QML: Allow namespaces as extensions to types

This way we can access the enums of namespaces as properties of the
primary type. This is achieved by:

1. Making enums of extended types available in the base type
2. Allowing the extension to be specified as plain metaObject rather
   than as type name.
3. Refraining from creating the extension if the create function does
   not exist.

The goal of this is to declare the Qt namespace in a civilized way, but
will also help with cleaning up the QtQuick value types and their enums.

Change-Id: I13399741d30ce38d1bff753cfa1b11e72ccfbf6a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 19 insertions, 5 deletions

diff --git a/src/qml/doc/src/qmlfunctions.qdoc b/src/qml/doc/src/qmlfunctions.qdoc
index c0c481b861..caca58f34a 100644
--- a/src/qml/doc/src/qmlfunctions.qdoc
+++ b/src/qml/doc/src/qmlfunctions.qdoc
@@ -230,10 +230,24 @@
   \relates QQmlEngine
 
   Declares that the enclosing type uses \a EXTENDED_TYPE as an extension to
-  provide further properties and methods in QML. This takes effect if the type
+  provide further properties, methods, and enumerations in QML. This takes
+  effect if the type is exposed to QML using a \l QML_ELEMENT or
+  \l QML_NAMED_ELEMENT() macro.
+
+  \sa QML_ELEMENT, QML_NAMED_ELEMENT(), QML_EXTENDED_NAMEPSACE(),
+      {Registering Extension Objects}
+*/
+
+/*!
+  \macro QML_EXTENDED_NAMESPACE(EXTENDED_NAMESPACE)
+  \relates QQmlEngine
+
+  Declares that the enclosing type uses \a EXTENDED_NAMESPACE as an extension to
+  provide further enumerations in QML. This takes effect if the type
   is exposed to QML using a \l QML_ELEMENT or \l QML_NAMED_ELEMENT() macro.
 
-  \sa QML_ELEMENT, QML_NAMED_ELEMENT(), {Registering Extension Objects}
+  \sa QML_ELEMENT, QML_NAMED_ELEMENT(), QML_EXTENDED(),
+      {Registering Extension Objects}
 */
 
 /*!
@@ -243,9 +257,9 @@
   Declares that any \l QML_ELEMENT, \l QML_NAMED_ELEMENT(), \l QML_ANONYMOUS,
   \l QML_INTERFACE, \l QML_UNCREATABLE(), \l QML_SINGLETON,
   \l QML_ADDED_IN_MINOR_VERSION(), \l QML_REMOVED_IN_MINOR_VERSION(),
-  \l QML_ATTACHED(), or \l QML_EXTENDED() macros in the enclosing C++ type do
-  not apply to the enclosing type but instead to \a FOREIGN_TYPE. The enclosing
-  type still needs to be registered with the
+  \l QML_ATTACHED(), \l QML_EXTENDED(), or \l  QML_EXTENDED_NAMESPACE() macros
+  in the enclosing C++ type do not apply to the enclosing type but instead to
+  \a FOREIGN_TYPE. The enclosing type still needs to be registered with the
   \l {The Meta-Object System}{meta object system} using a \l Q_GADGET or
   \l Q_OBJECT macro.