QAbstractNativeEventFilter Class Reference

\inmodule QtCore More...

#include <qabstractnativeeventfilter.h>

Inheritance diagram for QAbstractNativeEventFilter:

Collaboration diagram for QAbstractNativeEventFilter:

Public Member Functions
	QAbstractNativeEventFilter ()
	Creates a native event filter.
virtual	~QAbstractNativeEventFilter ()
	Destroys the native event filter.
virtual bool	nativeEventFilter (const QByteArray &eventType, void *message, qintptr *result)=0
	This method is called for every native event.

Detailed Description

\inmodule QtCore

Since

5.0

The QAbstractNativeEventFilter class provides an interface for receiving native events, such as MSG or XCB event structs.

Definition at line 13 of file qabstractnativeeventfilter.h.

Constructor & Destructor Documentation

QAbstractNativeEventFilter()

QAbstractNativeEventFilter::QAbstractNativeEventFilter

(

)

Creates a native event filter.

By default this doesn't do anything. Remember to install it on the application object.

Definition at line 24 of file qabstractnativeeventfilter.cpp.

References Q_UNUSED.

~QAbstractNativeEventFilter()

QAbstractNativeEventFilter::~QAbstractNativeEventFilter ( )

virtual

Destroys the native event filter.

This automatically removes it from the application.

Definition at line 34 of file qabstractnativeeventfilter.cpp.

References QAbstractEventDispatcher::instance(), and QAbstractEventDispatcher::removeNativeEventFilter().

Here is the call graph for this function:

Member Function Documentation

nativeEventFilter()

bool QAbstractNativeEventFilter::nativeEventFilter ( const QByteArray & eventType, void * message, qintptr * result )

pure virtual

This method is called for every native event.

Note

The filter function here receives native messages, for example, MSG or XCB event structs.

It is called by the QPA platform plugin. On Windows, it is called by the event dispatcher.

The type of event eventType is specific to the platform plugin chosen at run-time, and can be used to cast message to the right type.

On X11, eventType is set to "xcb_generic_event_t", and the message can be casted to a xcb_generic_event_t pointer.

On Windows, eventType is set to "windows_generic_MSG" for messages sent to toplevel windows, and "windows_dispatcher_MSG" for system-wide messages such as messages from a registered hot key. In both cases, the message can be casted to a MSG pointer. The result pointer is only used on Windows, and corresponds to the LRESULT pointer.

On macOS, eventType is set to "mac_generic_NSEvent", and the message can be casted to an NSEvent pointer.

In your reimplementation of this function, if you want to filter the message out, i.e. stop it being handled further, return true; otherwise return false.

{Linux example}

class MyXcbEventFilter : public QAbstractNativeEventFilter
{
public:
    bool nativeEventFilter(const QByteArray &eventType, void *message, qintptr *) override
    {
        if (eventType == "xcb_generic_event_t") {
            xcb_generic_event_t* ev = static_cast<xcb_generic_event_t *>(message);
            // ...
        }
        return false;
    }
};

{Windows example}

class MyMSGEventFilter : public QAbstractNativeEventFilter
{
public:
    bool nativeEventFilter(const QByteArray &eventType, void *message, qintptr *) override
    {
        if (eventType == "windows_generic_MSG") {
            MSG *msg = static_cast<MSG *>(message);
            // ...
        } else if (eventType == "windows_dispatcher_MSG") {
            MSG *msg = static_cast<MSG *>(message);
            // ...
        }
        return false;
    }
};

{macOS example}

mycocoaeventfilter.h:

#include <QAbstractNativeEventFilter>
 
class MyCocoaEventFilter : public QAbstractNativeEventFilter
{
public:
    bool nativeEventFilter(const QByteArray &eventType, void *message, qintptr *) override;
};

mycocoaeventfilter.mm:

#include "mycocoaeventfilter.h"
 
#import <AppKit/AppKit.h>
 
bool MyCocoaEventFilter::nativeEventFilter(const QByteArray &eventType, void *message, qintptr *)
{
    if (eventType == "mac_generic_NSEvent") {
        NSEvent *event = static_cast<NSEvent *>(message);
        if ([event type] == NSKeyDown) {
            // Handle key event
            qDebug() << QString::fromNSString([event characters]);
        }
    }
    return false;
}

myapp.pro:

HEADERS += mycocoaeventfilter.h
OBJECTIVE_SOURCES += mycocoaeventfilter.mm
LIBS += -framework AppKit

Implemented in QWindowsRemovableDriveListener, MyXcbEventFilter, MyCocoaEventFilter, MyMSGEventFilter, QBenchmarkEvent, and QQnxWindowGrabber.

---

The documentation for this class was generated from the following files:

• qtbase/src/corelib/kernel/qabstractnativeeventfilter.h (05fc3aef53348fb58be6308076e000825b704e58)
• qtbase/src/corelib/kernel/qabstractnativeeventfilter.cpp (aa694575331ea0bda30cb4cc76174ced4d20df89)