Development/Tutorials/Programming Tutorial KDE 4/KDirWatch: Difference between revisions

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#endif // _KHELLO_H_
#endif // _KHELLO_H_
</code>
</syntaxhighlight>
This subclasses {{class|KMainWindow}}.
This subclasses {{class|KMainWindow}}.


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#include "khello.moc"
#include "khello.moc"
</code>
</syntaxhighlight>
When instanciated, the class creates a KDirWatcher object and tells it to watch the file passed in by the arguments (<syntaxhighlight lang="text">dw.addFile(args)</code>). The DirWatcher will now emit a SIGNAL dirty each time this file gets modified. This signal is connected to khello's slot ''slotdirty()''. So, every time the file gets modified, slotdirty is called.
When instanciated, the class creates a KDirWatcher object and tells it to watch the file passed in by the arguments (<syntaxhighlight lang="text">dw.addFile(args)</syntaxhighlight>). The DirWatcher will now emit a SIGNAL dirty each time this file gets modified. This signal is connected to khello's slot ''slotdirty()''. So, every time the file gets modified, slotdirty is called.


===main.cpp===
===main.cpp===
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     return app.exec();
     return app.exec();
}
}
</code>
</syntaxhighlight>


==CMake==
==CMake==
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target_link_libraries( dirwatch ${KDE4_KDEUI_LIBS}  
target_link_libraries( dirwatch ${KDE4_KDEUI_LIBS}  
   ${KDE4_KIO_LIBS} )
   ${KDE4_KIO_LIBS} )
</code>
</syntaxhighlight>
Note that we added ''${KDE4_KIO_LIBS}'' to the ''target_link_libraries''. If we do not do it, the linker complains about undefined symbols. In the kio-libs, KDirWatch is defined.
Note that we added ''${KDE4_KIO_LIBS}'' to the ''target_link_libraries''. If we do not do it, the linker complains about undefined symbols. In the kio-libs, KDirWatch is defined.



Latest revision as of 20:54, 29 June 2011

Warning
If this is going to be made into a proper tutorial, it should be on the main tutorial page. Not a part of this small tutorial series.


Using KDirWatch

If you want your program to be notified upon file changes, use KDirWatch. Here is an example.

khello.h

#ifndef _KHELLO_H_
#define _KHELLO_H_

#include <kmainwindow.h>
#include <kdirwatch.h>

/**
 * @short Application Main Window
 * @author Thorsten Staerk <[email protected]>
 * @version 0.1
 */
class khello : public KMainWindow
{
    Q_OBJECT
public:
    KDirWatch dw;
    /**
     * Default Constructor
     */
    khello(char* args);

public slots:
    void slotdirty();

};

#endif // _KHELLO_H_

This subclasses KMainWindow.

khello.cpp

#include "khello.h"

#include <qlabel.h>

#include <kdebug.h>
#include <kmainwindow.h>
#include <klocale.h>
#include <kmessagebox.h>

khello::khello(char* args)
    : KMainWindow()
{
    kdDebug() << "args = " << args << endl;
    dw.addFile(args);
    kdDebug() << "Watching file " << args << endl;
    connect(&dw, SIGNAL(dirty(const QString & ) ),
           SLOT( slotdirty() ) );
}

void khello::slotdirty()
{
  kdDebug() << "File has changed" << endl;
}

#include "khello.moc"

When instanciated, the class creates a KDirWatcher object and tells it to watch the file passed in by the arguments (

dw.addFile(args)

). The DirWatcher will now emit a SIGNAL dirty each time this file gets modified. This signal is connected to khello's slot slotdirty(). So, every time the file gets modified, slotdirty is called.

main.cpp

/*
This program is a demo how to react on file changes.
*/

#include "khello.h"
#include <kapplication.h>
#include <kaboutdata.h>
#include <kcmdlineargs.h>
#include <kdebug.h>
#include <klocale.h>

static const char description[] =
    I18N_NOOP("An ");

static const char version[] = "0.1";

static KCmdLineOptions options[] =
{
    { "+[URL]", I18N_NOOP( "Document to open" ), 0 },
    KCmdLineLastOption
};

int main(int argc, char **argv)
{
    KAboutData about("khello", I18N_NOOP("khello"), version, 
      description, KAboutData::License_GPL, 
      "(C) %{YEAR} Thorsten Staerk", 0, 0, "[email protected]");
    about.addAuthor( "Thorsten Staerk", 0, "[email protected]" );
    KCmdLineArgs::init(argc, argv, &about);
    KCmdLineArgs::addCmdLineOptions( options );
    KApplication app;

    KCmdLineArgs *args = KCmdLineArgs::parsedArgs();
    kdDebug() << argv[1] << endl;
    khello *mainWin = new khello(argv[1]);
    mainWin->show();

    return app.exec();
}

CMake

The best way to build the program is to use CMake.

CMakeLists.txt

project (dirwatch)
find_package(KDE4 REQUIRED KIO KDIRWATCH)
include_directories( ${KDE4_INCLUDES} )
set(dirwatch_SRCS
        main.cpp
        khello.cpp
)
kde4_add_executable(dirwatch ${dirwatch_SRCS})
target_link_libraries( dirwatch ${KDE4_KDEUI_LIBS} 
  ${KDE4_KIO_LIBS} )

Note that we added ${KDE4_KIO_LIBS} to the target_link_libraries. If we do not do it, the linker complains about undefined symbols. In the kio-libs, KDirWatch is defined.

Compile it

To compile, link and run it, use:

cmake . && make && ./dirwatch /var/log/messages

If /var/log/messages changes, the program will notify you about it.