Some questions about nativeEnentFilter using window messages

Ming_tft

Hello，I was working on a borderless window project recently, and there were some problems when using nativeEventFilter. When I received the message from windows in the nativeEventFilter function, the returned WM_NCCALCSIZE message was filtered, and then the border of my main window disappeared automatically. , I can’t find out what is causing the problem. Please help analyze why this is the case. I didn’t set FramelessWindowHint in my original window.

main.cpp

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    FFTMainWindow w;
    w.show();

    NativeEventHelper helper(&w);
    // helper = new NativeEventHelper(w);
    a.installNativeEventFilter(&helper);

    return a.exec();
}

NativeEventHelper.cpp

bool NativeEventHelper::nativeEventFilter(const QByteArray &eventType, void *message, long *result)
{
#ifdef Q_OS_WIN
    if (eventType != "windows_generic_MSG")
        return false;

    MSG* msg = static_cast<MSG*>(message);
    QWidget* widget = QWidget::find(reinterpret_cast<WId>(msg->hwnd));
    // qDebug()<<"----widget----"<<widget;
    if (!widget)
        return false;

    switch (msg->message) {

    case WM_NCCALCSIZE: {
        qDebug()<<"----WM_NCCALCSIZE----";
        *result = 0;
        return true;
    }
    default:
        break;
#endif

return QWidget::nativeEvent(eventType, message, result);
}

Christian Ehrlicher

@Ming_tft said in Some questions about nativeEnentFilter using window messages:

case WM_NCCALCSIZE: {
    qDebug()<<"----WM_NCCALCSIZE----";
    *result = 0;
    return true;

the returned WM_NCCALCSIZE message was filtered, and then the border of my main window disappeared automatically. , I can’t find out what is causing the problem.

You tell the caller that WM_NCCALCSIZE should be filtered.

Ming_tft

@Christian-Ehrlicher Thank you for your reply, it is helpful to me. In addition, I would like to ask another question. If I want to filter this way, I only want the main window to receive messages, but I don't want the child window control QWidget to receive messages. Can this be achieved? Or can it only be achieved by overloading the nativeEvent function on QMainWindow? Hope your reply