Update GUI from another thread

[Lykurg]

You don't have to subclass QThread, you can simply use existing classes for compilation and use them "directly":

#include <QtGui>
 
 
class calc : public QObject
{
    Q_OBJECT
 
  public Q_SLOTS:
    void doCalc()
    {
      for (int i = 1; i < 25; ++i)
      {
        Q_EMIT message(QString::number(i));
        QTime t = QTime::currentTime();
        t = t.addSecs(2);
        while (t > QTime::currentTime()) {}
      }
    }
 
  Q_SIGNALS:
    void message(QString);
};
 
 
int main(int argv, char** args)
{
  QApplication app(argv, args);
 
  // GUI
  QWidget w;
  QPushButton* b = new QPushButton("start", &w);
  QLabel* l = new QLabel(&w);
  QLineEdit* le = new QLineEdit(&w);
  QVBoxLayout* la = new QVBoxLayout();
  la->addWidget(l);
  la->addWidget(b);
  la->addWidget(le);
  w.setLayout(la);
  w.show();
 
  // Thread
  calc c;
  QThread t;
  c.moveToThread(&t);
  t.start();
 
  // Connections
  QObject::connect(&c, SIGNAL(message(QString)), l, SLOT(setText(QString)));
  QObject::connect(b, SIGNAL(clicked()), &c, SLOT(doCalc()));
 
  return app.exec();
}
 
#include "main.moc"

#include <QtGui>


class calc : public QObject
{
    Q_OBJECT

  public Q_SLOTS:
    void doCalc()
    {
      for (int i = 1; i < 25; ++i)
      {
        Q_EMIT message(QString::number(i));
        QTime t = QTime::currentTime();
        t = t.addSecs(2);
        while (t > QTime::currentTime()) {}
      }
    }

  Q_SIGNALS:
    void message(QString);
};


int main(int argv, char** args)
{
  QApplication app(argv, args);

  // GUI
  QWidget w;
  QPushButton* b = new QPushButton("start", &w);
  QLabel* l = new QLabel(&w);
  QLineEdit* le = new QLineEdit(&w);
  QVBoxLayout* la = new QVBoxLayout();
  la->addWidget(l);
  la->addWidget(b);
  la->addWidget(le);
  w.setLayout(la);
  w.show();

  // Thread
  calc c;
  QThread t;
  c.moveToThread(&t);
  t.start();

  // Connections
  QObject::connect(&c, SIGNAL(message(QString)), l, SLOT(setText(QString)));
  QObject::connect(b, SIGNAL(clicked()), &c, SLOT(doCalc()));

  return app.exec();
}

#include "main.moc"

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