Lua: Add Lua plugin support

Adds basic support for writing Plugins using the lua scripting language.
Lua Plugins are registered just as native plugins are and can be enabled
or disabled via the plugin dialog.

see src/plugins/lua/README.md for further details.

Change-Id: I9f4d15e9632c46e1c6c132bcd0bbcdd70b150640
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/lua/luauibindings.cpp

@@ -0,0 +1,141 @@
+
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include "luaengine.h"
+#include "luaqttypes.h"
+
+#include <QMetaProperty>
+
+#include <QDialog>
+
+namespace Lua::Internal {
+
+template<class T = QObject>
+sol::object qobject_index_get(sol::this_state s, QObject *obj, const char *key)
+{
+    auto &metaObject = T::staticMetaObject;
+    int iProp = metaObject.indexOfProperty(key);
+    if (iProp != -1) {
+        QMetaProperty p = metaObject.property(iProp);
+
+        if (p.isEnumType()) {
+            int v = p.read(obj).toInt();
+            return sol::make_object(s.lua_state(), p.enumerator().valueToKey(v));
+        }
+
+#define LUA_VALUE_FROM_PROPERTY(VARIANT_TYPE, TYPE) \
+    case VARIANT_TYPE: { \
+        TYPE r = qvariant_cast<TYPE>(p.read(obj)); \
+        return sol::make_object(s.lua_state(), r); \
+    }
+
+        switch (p.type()) {
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::Rect, QRect)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::Size, QSize)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::Point, QPoint)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::RectF, QRectF)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::SizeF, QSizeF)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::PointF, QPointF)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::Color, QColor)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::Bool, bool)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::Int, int)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::Double, double)
+            LUA_VALUE_FROM_PROPERTY(QVariant::Type::String, QString)
+        default:
+            break;
+        }
+    }
+
+    for (int i = 0; i < metaObject.methodCount(); i++) {
+        QMetaMethod method = metaObject.method(i);
+        if (method.methodType() != QMetaMethod::Signal && method.name() == key) {
+            if (method.parameterCount() == 0) {
+                return sol::make_object(s.lua_state(),
+                                        [obj, i]() { obj->metaObject()->method(i).invoke(obj); });
+            }
+        }
+    }
+
+    return sol::lua_nil;
+}
+
+template<class T>
+void qobject_index_set(QObject *obj, const char *key, sol::stack_object value)
+{
+    auto &metaObject = T::staticMetaObject;
+    int iProp = metaObject.indexOfProperty(key);
+    if (iProp == -1)
+        return;
+
+    QMetaProperty p = metaObject.property(iProp);
+
+    if (p.isEnumType()) {
+        int v = p.enumerator().keyToValue(value.as<const char *>());
+        p.write(obj, v);
+    } else {
+#define SET_PROPERTY_FROM_LUA(VARIANT_TYPE, TYPE) \
+    case VARIANT_TYPE: { \
+        TYPE r = value.as<TYPE>(); \
+        p.write(obj, QVariant::fromValue(r)); \
+        break; \
+    }
+
+        switch (p.type()) {
+            SET_PROPERTY_FROM_LUA(QVariant::Type::Rect, QRect)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::Size, QSize)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::Point, QPoint)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::RectF, QRectF)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::SizeF, QSizeF)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::PointF, QPointF)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::Color, QColor)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::Bool, bool)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::Int, int)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::Double, double)
+            SET_PROPERTY_FROM_LUA(QVariant::Type::String, QString)
+        default:
+            break;
+        }
+    }
+}
+
+template<class T>
+size_t qobject_index_size(QObject *obj)
+{
+    return 0;
+}
+
+template<class T, class... Bases>
+sol::usertype<T> runtimeObject(sol::state_view lua)
+{
+    auto &metaObject = T::staticMetaObject;
+    auto className = metaObject.className();
+
+    return lua.new_usertype<T>(
+        className,
+        sol::call_constructor,
+        sol::constructors<T>(),
+        sol::meta_function::index,
+        [](sol::this_state s, T *obj, const char *key) { return qobject_index_get<T>(s, obj, key); },
+        sol::meta_function::new_index,
+        [](T *obj, const char *key, sol::stack_object value) {
+            qobject_index_set<T>(obj, key, value);
+        },
+        sol::meta_function::length,
+        [](T *obj) { return qobject_index_size<T>(obj); },
+        sol::base_classes,
+        sol::bases<Bases...>());
+}
+
+void registerUiBindings()
+{
+    LuaEngine::registerProvider("Qt.Gui", [](sol::state_view lua) {
+        runtimeObject<QObject>(lua);
+        runtimeObject<QWidget, QObject>(lua);
+        runtimeObject<QDialog, QWidget, QObject>(lua);
+
+        return sol::object{};
+    });
+}
+
+} // namespace Lua::Internal