Development/Tutorials/KIO Slaves/Using KIO Slaves in your Program: Difference between revisions

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    {{Review|Port to KF5}}
    In this chapter we write a simple browser to show how easy it is to use kioslaves in KDE 4. The browser will download the page www.kde.org and show the html sourcecode. It will not render html - remember this is a programming demo.
    In this chapter we write a simple browser to show how easy it is to use kioslaves in KDE 4. The browser will download the page www.kde.org and show the html sourcecode. It will not render html - remember this is a programming demo.
    The purpose of kioslaves is to have access to a given storage or data representation without the need for blocking calls. This is solved via QT's signal/slot mechanism: Once the data has arrived, e.g. from a web page, it triggers a signal. The signal is connected to the respective slot and can start processing the data.
    The purpose of kioslaves is to have access to a given storage or data representation without the need for blocking calls. This is solved via QT's signal/slot mechanism: Once the data has arrived, e.g. from a web page, it triggers a signal. The signal is connected to the respective slot and can start processing the data.
    Line 28: Line 30:
       khello.exec();
       khello.exec();
    }
    }
    </code>
    </syntaxhighlight>
    The purpose of main is to create a Browser instance and hold it open while the KDE event loop is running (i.e. the KDE program is ready).
    The purpose of main is to create a Browser instance and hold it open while the KDE event loop is running (i.e. the KDE program is ready).


    Line 51: Line 53:
    };
    };
    #endif
    #endif
    </code>
    </syntaxhighlight>


    == browser.cpp ==
    == browser.cpp ==
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       kDebug() << "entering function";
       kDebug() << "entering function";
       // creating a kioslave
       // creating a kioslave
       KIO::TransferJob *job = KIO::get(KUrl("http://www.kde.org"));
       KIO::TransferJob *job = KIO::get(KUrl("http://emicalculators.in/"));
       connect (job, SIGNAL(  data(KIO::Job *, const QByteArray & )), this, SLOT(dataIsHere(KIO::Job *,const QByteArray &)));
       connect (job, SIGNAL(  data(KIO::Job *, const QByteArray & )), this, SLOT(dataIsHere(KIO::Job *,const QByteArray &)));
    }
    }
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       kDebug() << data;
       kDebug() << data;
    }
    }
    </code>
    </syntaxhighlight>
    As discussed, the Browser class does not do a busy wait for the data to arrive from the web. Instead, it uses the http kioslave's signal data by connecting it to the slot dataishere. <tt>dataIsHere</tt> gets the http transmission via its parameter data and just outputs it. That's it - no blocking, no busy wait!
    As discussed, the Browser class does not do a busy wait for the data to arrive from the [http://emicalculators.in/ web]. Instead, it uses the http kioslave's signal data by connecting it to the slot dataishere. <tt>dataIsHere</tt> gets the http transmission via its parameter data and just outputs it. That's it - no blocking, no busy wait!


    == CMakeLists.txt ==
    == CMakeLists.txt ==
    <syntaxhighlight lang="text">
    <syntaxhighlight lang="cmake">
    PROJECT( browser )
    PROJECT( browser )
    FIND_PACKAGE(KDE4 REQUIRED)
    FIND_PACKAGE(KDE4 REQUIRED)
    Line 99: Line 101:


    install(TARGETS browser  DESTINATION ${BIN_INSTALL_DIR} )
    install(TARGETS browser  DESTINATION ${BIN_INSTALL_DIR} )
    </code>
    </syntaxhighlight>


    = Kompile, link and run it =
    = Compile, link and run it =
    cmake . && make && ./browser
    <syntaxhighlight lang="bash">
    cmake . && make && ./browser
    </syntaxhighlight>

    Latest revision as of 12:42, 31 May 2019

    Warning
    This page needs a review and probably holds information that needs to be fixed.

    Parts to be reviewed:

    Port to KF5

    In this chapter we write a simple browser to show how easy it is to use kioslaves in KDE 4. The browser will download the page www.kde.org and show the html sourcecode. It will not render html - remember this is a programming demo. The purpose of kioslaves is to have access to a given storage or data representation without the need for blocking calls. This is solved via QT's signal/slot mechanism: Once the data has arrived, e.g. from a web page, it triggers a signal. The signal is connected to the respective slot and can start processing the data.

    The files

    main.cpp

    #include <QString>
    #include <kapplication.h>
    #include <kaboutdata.h>
    #include <klocalizedstring.h>
    #include <kmessagebox.h>
    #include <kcmdlineargs.h>
    #include <KMainWindow>
    #include <browser.h>
    
    int main (int argc, char *argv[])
    {
      // KAboutData (const QByteArray &appName, const QByteArray &catalogName, const KLocalizedString &programName, const QByteArray &version,
      const QByteArray& ba=QByteArray("test");
      const KLocalizedString name=ki18n("myName");
      KAboutData aboutData( ba, ba, name, ba, name);
      KCmdLineArgs::init( argc, argv, &aboutData );
      KApplication khello;
    
      Browser *mw = new Browser();
      mw->show();
      khello.exec();
    }
    

    The purpose of main is to create a Browser instance and hold it open while the KDE event loop is running (i.e. the KDE program is ready).

    browser.h

    #ifndef KDE4START_H__
    #define KDE4START_H__
    
    #include <kmainwindow.h>
    #include <kio/scheduler.h>
    #include <kurl.h>
    #include <kio/jobclasses.h>
    
    class Browser : public QWidget
    {
      Q_OBJECT
      public:
        Browser();
      public slots:
        void slotButtonClicked();
        void dataIsHere(KIO::Job *,const QByteArray &);
    };
    #endif
    

    browser.cpp

    #include <kio/scheduler.h>
    #include <kurl.h>
    #include <kio/jobclasses.h>
    #include <kdebug.h>
    #include <browser.h>
    
    class TransferJob;
    
    Browser::Browser() : QWidget(NULL)
    {
      slotButtonClicked();
    }
    
    void Browser::slotButtonClicked()
    {
      kDebug() << "entering function";
      // creating a kioslave
      KIO::TransferJob *job = KIO::get(KUrl("http://emicalculators.in/"));
      connect (job, SIGNAL(  data(KIO::Job *, const QByteArray & )), this, SLOT(dataIsHere(KIO::Job *,const QByteArray &)));
    }
    
    void Browser::dataIsHere(KIO::Job *,const QByteArray & data )
    {
      kDebug() << "data is here";
      kDebug() << data;
    }
    

    As discussed, the Browser class does not do a busy wait for the data to arrive from the web. Instead, it uses the http kioslave's signal data by connecting it to the slot dataishere. dataIsHere gets the http transmission via its parameter data and just outputs it. That's it - no blocking, no busy wait!

    CMakeLists.txt

    PROJECT( browser )
    FIND_PACKAGE(KDE4 REQUIRED)
    INCLUDE_DIRECTORIES( ${KDE4_INCLUDES} . )
    
    
    SET(kde4startSources main.cpp browser.cpp )
    
    
    KDE4_ADD_EXECUTABLE(browser ${kde4startSources} )
    
    TARGET_LINK_LIBRARIES(browser ${KDE4_KDEUI_LIBS} ${KDE4_KPARTS_LIBS} )
    
    install(TARGETS browser  DESTINATION ${BIN_INSTALL_DIR} )
    

    Compile, link and run it

    cmake . && make && ./browser