_output *wlr_output) {
 		wl_callback_destroy(output->frame_callback);
 	}
 
+	struct wlr_wl_presentation_feedback *feedback, *feedback_tmp;
+	wl_list_for_each_safe(feedback, feedback_tmp,
+			&output->presentation_feedbacks, link) {
+		presentation_feedback_destroy(feedback);
+	}
+
 	wlr_egl_destroy_surface(&output->backend->egl, output->egl_surface);
 	wl_egl_window_destroy(output->egl_window);
 	if (output->zxdg_toplevel_decoration_v1) {
@@ -383,6 +459,7 @@ struct wlr_output *wlr_wl_output_create(struct wlr_backend *wlr_backend) {
 		++backend->last_output_num);
 
 	output->backend = backend;
+	wl_list_init(&output->presentation_feedbacks);
 
 	output->surface = wl_compositor_create_surface(backend->compositor);
 	if (!output->surface) {

include/backend/wayland.h

@@ -35,6 +35,7 @@ struct wlr_wl_backend {
 	struct xdg_wm_base *xdg_wm_base;
 	struct zxdg_decoration_manager_v1 *zxdg_decoration_manager_v1;
 	struct zwp_pointer_gestures_v1 *zwp_pointer_gestures_v1;
+	struct wp_presentation *presentation;
 	struct zwp_linux_dmabuf_v1 *zwp_linux_dmabuf_v1;
 	struct zwp_relative_pointer_manager_v1 *zwp_relative_pointer_manager_v1;
 	struct wl_seat *seat;
@@ -46,6 +47,13 @@ struct wlr_wl_backend {
 	struct wlr_drm_format_set linux_dmabuf_v1_formats;
 };
 
+struct wlr_wl_presentation_feedback {
+	struct wlr_wl_output *output;
+	struct wl_list link;
+	struct wp_presentation_feedback *feedback;
+	uint32_t commit_seq;
+};
+
 struct wlr_wl_output {
 	struct wlr_output wlr_output;
 
@@ -61,6 +69,7 @@ struct wlr_wl_output {
 	EGLSurface egl_surface;
 	struct wl_buffer *pending_wl_buffer, *current_wl_buffer;
 	struct wlr_buffer *current_buffer;
+	struct wl_list presentation_feedbacks;
 
 	uint32_t enter_serial;
 

protocol/meson.build

@@ -41,6 +41,7 @@ protocols = [
 ]
 
 client_protocols = [
+	[wl_protocol_dir, 'stable/presentation-time/presentation-time.xml'],
 	[wl_protocol_dir, 'stable/xdg-shell/xdg-shell.xml'],
 	[wl_protocol_dir, 'unstable/idle-inhibit/idle-inhibit-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml'],