Add support for platform plugin specific event filters.

The setEventFilter on the platform native interface allows subscribing to
events on the backend by event name.

Change-Id: Ib10077fbc69f0207edbae1177e7bbd18c8d0f9ae
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>
Reviewed-by: Michalina Ziemba <michalina.ziemba@nokia.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/src/gui/kernel/qplatformnativeinterface_qpa.cpp b/src/gui/kernel/qplatformnativeinterface_qpa.cpp
index f9ddd1f72a..626f6a1e51 100644
--- a/src/gui/kernel/qplatformnativeinterface_qpa.cpp
+++ b/src/gui/kernel/qplatformnativeinterface_qpa.cpp
@@ -106,4 +106,51 @@ void QPlatformNativeInterface::setWindowProperty(QPlatformWindow *window, const
     Q_UNUSED(value);
 }
 
+/*!
+    \typedef QPlatformNativeInterface::EventFilter
+    \since 5.0
+
+    A function with the following signature that can be used as an
+    event filter:
+
+    \code
+    bool myEventFilter(void *message, long *result);
+    \endcode
+
+    \sa setEventFilter()
+*/
+
+/*!
+    \fn EventFilter QPlatformNativeInterface::setEventFilter(const QByteArray &eventType, EventFilter filter)
+    \since 5.0
+
+    Replaces the event filter function for the native interface with
+    \a filter and returns the pointer to the replaced event filter
+    function. Only the current event filter function is called. If you
+    want to use both filter functions, save the replaced EventFilter
+    in a place where you can call it from.
+
+    The event filter function set here is called for all messages
+    received from the platform if they are given type \eventType.
+    It is \i not called for messages that are not meant for Qt objects.
+
+    The type of event is specific to the platform plugin chosen at run-time.
+
+    The event filter function should return \c true if the message should
+    be filtered, (i.e. stopped). It should return \c false to allow
+    processing the message to continue.
+
+    By default, no event filter function is set. For example, this function
+    returns a null EventFilter the first time it is called.
+
+    \note The filter function here receives native messages,
+    for example, MSG or XEvent structs. It is called by the platform plugin.
+*/
+QPlatformNativeInterface::EventFilter QPlatformNativeInterface::setEventFilter(const QByteArray &eventType, QPlatformNativeInterface::EventFilter filter)
+{
+    Q_UNUSED(eventType);
+    Q_UNUSED(filter);
+    return 0;
+}
+
 QT_END_NAMESPACE