Qt：显示 QCompleter 时，eventFilter 未收到 KeyPress

Question

I have an subclassed QPlainTextEdit called Editor. The editor contains an object used to suggest text, called a Suggester. The user can press a button from the Suggester to show a QCompleter, the activeCompleter.

I need to mess with the activeCompleter when KeyPress events come in from the Editor, so in Suggester, I create an eventFilter and install it to the passed in Editor instance.

When the activeCompleter is not shown, the eventFilter receives the KeyPress events as expected. However, when the activeComplter is shown via activeComplter->complete(), the eventFilter does not recieve KeyPress events (the editor behaves however).

I don't understand why this is. The QCompleter is not a widget. The Editor retains focus. I do not intercept events or keys anywhere else.

Why is my eventFilter not receiving KeyPress events?

relevant code...

Editor::Editor(QWidget *parent) : QPlainTextEdit(parent){
    suggester = new Suggester(this);
}

Suggester::Suggester(Editor* editor){
    this->editor = editor;
    editor->installEventFilter(this);
}

bool Suggester::eventFilter(QObject *obj, QEvent *event){
    qDebug()<< "event filter of type " << event->type() << " from " << obj;
    return false;
}

Answer 1

It seems that your eventFilter member is incomplete. You have to filter the QEvent:KeyPress event as follows:

  bool Suggester::eventFilter(QObject *obj, QEvent *event)
  {
      if (obj == textEdit) {
          if (event->type() == QEvent::KeyPress) {
              QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
              qDebug() << "Ate key press" << keyEvent->key();
              return true;
          } else {
              return false;
          }
      } else {
          // pass the event on to the parent class
          return Suggester::eventFilter(obj, event);
      }
  }