Access the owner JNI handle from property wrappers via a method

This matches the canonical interface all the QAndroidX types have in Qt.

autotests/jnipropertytest.cpp

@@ -24,7 +24,8 @@ class TestClass : android::content::Intent
     JNI_PROPERTY(int, myIntField)
     JNI_PROPERTY(android::net::Uri, myUriField)
 
-public:
+    inline QAndroidJniObject handle() const { return m_handle; }
+private:
     QAndroidJniObject m_handle;
 };
 
@@ -61,13 +62,13 @@ private Q_SLOTS:
         const QAndroidJniObject bla = obj.myUriField;
         obj.myUriField = bla;
 
-        QCOMPARE(obj.m_handle.protocol().size(), 6);
-        QCOMPARE(obj.m_handle.protocol().at(0), QLatin1String("getObjectField: myStringField Ljava/lang/String;"));
-        QCOMPARE(obj.m_handle.protocol().at(1), QLatin1String("setField: myStringField Ljava/lang/String;"));
-        QCOMPARE(obj.m_handle.protocol().at(2), QLatin1String("getField: myIntField I"));
-        QCOMPARE(obj.m_handle.protocol().at(3), QLatin1String("setField: myIntField I"));
-        QCOMPARE(obj.m_handle.protocol().at(4), QLatin1String("getObjectField: myUriField Landroid/net/Uri;"));
-        QCOMPARE(obj.m_handle.protocol().at(5), QLatin1String("setField: myUriField Landroid/net/Uri;"));
+        QCOMPARE(obj.handle().protocol().size(), 6);
+        QCOMPARE(obj.handle().protocol().at(0), QLatin1String("getObjectField: myStringField Ljava/lang/String;"));
+        QCOMPARE(obj.handle().protocol().at(1), QLatin1String("setField: myStringField Ljava/lang/String;"));
+        QCOMPARE(obj.handle().protocol().at(2), QLatin1String("getField: myIntField I"));
+        QCOMPARE(obj.handle().protocol().at(3), QLatin1String("setField: myIntField I"));
+        QCOMPARE(obj.handle().protocol().at(4), QLatin1String("getObjectField: myUriField Landroid/net/Uri;"));
+        QCOMPARE(obj.handle().protocol().at(5), QLatin1String("setField: myUriField Landroid/net/Uri;"));
 #endif
     }
 };

src/kandroidextras/jni/jniproperty.h

@@ -72,7 +72,7 @@ class PropertyBase {
 protected:
     inline QAndroidJniObject handle() const {
         const auto owner = reinterpret_cast<const ClassType*>(reinterpret_cast<const char*>(this) - OffsetHolder::offset());
-        return owner->m_handle;
+        return owner->handle();
     }
 };
 
@@ -167,6 +167,7 @@ public: \
 private: \
     struct _jni_ ## name ## __NameHolder { static constexpr const char* jniName() { return "" #name; } }; \
     struct _jni_ ## name ## __OffsetHolder { static constexpr std::size_t offset() { return offsetof(_jni_ThisType, name); } }; \
+    friend class KAndroidExtras::Jni::PropertyBase<_jni_ThisType, _jni_ ## name ## __OffsetHolder>; \
 public: \
     [[no_unique_address]] Jni::Property<type, _jni_ThisType, _jni_ ## name ## __NameHolder, _jni_ ## name ## __OffsetHolder, Jni::is_basic_type<type>::value> name;
 }