Qt Designer中的自定义菜单操作

Question

I'm currently trying to use Qt Designer to build a GUI and I would like to customize slots of my menu actions.

Eg: I'd like the user to press a menu action and it'd show a widget if it is hidden or hide it if it is already visible.

Basically, what I want to do is execute some code of mine and not the default actions such as show() or hide().

So I'm wondering if I should create a subclass of QMenuBar, add custom slots to it, then create a plugin to use it inside Qt Designer or if I should create a subclass for QMenu or QAction ? Or maybe it isn't the right way to do that ?

I'm working under Visual Studio and I'm only using Qt Designer, not Qt creator.

I'm new to GUI and Qt programming and I'm a bit lost here.

Thanks in advance :)

Answer 1

You have basically 2 options:

1. Implement the custom logic in the Mainwindow sublcass.
   For this, you simply add the slots required for your handling in the class, and make them available in Qt Designer. You can do this:
   either in the Signal/Slot editor and click "Modify" and then click on the + Symbol. By this you make new slots available in QtDesigner;
   or when your slot is called on_(senderName)_(signalName) , Qt autowiring will automatically connect the signals, and you don't have to do this in code or desinger.

2. Create a QMenuBar subclass and implement the custom logic there.
   Your case tell Qt Designer to select your specific subclass as replacement for the default QMenuBar by right-clicking on it, and select "Promote to...". In the new dialog, you can specify your custom class that will be used as replacement in actual code, but in design time a QMenuBar is used. With this mehtod, you don't have to write a separate plugin to make your class available in Qt Designer.

Note that with the second option, your custom logic will only be called when the actions are triggered through the menu bar, not by shortcuts or tool buttons

Answer 2

Create a slot in your class:

onMenuActionTriggered()

Use the connect() to react on action's signal:

connect(ui.myAction, SIGNAL(triggered()), this, SLOT(onMenuActionTriggered()));

In your slot you can do whatever you want.

Another solution (not my favourite one, but possible) is to use the auto-connect functionality, which means, by declaring a slot 'on_myAction_triggered()' (where myAction is the name of your QAction) you don't need to use the connect() since it is automatically connected by Qt

Answer 3

The menu bar is automatically added to any new form derived from QMainWindow (the default when creating a gui application, but you can create new main windows using file->new file or project... and selecting Qt->Qt Designer Form Class ).

To add options to it you simply click in the area labeled "Type here" and write your option text. When you do so an action will appear in a list in the lower part of Qt Designer. Right click on that action and select "go to slot". It will pop up a dialog with "triggered()" already selected for you. Simply click "Ok" and Qt Creator will take care of all the details and transport you to the body of the slot function.