Improve presentation-time API

include/wlr/types/wlr_presentation_time.h

@@ -14,6 +14,9 @@
 #include <time.h>
 #include <wayland-server-core.h>
 
+struct wlr_output;
+struct wlr_output_event_present;
+
 struct wlr_presentation {
 	struct wl_global *global;
 	struct wl_list resources; // wl_resource_get_link
@@ -28,20 +31,31 @@ struct wlr_presentation {
 };
 
 struct wlr_presentation_feedback {
-	struct wl_resource *resource;
 	struct wlr_presentation *presentation;
-	struct wlr_surface *surface;
+	struct wlr_surface *surface; // NULL if the surface has been destroyed
 	struct wl_list link; // wlr_presentation::feedbacks
 
+	struct wl_list resources; // wl_resource_get_link
+
 	// The surface contents were committed.
 	bool committed;
 	// The surface contents were sampled by the compositor and are to be
 	// presented on the next flip. Can become true only after committed becomes
 	// true.
 	bool sampled;
+	bool presented;
+
+	// Only when the wlr_presentation_surface_sampled_on_output helper has been
+	// called
+	struct wlr_output *output;
+	bool output_committed;
+	uint32_t output_commit_seq;
 
 	struct wl_listener surface_commit;
 	struct wl_listener surface_destroy;
+	struct wl_listener output_commit;
+	struct wl_listener output_present;
+	struct wl_listener output_destroy;
 };
 
 struct wlr_presentation_event {
@@ -58,10 +72,43 @@ struct wlr_backend;
 struct wlr_presentation *wlr_presentation_create(struct wl_display *display,
 	struct wlr_backend *backend);
 void wlr_presentation_destroy(struct wlr_presentation *presentation);
-void wlr_presentation_send_surface_presented(
-	struct wlr_presentation *presentation, struct wlr_surface *surface,
-	struct wlr_presentation_event *event);
-void wlr_presentation_surface_sampled(
+/**
+ * Mark the current surface's buffer as sampled.
+ *
+ * The compositor must call this function when it uses the surface's current
+ * contents (e.g. when rendering the surface's current texture, when
+ * referencing its current buffer, or when directly scanning out its current
+ * buffer). A wlr_presentation_feedback is returned. The compositor should call
+ * wlr_presentation_feedback_send_presented if this content has been displayed,
+ * then wlr_presentation_feedback_destroy.
+ *
+ * NULL is returned if the client hasn't requested presentation feedback for
+ * this surface.
+ */
+struct wlr_presentation_feedback *wlr_presentation_surface_sampled(
 	struct wlr_presentation *presentation, struct wlr_surface *surface);
+void wlr_presentation_feedback_send_presented(
+	struct wlr_presentation_feedback *feedback,
+	struct wlr_presentation_event *event);
+void wlr_presentation_feedback_destroy(
+	struct wlr_presentation_feedback *feedback);
+
+/**
+ * Fill a wlr_presentation_event from a wlr_output_event_present.
+ */
+void wlr_presentation_event_from_output(struct wlr_presentation_event *event,
+		const struct wlr_output_event_present *output_event);
+
+/**
+ * Mark the current surface's buffer as sampled on the given output.
+ *
+ * Instead of calling wlr_presentation_surface_sampled and managing the
+ * wlr_presentation_feedback itself, the compositor can call this function
+ * before a wlr_output_commit call to indicate that the surface's current
+ * contents will be displayed on the output.
+ */
+void wlr_presentation_surface_sampled_on_output(
+	struct wlr_presentation *presentation, struct wlr_surface *surface,
+	struct wlr_output *output);
 
 #endif

types/wlr_output.c

@@ -495,13 +495,14 @@ bool wlr_output_commit(struct wlr_output *output) {
 		wlr_surface_send_frame_done(cursor->surface, &now);
 	}
 
+	output->commit_seq++;
+
 	wlr_signal_emit_safe(&output->events.commit, output);
 
 	output->frame_pending = true;
 	output->needs_frame = false;
 	output_state_clear(&output->pending);
 	pixman_region32_clear(&output->damage);
-	output->commit_seq++;
 	return true;
 }
 
@@ -569,7 +570,7 @@ void wlr_output_send_present(struct wlr_output *output,
 	struct wlr_output_event_present _event = {0};
 	if (event == NULL) {
 		event = &_event;
-		event->commit_seq = output->commit_seq;
+		event->commit_seq = output->commit_seq + 1;
 	}
 
 	event->output = output;