Add support for system dark mode (Linux)

- Use `org.freedesktop.appearance color-scheme` to support system dark mode.

1 files changed, 59 insertions, 0 deletions

diff --git a/platform/linuxbsd/freedesktop_portal_desktop.h b/platform/linuxbsd/freedesktop_portal_desktop.h
new file mode 100644
index 0000000000..3d976b1ede
--- /dev/null
+++ b/platform/linuxbsd/freedesktop_portal_desktop.h
@@ -0,0 +1,59 @@
+/*************************************************************************/
+/*  freedesktop_portal_desktop.h                                         */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef FREEDESKTOP_PORTAL_DESKTOP_H
+#define FREEDESKTOP_PORTAL_DESKTOP_H
+
+#ifdef DBUS_ENABLED
+
+#include <stdint.h>
+
+class FreeDesktopPortalDesktop {
+private:
+	bool unsupported = false;
+
+	// Read a setting from org.freekdesktop.portal.Settings
+	bool read_setting(const char *p_namespace, const char *p_key, int p_type, void *r_value);
+
+public:
+	FreeDesktopPortalDesktop();
+
+	bool is_supported() { return !unsupported; }
+
+	// Retrieve the system's preferred color scheme.
+	// 0: No preference or unknown.
+	// 1: Prefer dark appearance.
+	// 2: Prefer light appearance.
+	uint32_t get_appearance_color_scheme();
+};
+
+#endif // DBUS_ENABLED
+
+#endif // FREEDESKTOP_PORTAL_DESKTOP_H