問題描述

我想知道 USB 設(shè)備何時連接到運行我的 Qt 應(yīng)用程序的計算機(在 Windows 中).在我的主要 QWidget 中，我重新實現(xiàn)了 winEventFilter，如下所示:

I want to know when a USB device is connected to the computer that my Qt application is running on (in Windows). In my main QWidget, I've reimplemented winEventFilter like this:

bool winEventFilter ( MSG * msg, long * result ) {
    qDebug() << msg;
    return false;
}

當(dāng)我連接 USB 設(shè)備時，我希望 qDebug 至少發(fā)送一些東西，但我什么也沒收到.

I'd expect qDebug to send at least something when I connect a USB device, but I don't get anything.

我猜我從根本上誤解了這里的過程 - 這是我的第一個 Qt 應(yīng)用程序！

I'm guessing that I'm fundamentally misunderstanding the process here - this is my first Qt app!

推薦答案

我相信您可能缺少的是注冊設(shè)備通知的調(diào)用.這是我用來做同樣事情的代碼，雖然我覆蓋了 QWidget 類的 winEvent() 方法而不是 winEventFilter.

I believe what you may be missing is the call to register for device notification. Here is code that I use to do the same thing, though I override the winEvent() method of the QWidget class and not the winEventFilter.

// Register for device connect notification
DEV_BROADCAST_DEVICEINTERFACE devInt;
ZeroMemory( &devInt, sizeof(devInt) );
devInt.dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);
devInt.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
devInt.dbcc_classguid = GUID_DEVINTERFACE_VOLUME;

m_hDeviceNotify =
    RegisterDeviceNotification( winId(), &devInt, DEVICE_NOTIFY_WINDOW_HANDLE );   
if(m_hDeviceNotify == NULL)
{
    qDebug() << "Failed to register device notification";
} // end if

注意:您很可能需要更改 DEV_BROADCAST_DEVICEINTERFACE 的值以滿足您的需要.

NOTE: You will most likely need to change the values of the DEV_BROADCAST_DEVICEINTERFACE to fit your needs.

要使用此代碼，您需要包含正確的頭文件并執(zhí)行正確的設(shè)置.DEV_BROADCAST_DEVICEINTERFACE 需要包含 Dbt.h 標(biāo)頭.此外，此代碼的重點是 RegisterDeviceNotification 函數(shù).信息可在 MSDN

To use this code you will need to include the proper header files and perform the proper setup. DEV_BROADCAST_DEVICEINTERFACE requires the Dbt.h header to be included. Also, the focal point of this code is on the RegisterDeviceNotification function. Info is available on MSDN

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