[FIXED] Embeding PySide/PyQt widget into Qt/C++ application

Issue

I have a C++/Qt application which should have its GUI extensible with modules. Extending should be simple and versatile. I am just checking a concept - is it possible to have this main C++/Qt application that would execute a Python/PySide/PyQt script which would create a QWidget (or derived class) instance and embed this widget into the main C++/Qt application?

Is there any working snippet to demonstrate the feasibility of this task? I.e. how to create and embed the widget? How to pass signals between the application and the widget?

Solution

This question is a bit old, but in case someone else is face the same issue, I will try to give a useful answer.

I think it's possible. In the following example, I create a QApplication and QMainWindow in c++, embed a python interpreter, and then, on the python side, I create a QPushButton which I add to the main window.

Try this out:

#include <QApplication>
#include <QMainWindow>

#include <iostream>
#include "Python.h"

class PythonQt
{

public:

  PythonQt()
  {
    char name[] = "test";
    Py_SetProgramName(name);
    Py_Initialize();

    std::string code =
        "from PySide import QtGui\n"
        ""
        "all_widgets = QtGui.QApplication.instance().allWidgets()\n"
        "window = None\n"
        "for widget in all_widgets:\n"
        "    if str(widget.objectName()) == \"main_window\":\n"
        "      window = widget\n"
        "      break\n"
        ""
        "def message_box():\n"
        "    QtGui.QMessageBox.information(None, 'Test', 'Hello!', \ 
                      QtGui.QMessageBox.Ok)\n"
        "    QtGui.QApplication.instance().quit()\n"
        ""
        "button = QtGui.QPushButton('Press Me')\n"
        "button.clicked.connect(message_box)\n"
        "window.setCentralWidget(button)\n"
        "window.move(600, 300)\n"
        "window.show()";

    PyRun_SimpleString(code.c_str());
  }

};

int main(int argc, char *argv[])
{
  QApplication a(argc, argv);
  QMainWindow win;
  win.setObjectName("main_window");

  PythonQt python_code;

  a.exec();
}

The python script is written here in a string to have everything in a single file, but you could of course read it in from a .py file.

Object ownership could be an issue though, as shown in the link given by Trilarion.

Answered By - Francois