From 0aa7b835086218ea93bfc0da2526c728102d6771 Mon Sep 17 00:00:00 2001
From: Ruslan Kabatsayev <b7.10110111@gmail.com>
Date: Thu, 6 Jul 2023 01:18:32 +0400
Subject: [PATCH] Fix behavior of DitheringMode with QVariant in Qt5

Fixes #3304
---
 src/core/Dithering.hpp | 11 +++++++++++
 src/core/StelCore.cpp  |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/src/core/Dithering.hpp b/src/core/Dithering.hpp
index de4d60ff992df..3eb0af982cf8e 100644
--- a/src/core/Dithering.hpp
+++ b/src/core/Dithering.hpp
@@ -37,6 +37,17 @@ enum class DitheringMode
 	Color888,    //!< 24-bit color (AKA True color)
 	Color101010, //!< 30-bit color (AKA Deep color)
 };
+#if QT_VERSION < QT_VERSION_CHECK(5,14,0)
+// A similar pair of methods but templated for arbitrary enum first appears in Qt 5.14
+inline QDataStream& operator>>(QDataStream& s, DitheringMode& m)
+{
+	return s >> reinterpret_cast<std::underlying_type<DitheringMode>::type&>(m);
+}
+inline QDataStream& operator<<(QDataStream &s, const DitheringMode &m)
+{
+	return s << static_cast<typename std::underlying_type<DitheringMode>::type>(m);
+}
+#endif
 
 Vec3f calcRGBMaxValue(DitheringMode mode);
 
diff --git a/src/core/StelCore.cpp b/src/core/StelCore.cpp
index dc1752e16fe98..d3a630df79015 100644
--- a/src/core/StelCore.cpp
+++ b/src/core/StelCore.cpp
@@ -2056,6 +2056,7 @@ void StelCore::registerMathMetaTypes()
 	qRegisterMetaType<Mat4f>();
 	qRegisterMetaType<Mat3d>();
 	qRegisterMetaType<Mat3f>();
+	qRegisterMetaType<DitheringMode>();
 
 #if (QT_VERSION<QT_VERSION_CHECK(6,0,0))
 	//registers the QDataStream operators, so that QVariants with these types can be saved
@@ -2072,6 +2073,7 @@ void StelCore::registerMathMetaTypes()
 	qRegisterMetaTypeStreamOperators<Mat4f>();
 	qRegisterMetaTypeStreamOperators<Mat3d>();
 	qRegisterMetaTypeStreamOperators<Mat3f>();
+	qRegisterMetaTypeStreamOperators<DitheringMode>();
 #endif
 	//for debugging QVariants with these types, it helps if we register the string converters
 	// This is also required for QJSEngine.