QT Signal and Slot between windows - qt

Question

I want to connect to windows in QT.
I know how to connect two widgets in same window.
using QObject::connect() in ui_a.h;
But now, I have two windows.
Six files.
For example:
ui_a.h(Window A)
a.h a.cpp (Widget in window A)
ui_b.h(Window B)
b.h b.cpp (Widget in window B)
How to connect two widget which are in different windows?
Thank you.

Answer 1

You have to find the scope of both window object and connect them there. Perhaps connecting them from main.cpp would make it easier. For example,
QApplication a(argc, argv);
A a;
B b;
QObject::connect(&a, SIGNAL(someSingal()), &b, SLOT(someSlot()));
QObject::connect(&b, SIGNAL(anotherSingal()), &a, SLOT(anotherSlot()));
a.show();
b.show();
return a.exec();

Answer 2

Do the two windows know about each other or are they completly independent? I mean is maybe Window A created by Window B or vice versa? But even if they are independent I assume you have a top parent-object wich creates the two windows right? If so, you should get access to the two widgets in this top parent object. There you can connect them:
QObject::connect(A->getWidgetInA(), SIGNAL(mySignal()), B->getWidgetInB(), SLOT(mySlot()));
getWidgetInA(), getWidgetInB() just return the pointer to your widgets in Window A and B.
For example in your class Window A: This is how getWidgetInA() would look like.
#include "a.h"
class WindowA: public QMainWindow
{
Q_OBJECT
public:
WindowA();
~WindowA();
a* getWidgetInA()
{
return widget_a;
}
private:
a *widget_a; //in WindowA.cpp you have then widget_a = new a;
}