Capturing text change events in a QComboBox

Question

I am developing a Qt application on Red Hat Linux. I want to capture Carriage Return key press events in a QComboBox.

I have connected a slot to the signal editTextChanged() which is emitted for every key press but not for the Enter Key.
Why so? Is there any other way to detect Carriage Returns?

Answer 1

I am assuming you wrote a slot and connected it to QComboBox::editTextChanged() signal.
This signal is fired when the text changes and Enter does not change the text, it accepts it. If you want to capture Carriage Return, there are a number of ways you can follow.

1. Subclass QComboBox.
   Override keyPressEvent() : first call QComboBox::keyPressEvent() and then check if the pressed key is Enter. If it is, emit a signal.
   Use this subclass whenever you need. Search about promoting widgets in QDesigner if you don't know how.

2. Implement a new class which inherits QObject. In this class, override eventFilter() : check if the event is a key press. If it is, check if it is the Enter key. If it is, emit a signal.
   Then, create an instance of this class and set it as event filter to your QComboBox. Connect a slot to this instance's signal, which you implemented.

If these are not clear, i recommend reading the following pages:

Using Custom Widgets with Qt designer

Qt Events & Event Filters

Answer 2

You could also look into the activated( const QString& ) signal. It might be emitted when the user hits enter.