Add C++20 RAII wrapper around wlroots 0.20 + scenefx

Wraps wlroots' C ABI behind owning types (Display, Backend, Compositor,
Output, XdgShell/Toplevel, Seat/Cursor/Keyboard, Scene/Node/Tree) with
wl_signal -> std::function callbacks. Links the scenefx effect engine and
ships a wlr::fx animation helper. Includes a runnable tinywl-style compositor
and a scene/blur demo.

License: AGPL-3.0-only.

include/wlr/compositor.hpp

@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+#pragma once
+
+#include "wlr/display.hpp"
+#include "wlr/signals.hpp"
+#include "wlr/scene.hpp"
+#include "wlr/node.hpp"
+#include "wlr/output.hpp"
+
+namespace wlr {
+
+class Renderer {
+public:
+	Renderer(struct wlr_renderer* r) : m_renderer(r) {}
+	struct wlr_renderer* raw() const { return m_renderer; }
+	explicit operator bool() const { return m_renderer != nullptr; }
+	bool init_wl_display(Display& d) { return wlr_renderer_init_wl_display(m_renderer, d.raw()); }
+	void destroy() { if (m_renderer) { wlr_renderer_destroy(m_renderer); m_renderer = nullptr; } }
+	~Renderer() { destroy(); }
+
+private:
+	struct wlr_renderer* m_renderer;
+};
+
+class Allocator {
+public:
+	Allocator(struct wlr_allocator* a) : m_allocator(a) {}
+	struct wlr_allocator* raw() const { return m_allocator; }
+	explicit operator bool() const { return m_allocator != nullptr; }
+	void destroy() { if (m_allocator) { wlr_allocator_destroy(m_allocator); m_allocator = nullptr; } }
+	~Allocator() { destroy(); }
+
+private:
+	struct wlr_allocator* m_allocator;
+};
+
+class DataDeviceManager {
+public:
+	DataDeviceManager(struct wlr_data_device_manager* m) : m_manager(m) {}
+	struct wlr_data_device_manager* raw() const { return m_manager; }
+
+private:
+	struct wlr_data_device_manager* m_manager;
+};
+
+class Compositor {
+public:
+	Compositor(Display& display, Renderer& renderer)
+		: m_compositor(wlr_compositor_create(display.raw(), 6, renderer.raw())) {}
+	struct wlr_compositor* raw() const { return m_compositor; }
+	explicit operator bool() const { return m_compositor != nullptr; }
+
+private:
+	struct wlr_compositor* m_compositor;
+};
+
+}