Development/Tutorials/KCmdLineArgs/KDE4

Command line arguments (Under construction User:milliams)

Tutorial Series	Beginner Tutorial
Previous	Tutorial 4 - Loading and saving
What's Next	Tutorial 6 - ### (TODO User:milliams)
Further Reading	KCmdLineArgs KCmdLineOptions

Abstract

Now that we have a text editor which can open and save files. We will now make the editor act more like a desktop application by enabling it to open files from command line arguments or even using Open with from within Dolphin.

The source code on this page applies only to KDE Development Platform 4 ("KDE 4"). For the KDE Frameworks 5 ("KF5") version, see Development/Tutorials/KCmdLineArgs/KF5

The Code

main.cpp

#include <KApplication>
#include <KAboutData>
#include <KCmdLineArgs>
#include <KUrl> //new
 
#include "mainwindow.h"
 
int main (int argc, char *argv[])
{
  KAboutData aboutData( "tutorial5", "tutorial5",
      ki18n("Tutorial 5"), "1.0",
      ki18n("A simple text area which can load and save."),
      KAboutData::License_GPL,
      ki18n("Copyright (c) 2007 Developer") );
  KCmdLineArgs::init( argc, argv, &aboutData );

  KCmdLineOptions options; //new
  options.add("+[file]", ki18n("Document to open")); //new
  KCmdLineArgs::addCmdLineOptions(options); //new

  KApplication app;
 
  MainWindow* window = new MainWindow();
  window->show();

  KCmdLineArgs *args = KCmdLineArgs::parsedArgs(); //new
  if(args->count()) //new
  {
    window->openFile(args->url(0).url()); //new
  }

  return app.exec();
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <KXmlGuiWindow>
#include <KTextEdit>
 
class MainWindow : public KXmlGuiWindow
{
  Q_OBJECT
  
  public:
    MainWindow(QWidget *parent=0);
    void openFile(const QString &inputFileName); //new
  
  private:
    KTextEdit* textArea;
    void setupActions();
    QString fileName;
 
  private slots:
    void newFile();
    void openFile();
    void saveFile();
    void saveFileAs();
    void saveFileAs(const QString &outputFileName);
};
 
#endif

mainwindow.cpp

#include "mainwindow.h"
 
#include <KApplication>
#include <KAction>
#include <KLocale>
#include <KActionCollection>
#include <KStandardAction>
#include <KFileDialog>
#include <KMessageBox>
#include <KIO/NetAccess>
#include <KSaveFile>
#include <QTextStream>
 
MainWindow::MainWindow(QWidget *parent)
    : KXmlGuiWindow(parent),
      fileName(QString())
{
  textArea = new KTextEdit;
  setCentralWidget(textArea);
 
  setupActions();
}
 
void MainWindow::setupActions()
{
  KAction* clearAction = new KAction(this);
  clearAction->setText(i18n("Clear"));
  clearAction->setIcon(KIcon("document-new"));
  clearAction->setShortcut(Qt::CTRL + Qt::Key_W);
  actionCollection()->addAction("clear", clearAction);
  connect(clearAction, SIGNAL(triggered(bool)),
          textArea, SLOT(clear()));
 
  KStandardAction::quit(kapp, SLOT(quit()),
                        actionCollection());
 
  KStandardAction::open(this, SLOT(openFile()),
                        actionCollection());
 
  KStandardAction::save(this, SLOT(saveFile()),
                        actionCollection());
 
  KStandardAction::saveAs(this, SLOT(saveFileAs()),
                        actionCollection());
 
  KStandardAction::openNew(this, SLOT(newFile()),
                        actionCollection());
 
  setupGUI();
}
 
void MainWindow::newFile()
{
  fileName.clear();
  textArea->clear();
}
 
void MainWindow::saveFileAs(const QString &outputFileName)
{
  KSaveFile file(outputFileName);
  file.open();
  
  QByteArray outputByteArray;
  outputByteArray.append(textArea->toPlainText());
  file.write(outputByteArray);
  file.finalize();
  file.close();
  
  fileName = outputFileName;
}
 
void MainWindow::saveFileAs()
{
  saveFileAs(KFileDialog::getSaveFileName());
}
 
void MainWindow::saveFile()
{
  if(!fileName.isEmpty())
  {
    saveFileAs(fileName);
  }
  else
  {
    saveFileAs();
  }
}
 
void MainWindow::openFile() //changed
{
  openFile(KFileDialog::getOpenFileName());
}

void MainWindow::openFile(const QString &inputFileName) //new
{
  QString tmpFile;
  if(KIO::NetAccess::download(inputFileName, tmpFile, 
         this))
  {
    QFile file(tmpFile);
    file.open(QIODevice::ReadOnly);
    textArea->setPlainText(QTextStream(&file).readAll());
    fileName = inputFileName;
 
    KIO::NetAccess::removeTempFile(tmpFile);
  }
  else
  {
    KMessageBox::error(this, 
        KIO::NetAccess::lastErrorString());
  }
}

tutorial5ui.rc

<?xml version="1.0" encoding="UTF-8"?>
<gui name="tutorial5"
     version="1"
     xmlns="http://www.kde.org/standards/kxmlgui/1.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://www.kde.org/standards/kxmlgui/1.0
                         http://www.kde.org/standards/kxmlgui/1.0/kxmlgui.xsd" >

  <MenuBar>
    <Menu name="file" >
      <Action name="clear" />
    </Menu>
  </MenuBar>

  <ToolBar name="mainToolBar" >
    <text>Main Toolbar</text>
    <Action name="clear" />
  </ToolBar>

</gui>

This is identical to the tutorialxui.rc from the last two tutorials except tutorialx is now tutorial5.

Explanation

mainwindow.h

Here we have done nothing but add a new openFile function which takes a QString

void openFile(const QString &inputFileName);

mainwindow.cpp

There's no new code here, only rearranging. Everything from void openFile() has been moved into void openFile(const QString &inputFileName) except the call to KFileDialog::getOpenFileName().

This way, we can call openFile() if we want to display a dialog, or we can call openFile(QString) if we know the name of the file already.

main.cpp

This is where all the KCmdLineArgs magic happens.

Make, Install And Run

CMakeLists.txt

project(tutorial5)
 
find_package(KDE4 REQUIRED)
include_directories( ${KDE4_INCLUDES} )
 
set(tutorial5_SRCS 
  main.cpp
  mainwindow.cpp
)
 
kde4_add_executable(tutorial5 ${tutorial5_SRCS})
 
target_link_libraries(tutorial5 ${KDE4_KDEUI_LIBS}
                                ${KDE4_KIO_LIBS})
 
install(TARGETS tutorial5 DESTINATION ${BIN_INSTALL_DIR})
install( FILES tutorial5ui.rc 
         DESTINATION  ${DATA_INSTALL_DIR}/tutorial5 )

With this file, the tutorial can built and run in the same way as tutorial 3 and 4. For more information, see tutorial 3.

mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME
make install
$HOME/bin/tutorial5

Moving On

Now you can move on to the ### (TODO User:milliams) tutorial.