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| author | Shawn Rutledge <shawn.rutledge@qt.io> | 2019-12-23 11:17:08 +0100 |
|---|---|---|
| committer | Shawn Rutledge <shawn.rutledge@qt.io> | 2019-12-23 14:42:18 +0100 |
| commit | 46d1b5b5a9d8fd1fd6629afd67eec7b32fc840fc (patch) | |
| tree | daf94b985335639261d4ec9332da9079e3744a9c /src/qml/doc/src | |
| parent | de2f7ef280771df03398a375230cb42e23ae25d7 (diff) | |
doc: Clarify Q_GADGET limitations in Qt 5
Fixes: QTBUG-79640
Change-Id: I7c4377312a337ec5f65389dc4998f1df91e5f67c
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Diffstat (limited to 'src/qml/doc/src')
| -rw-r--r-- | src/qml/doc/src/cppintegration/data.qdoc | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/qml/doc/src/cppintegration/data.qdoc b/src/qml/doc/src/cppintegration/data.qdoc index 6bf7dbfb8f..7c2693508c 100644 --- a/src/qml/doc/src/cppintegration/data.qdoc +++ b/src/qml/doc/src/cppintegration/data.qdoc @@ -386,6 +386,14 @@ properties: Q_DECLARE_METATYPE(Actor) \endcode +The usual pattern is to use a gadget class as the type of a property, or to +emit a gadget as a signal argument. In such cases, the gadget instance is +passed by value between C++ and QML (because it's a value type). If QML code +changes a property of a gadget property, the entire gadget is re-created and +passed back to the C++ property setter. In Qt 5, gadget types cannot be +instantiated by direct declaration in QML. In contrast, a QObject instance can +be declared; and QObject instances are always passed by pointer from C++ to QML. + \section1 Enumeration Types To use a custom enumeration as a data type, its class must be registered and |