How do I create a custom slot in qt4 designer?

Question

I don't know how to do this. Whenever I use the signal/slot editor dialog box, I have to choose from the existing list of slots. So the question is how do I create a custom named slot? Thanks

Answer 1

Unfortunately this is not possible in Qt4.

In Qt3 you could create custom slots which where then implemented in the ui.h file. However, Qt4 does not use this file so custom slots are not supported.

There is some discussion of this issue over on QtForum

Answer 2

This doesn't seem to be possible in a simple way.

The designer only allows you to promote existing widgets to your own custom widgets. yet it doesn't allow you to connect the signals and slots of the class of promoted widgets.

The way this is possible is creating a plugin for the designer as is described here and in the pages that follow it.

The normal course of action is to promote a widget to your own class and then to connect it manually in your own code. this process is described here

Answer 3

It is not possible to do it, because it means you would add a slot to an existing Qt class like QPushButton which is not really the way to go.

You should create your own QWidget eventually by subclassing an existing one. Then integrating it into Qt Designer as a plugin as suggested. Having your own class allows you to add/modifiy the signals/slots available as you want.

Answer 4

Don't forget about the slot auto-connection features. There are a few drawbacks, like having to rename your function if you rename your widget, but we use those a lot at my company.

Answer 5

Yes it is possible now. New version of QtDesigner supports custom slots.

Answer 6

you can use the magic slot format of

void on_objectName_signal() {
// slot code here, where objectname is the Qt Designer object name
// and the signal is the emission
}

The connection to this method is established by the method connectSlotsByName and whenever the signal is emitted, this slot is invoked.

Answer 7

This does seem to be possible in the version of Qt Designer 4.5.2, but its can't be done from the Signal/Slot Editor dock-widget in the main window.

This is what worked for me

1. Switch to Edit Signals/Slots mode (F4)
2. Drag and drop from the widget which it to emit the signal, to the widget which is to receive the signal.
3. A Configure Connection dialog appears, showing the signals for the emitting widget, and the slots for the receiving widget. Click Edit... below the slots column on the right.
4. A Signals/Slots of ReceivingWidget dialog appears. In here its is possible to click the plus icon beneath slots to add a new slot of any name.
5. You can then go back and connect to your new slot in the Configure Connection dialog, or indeed in the Signal/Slot Editor dockwidget back in the main window.

Caveat: I'm using PyQt, and I've only tried to use slots added in this way from Python, not from C++, so your mileage may vary...