QAbstractNativeEventFilter::nativeEventFilter not receiving DBT_DEVICEARRIVAL

[bhavyasg]

Hi All,

I am trying to get a USb insertion and removal event in a non-GUI class but with much success. I am not able to get the arrival and removal events. Can anyone lend some pointers. My code looks like -


Usbdetection.h
============

#ifndef USBDETECTION_H
#define USBDETECTION_H
 
#include <QAbstractNativeEventFilter>
#include <QProcess>
#include <QMap>
 
class UsbDetection : public QAbstractNativeEventFilter
{
 
public:
    UsbDetection();
    virtual bool nativeEventFilter(const QByteArray &eventType, void *message, long *) Q_DECL_OVERRIDE;
};
 
 
#endif // USBDETECTION_H

#ifndef USBDETECTION_H
#define USBDETECTION_H

#include <QAbstractNativeEventFilter>
#include <QProcess>
#include <QMap>

class UsbDetection : public QAbstractNativeEventFilter
{

public:
    UsbDetection();
    virtual bool nativeEventFilter(const QByteArray &eventType, void *message, long *) Q_DECL_OVERRIDE;
};


#endif // USBDETECTION_H

To copy to clipboard, switch view to plain text mode 

UsbDetection.cpp
=============

#include <QByteArray>
#include <windows.h>
#include <dbt.h>
#include "UsbDetection.h"
#include <QDebug>
#include <QDir>
 
UsbDetection::UsbDetection()
: QAbstractNativeEventFilter()
/*, mWmicProcess(new QProcess())
, mIsDevInsertion(FALSE)
, mDriveToDevNameMap(new QMap<QString, TDriveToMediaPair>())*/
{
    qDebug() << "In constructor()";
}
 
bool UsbDetection::nativeEventFilter(const QByteArray &eventType, void *pMessage, long* pResult) //Q_DECL_OVERRIDE
{
    qDebug() << " In native events" ;
    Q_UNUSED(eventType);
    Q_UNUSED(pResult);
 
    auto pWindowsMessage = static_cast<MSG*>(pMessage);
    auto wParam = pWindowsMessage->wParam;
    qDebug() << "wParam = " << wParam;
 
    if (wParam == DBT_DEVICEARRIVAL || wParam == DBT_DEVICEREMOVECOMPLETE) {
        qDebug() << "USB plug/unplug = " << wParam;
   ....................
 
    }
    return true;
}

#include <QByteArray>
#include <windows.h>
#include <dbt.h>
#include "UsbDetection.h"
#include <QDebug>
#include <QDir>

UsbDetection::UsbDetection()
: QAbstractNativeEventFilter()
/*, mWmicProcess(new QProcess())
, mIsDevInsertion(FALSE)
, mDriveToDevNameMap(new QMap<QString, TDriveToMediaPair>())*/
{
    qDebug() << "In constructor()";
}

bool UsbDetection::nativeEventFilter(const QByteArray &eventType, void *pMessage, long* pResult) //Q_DECL_OVERRIDE
{
    qDebug() << " In native events" ;
    Q_UNUSED(eventType);
    Q_UNUSED(pResult);

    auto pWindowsMessage = static_cast<MSG*>(pMessage);
    auto wParam = pWindowsMessage->wParam;
    qDebug() << "wParam = " << wParam;

    if (wParam == DBT_DEVICEARRIVAL || wParam == DBT_DEVICEREMOVECOMPLETE) {
        qDebug() << "USB plug/unplug = " << wParam;
   ....................
 
    }
    return true;
}

To copy to clipboard, switch view to plain text mode 

main.cpp
========

#include <QApplication>
 
#include <QDebug>
#include <QDir>
#include <QAbstractEventDispatcher>
 
#include "UsbDetection.h"
 
int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);
 
    UsbDetection UsbDetection;
    app.installNativeEventFilter(&UsbDetection);
    return app.exec();
}

#include <QApplication>

#include <QDebug>
#include <QDir>
#include <QAbstractEventDispatcher>

#include "UsbDetection.h"

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    UsbDetection UsbDetection;
    app.installNativeEventFilter(&UsbDetection);
    return app.exec();
}

To copy to clipboard, switch view to plain text mode 

Output :
=======
In constructor()
In native events
wParam = 0
In native events
wParam = 0
In native events
wParam = 0
In native events
wParam = 0

[anda_skoa]

Are you sure your application will work at all with you filtering away all native events?

Cheers,
_

[bhavyasg]

This app is required just to put divide USB events. I am not directing anything else from the app. Is that what you wanted to know?

[anda_skoa]

What i mean is: you are obviously getting native events but you filter them out.
Are you sure the base implementation in QCoreApplication doesn't need them?

Cheers,
_

[bhavyasg]

if you are talking about the return value from nativeEvent, then I have tried with false. But I still don't get the usb insertion/removal events

[anda_skoa]

Hmm, then maybe it is necessary to register for these events by calling some Windows API?

Also maybe check if libusb can deliver those notifications or if using a Qt hardware managemenSolid is a workable option.

Cheers,
_