Qt Signal Slot Editor Custom Slot
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To establish a signal and slot connection between two widgets in a dialog, you first need to switch to Qt Designer's Edit Signals/Slots mode. To do that, you can press the F4 key, select the EditEdit Signals/Slots option in the main menu, or click on the Edit Signals/Slots button on the toolbar. Signals, slots, QOBJECT, emit, SIGNAL, SLOT. Those are known as the Qt extension to C. They are in fact simple macros, defined in qobjectdefs.h. #define signals public #define slots /. nothing./ That is right, signals and slots are simple functions: the compiler will handle them them like any other functions.
I was going through the 'Getting started' section for Qt using VS2012 as my IDE, and I got stuck when I had to add a slot to a button. Apparently there is a bug when using the Visual Studio add-in, that the submenu Go to slot doesn't show up in a context menu in Qt Designer (see bug). Needless to say, I spent more than two hours trying to figure out how to get around this problem. The following is what I found:Let's say you have a class called Notepad that has a quit button and you want to handle when the button is clicked
. First create a private slot in the class definition in the header file - Notepad.h in this example. class Notepad : public QMainWindow
{
...
private slots:
public void on_quitButton_clicked();
...
}
On the Notepad.cpp add the following:
void Notepad::on_quitButton_clicked();
{
Qt Signal Slot Editor Custom Slot Machines
}
Note: from what I read it's good idea to follow the convention on_name
Now open your *.ui file with Qt Designer. At this point I tried using the Signal/Slot editor to add the slot to the button on the GUI. The 'custom' slot we wrote above however doesn't show up when you click the slot dropdown.
After scouring stackoverflow and the Qt forums I found a couple of ways to get the custom slot to show in the dropdown.
- Go to Signal/Slots mode by pressing F4 on your keyboard.
- Click on the button so that it changes color.
- Left-click and drag it to the top of the main window.
4. This brings up the Configure Connection window
5. On the left pane select the Signal clicked()
6. On the right pane select Edit
7. This brings yet another window, select the + button.
8. Enter the name of the custom slot, on_quitButton_clicked() in this case.
9. Click Ok and now you should be able to see the slot in the dropdown in Signal/Slot editor.