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

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{{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==
==Using KDirWatch==


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


===mainwindow.h===
===khello.h===
<code cppqt>
<syntaxhighlight lang="cpp-qt">
#ifndef MAINWINDOW_H
#ifndef _KHELLO_H_
#define MAINWINDOW_H
#define _KHELLO_H_


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


class MainWindow : public KXmlGuiWindow
/**
* @short Application Main Window
* @author Thorsten Staerk <[email protected]>
* @version 0.1
*/
class khello : public KMainWindow
{
{
  public:
    Q_OBJECT
     MainWindow(QWidget *parent=0);
public:
     KDirWatch dw;
  private:
    /**
     KTextEdit* textArea;
    * Default Constructor
    */
    khello(char* args);
 
public slots:
     void slotdirty();
 
};
};


#endif
#endif // _KHELLO_H_
</code>
</syntaxhighlight>
First we Subclass KXmlGuiWindow on line 7 with with <tt>class MainWindow : public KXmlGuiWindow</tt>.
This subclasses {{class|KMainWindow}}.


Then we declare the constructor with <tt>MainWindow(QWidget *parent=0);</tt>.
===khello.cpp===
<syntaxhighlight lang="cpp-qt">
#include "khello.h"


And finally we declare a pointer to the object that will make up the bulk of our program. {{class|KTextEdit}} is a generic richtext editor with some KDE niceties like cursor auto-hiding.
#include <qlabel.h>


===mainwindow.cpp===
#include <kdebug.h>
<code cppqt>
#include <kmainwindow.h>
#include "mainwindow.h"
#include <klocale.h>
#include <kmessagebox.h>


MainWindow::MainWindow(QWidget *parent) : KXmlGuiWindow(parent)
khello::khello(char* args)
    : KMainWindow()
{
{
  textArea = new KTextEdit;
    kdDebug() << "args = " << args << endl;
  setCentralWidget(textArea);
    dw.addFile(args);
  setupGUI();
    kdDebug() << "Watching file " << args << endl;
    connect(&dw, SIGNAL(dirty(const QString & ) ),
          SLOT( slotdirty() ) );
}
}
</code>
First, of course, on line 1 we have to include the header file containing the class declaration.


On line 5, we initialise our text editor with an object. Then on line 6 we use the built-in setCentralWidget() function which tells the KXmlGuiWindow what should appear in the central section of the window.
void khello::slotdirty()
{
  kdDebug() << "File has changed" << endl;
}


Finally, KXmlGuiWindow::setupGUI() is called which does a lot of behind-the-scenes stuff and creates the default menu bars (Settings, Help).
#include "khello.moc"
</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)</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.


==Back to main.cpp==
In order to actually run this window, we need to add a few lines in main.cpp:
===main.cpp===
===main.cpp===
<code cppqt>
<syntaxhighlight lang="cpp-qt">
#include <KApplication>
/*
#include <KAboutData>
This program is a demo how to react on file changes.
#include <KCmdLineArgs>
*/
 
#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 ");


#include "mainwindow.h"
static const char version[] = "0.1";
 
static KCmdLineOptions options[] =
{
    { "+[URL]", I18N_NOOP( "Document to open" ), 0 },
    KCmdLineLastOption
};


int main (int argc, char *argv[])
int main(int argc, char **argv)
{
{
  KAboutData aboutData( "tutorial2",  
    KAboutData about("khello", I18N_NOOP("khello"), version,  
      "Tutorial2", "1.0", "A simple text area",
       description, KAboutData::License_GPL,  
       KAboutData::License_GPL, "(c) 2006" );
      "(C) %{YEAR} Thorsten Staerk", 0, 0, "[email protected]");
  KCmdLineArgs::init( argc, argv, &aboutData );
    about.addAuthor( "Thorsten Staerk", 0, "[email protected]" );
 
    KCmdLineArgs::init(argc, argv, &about);
  KApplication app;
    KCmdLineArgs::addCmdLineOptions( options );
    KApplication app;
  MainWindow* window = new MainWindow();
  window->show();


  return app.exec();
    KCmdLineArgs *args = KCmdLineArgs::parsedArgs();
    kdDebug() << argv[1] << endl;
    khello *mainWin = new khello(argv[1]);
    mainWin->show();
 
    return app.exec();
}
}
</code>
</syntaxhighlight>
The only new lines here (compared to Tutorial 1) are 16 and 17. On line 16, we create our MainWindow object and then on line 17, we display it.


==CMake==
==CMake==
The best way to build the program is to use CMake. All that's changed since tutorial 1 is that <tt>mainwindow.cpp</tt> has been added to the sources list and any <tt>tutorial1</tt> has become <tt>tutorial2</tt>.
The best way to build the program is to use CMake.
===CMakeLists.txt===
===CMakeLists.txt===
<code ini>
<syntaxhighlight lang="ini">
project (tutorial2)
project (dirwatch)
find_package(KDE4 REQUIRED)
find_package(KDE4 REQUIRED KIO KDIRWATCH)
include_directories( ${KDE4_INCLUDES} )
include_directories( ${KDE4_INCLUDES} )
set(tutorial2_SRCS
set(dirwatch_SRCS
main.cpp
        main.cpp
mainwindow.cpp
        khello.cpp
)
)
kde4_add_executable(tutorial2 ${tutorial2_SRCS})
kde4_add_executable(dirwatch ${dirwatch_SRCS})
target_link_libraries( tutorial2 ${KDE4_KDEUI_LIBS} ${KDE4_KIO_LIBS} )
target_link_libraries( dirwatch ${KDE4_KDEUI_LIBS}  
</code>
  ${KDE4_KIO_LIBS} )
</syntaxhighlight>
Note that we added ''${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.


===Kompile it===
===Compile it===
To compile, link and run it, use:
To compile, link and run it, use:
  cmake . && make && ./tutorial2
  cmake . && make && ./dirwatch /var/log/messages
 
If {{path|/var/log/messages}} changes, the program will notify you about it.
==Moving On==
Now you can move on to [[Development/Tutorials/Programming_Tutorial_KDE_4/Using_KActions|using KActions]].


[[Category:C++]]
[[Category:C++]]

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.

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