MyXcbEventFilter Class Reference

[0] More...

Inheritance diagram for MyXcbEventFilter:

Collaboration diagram for MyXcbEventFilter:

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

Detailed Description

[0]

Definition at line 5 of file src_corelib_kernel_qabstractnativeeventfilter.cpp.

Member Function Documentation

nativeEventFilter()

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

inlineoverridevirtual

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

Implements QAbstractNativeEventFilter.

Definition at line 8 of file src_corelib_kernel_qabstractnativeeventfilter.cpp.

---

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

• qtbase/src/corelib/doc/snippets/code/src_corelib_kernel_qabstractnativeeventfilter.cpp (05fc3aef53348fb58be6308076e000825b704e58)