Qt 4.3: Web Browser Example (ActiveQt)

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# Web Browser Example (ActiveQt)

Files:

- activeqt/webbrowser/webaxwidget.h
- activeqt/webbrowser/main.cpp

The Web Browser example uses the Microsoft Web Browser ActiveX control to implement a fully functional Web Browser application. The user interface has been developed using the Qt Designer integration of the QAxWidget class.

The code demonstrates how the Qt application can communicate with the embedded ActiveX controls using signals, slots and the dynamicCall() function.

     class MainWindow : public QMainWindow, public Ui::MainWindow
     {
         Q_OBJECT
     public:
         MainWindow();

     public slots:
         void on_WebBrowser_TitleChange(const QString &title);
         void on_WebBrowser_ProgressChange(int a, int b);
         void on_WebBrowser_CommandStateChange(int cmd, bool on);
         void on_WebBrowser_BeforeNavigate();
         void on_WebBrowser_NavigateComplete(QString);

         void on_actionGo_triggered();
         void on_actionNewWindow_triggered();
         void on_actionAbout_triggered();
         void on_actionAboutQt_triggered();

     private:
         QProgressBar *pb;
     };

The `MainWindow` class declares a `QMainWindow` based user interface, using the `Ui::MainWindow` class generated by Qt Designer. A number of slots are implemented to handle events from the various user interface elements, including the `WebBrowser` object, which is a QAxWidget hosting the Microsoft Web Browser control.

     MainWindow::MainWindow()
     {
         setupUi(this);

         connect(addressEdit, SIGNAL(returnPressed()), actionGo, SLOT(trigger()));
         connect(actionBack, SIGNAL(triggered()), WebBrowser, SLOT(GoBack()));
         connect(actionForward, SIGNAL(triggered()), WebBrowser, SLOT(GoForward()));
         connect(actionStop, SIGNAL(triggered()), WebBrowser, SLOT(Stop()));
         connect(actionRefresh, SIGNAL(triggered()), WebBrowser, SLOT(Refresh()));
         connect(actionHome, SIGNAL(triggered()), WebBrowser, SLOT(GoHome()));
         connect(actionSearch, SIGNAL(triggered()), WebBrowser, SLOT(GoSearch()));

         pb = new QProgressBar(statusBar());
         pb->setTextVisible(false);
         pb->hide();
         statusBar()->addPermanentWidget(pb);

         WebBrowser->dynamicCall("GoHome()");
     }

The constructor initializes the user interface, installs a progress bar on the status bar, and uses QAxBase::dynamicCall() to invoke the `GoHome()` method of Internet Explorer to navigate to the user's home page.

     void MainWindow::on_WebBrowser_TitleChange(const QString &title)
     {
         setWindowTitle("Qt WebBrowser - " + title);
     }

     void MainWindow::on_WebBrowser_ProgressChange(int a, int b)
     {
         if (a <= 0 || b <= 0) {
             pb->hide();
             return;
         }
         pb->show();
         pb->setRange(0, b);
         pb->setValue(a);
     }

     void MainWindow::on_WebBrowser_CommandStateChange(int cmd, bool on)
     {
         switch (cmd) {
         case 1:
             actionForward->setEnabled(on);
             break;
         case 2:
             actionBack->setEnabled(on);
             break;
         }
     }

     void MainWindow::on_WebBrowser_BeforeNavigate()
     {
         actionStop->setEnabled(true);
     }

     void MainWindow::on_WebBrowser_NavigateComplete(QString)
     {
         actionStop->setEnabled(false);
     }

Different slots handle the signals emitted by the WebBrowser object.

Connections that don't require any coding, i.e. connecting the `back` action to the `GoBack()` slot, have already been made in Qt Designer.

     void MainWindow::on_actionGo_triggered()
     {
         WebBrowser->dynamicCall("Navigate(const QString&)", addressEdit->text());
     }

     void MainWindow::on_actionNewWindow_triggered()
     {
         MainWindow *window = new MainWindow;
         window->show();
         if (addressEdit->text().isEmpty())
             return;
         window->addressEdit->setText(addressEdit->text());
         window->actionStop->setEnabled(true);
         window->on_actionGo_triggered();
     }

     void MainWindow::on_actionAbout_triggered()
     {
         QMessageBox::about(this, tr("About WebBrowser"),
                     tr("This Example has been created using the ActiveQt integration into Qt Designer.\n"
                        "It demonstrates the use of QAxWidget to embed the Internet Explorer ActiveX\n"
                        "control into a Qt application."));
     }

     void MainWindow::on_actionAboutQt_triggered()
     {
         QMessageBox::aboutQt(this, tr("About Qt"));
     }

     #include "main.moc"

     int main(int argc, char ** argv)
     {
         QApplication a(argc, argv);
         MainWindow w;
         w.show();
         return a.exec();
     }

The rest of the implementation is not related to ActiveQt - the actions are handled by different slots, and the entry point function starts the application using standard Qt APIs.

To build the example you must first build the QAxContainer library. Then run your make tool in `examples/activeqt/webbrowser` and run the resulting `webbrowser.exe`.