export-dmabuf: wait for the frame to be ready, send timestamp

include/wlr/types/wlr_export_dmabuf_v1.h

@@ -11,6 +11,8 @@ struct wlr_export_dmabuf_frame_v1 {
 	struct wl_list link;
 
 	struct wlr_output *output;
+
+	struct wl_listener output_swap_buffers;
 };
 
 struct wlr_export_dmabuf_manager_v1 {

include/wlr/types/wlr_output.h

@@ -82,7 +82,7 @@ struct wlr_output {
 	struct {
 		struct wl_signal frame;
 		struct wl_signal needs_swap;
-		struct wl_signal swap_buffers;
+		struct wl_signal swap_buffers; // wlr_output_event_swap_buffers
 		struct wl_signal enable;
 		struct wl_signal mode;
 		struct wl_signal scale;
@@ -108,6 +108,12 @@ struct wlr_output {
 	void *data;
 };
 
+struct wlr_output_event_swap_buffers {
+	struct wlr_output *output;
+	struct timespec *when;
+	pixman_region32_t *damage;
+};
+
 struct wlr_surface;
 
 void wlr_output_enable(struct wlr_output *output, bool enable);

types/wlr_export_dmabuf_v1.c

@@ -30,9 +30,25 @@ static const struct zwlr_export_dmabuf_frame_v1_interface frame_impl = {
 static void frame_handle_resource_destroy(struct wl_resource *resource) {
 	struct wlr_export_dmabuf_frame_v1 *frame = frame_from_resource(resource);
 	wl_list_remove(&frame->link);
+	wl_list_remove(&frame->output_swap_buffers.link);
 	free(frame);
 }
 
+static void frame_output_handle_swap_buffers(struct wl_listener *listener,
+		void *data) {
+	struct wlr_export_dmabuf_frame_v1 *frame =
+		wl_container_of(listener, frame, output_swap_buffers);
+	struct wlr_output_event_swap_buffers *event = data;
+
+	wl_list_remove(&frame->output_swap_buffers.link);
+	wl_list_init(&frame->output_swap_buffers.link);
+
+	uint32_t tv_sec_hi = event->when->tv_sec << 32;
+	uint32_t tv_sec_lo = event->when->tv_sec & 0xFFFFFFFF;
+	zwlr_export_dmabuf_frame_v1_send_ready(frame->resource,
+		tv_sec_hi, tv_sec_lo, event->when->tv_nsec);
+}
+
 
 static const struct zwlr_export_dmabuf_manager_v1_interface manager_impl;
 
@@ -87,7 +103,7 @@ static void manager_handle_capture_output(struct wl_client *client,
 
 	uint32_t frame_flags = 0;
 	uint32_t mod_high = attribs.modifier[0] >> 32;
-	uint32_t mod_low = attribs.modifier[0];
+	uint32_t mod_low = attribs.modifier[0] & 0xFFFFFFFF;
 
 	zwlr_export_dmabuf_frame_v1_send_frame(frame->resource,
 		output->width, output->height, output->scale, output->transform,
@@ -106,9 +122,8 @@ static void manager_handle_capture_output(struct wl_client *client,
 			attribs.offset[i], attribs.stride[i]);
 	}
 
-	// TODO: wait for the frame to be ready
-	// TODO: timestamps
-	zwlr_export_dmabuf_frame_v1_send_ready(frame->resource, 0, 0, 0);
+	frame->output_swap_buffers.notify = frame_output_handle_swap_buffers;
+	wl_signal_add(&output->events.swap_buffers, &frame->output_swap_buffers);
 }
 
 static const struct zwlr_export_dmabuf_manager_v1_interface manager_impl = {

types/wlr_output.c

@@ -467,7 +467,12 @@ bool wlr_output_swap_buffers(struct wlr_output *output, struct timespec *when,
 		output->idle_frame = NULL;
 	}
 
-	wlr_signal_emit_safe(&output->events.swap_buffers, damage);
+	struct wlr_output_event_swap_buffers event = {
+		.output = output,
+		.when = when,
+		.damage = damage,
+	};
+	wlr_signal_emit_safe(&output->events.swap_buffers, &event);
 
 	int width, height;
 	wlr_output_transformed_resolution(output, &width, &height);