From 8eb7ec53d4333369e491d723840ca63e1351d1f2 Mon Sep 17 00:00:00 2001
From: Alexander Orzechowski <orzechowski.alexander@gmail.com>
Date: Sun, 7 Aug 2022 20:13:30 -0400
Subject: [PATCH] scene_graph: Introduce sway_scene_descriptor

Across a wayland compositor, there are multiple shells: It can be
a toplevel, or a layer_shell, or even something more meta like a drag
icon or highlight indicators when dragging windows around.

This object lets us store values that represent these modes of operation
and keep track of what object is being represented.
---
 include/sway/scene_descriptor.h | 19 +++++++++++++++++++
 sway/meson.build                |  1 +
 sway/scene_descriptor.c         | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+)
 create mode 100644 include/sway/scene_descriptor.h
 create mode 100644 sway/scene_descriptor.c

diff --git a/include/sway/scene_descriptor.h b/include/sway/scene_descriptor.h
new file mode 100644
index 000000000..a37633cc8
--- /dev/null
+++ b/include/sway/scene_descriptor.h
@@ -0,0 +1,19 @@
+#ifndef _SWAY_SCENE_DESCRIPTOR_H
+#define _SWAY_SCENE_DESCRIPTOR_H
+#include <wlr/types/wlr_scene.h>
+
+enum sway_scene_descriptor_type {
+};
+
+struct sway_scene_descriptor {
+	struct wlr_scene_node *node;
+	enum sway_scene_descriptor_type type;
+	void *data;
+
+	struct wl_listener destroy;
+};
+
+void scene_descriptor_assign(struct wlr_scene_node *node,
+	enum sway_scene_descriptor_type type, void *data);
+
+#endif
diff --git a/sway/meson.build b/sway/meson.build
index 4d7dccfa8..206bd638e 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -8,6 +8,7 @@ sway_sources = files(
 	'lock.c',
 	'main.c',
 	'realtime.c',
+	'scene_descriptor.c',
 	'server.c',
 	'swaynag.c',
 	'xdg_activation_v1.c',
diff --git a/sway/scene_descriptor.c b/sway/scene_descriptor.c
new file mode 100644
index 000000000..18710dbd7
--- /dev/null
+++ b/sway/scene_descriptor.c
@@ -0,0 +1,33 @@
+#include <stdlib.h>
+#include "log.h"
+#include "sway/scene_descriptor.h"
+
+static void handle_destroy(struct wl_listener *listener, void *data) {
+	struct sway_scene_descriptor *desc =
+		wl_container_of(listener, desc, destroy);
+
+	desc->node->data = NULL;
+	wl_list_remove(&desc->destroy.link);
+
+	free(desc);
+}
+
+void scene_descriptor_assign(struct wlr_scene_node *node,
+		enum sway_scene_descriptor_type type, void *data) {
+	struct sway_scene_descriptor *desc =
+		calloc(1, sizeof(struct sway_scene_descriptor));
+
+	if (!desc) {
+		sway_log(SWAY_ERROR, "Could not allocate a scene descriptor");
+		return;
+	}
+
+	desc->type = type;
+	desc->data = data;
+	desc->node = node;
+
+	desc->destroy.notify = handle_destroy;
+	wl_signal_add(&node->events.destroy, &desc->destroy);
+
+	node->data = desc;
+}