Development/Tutorials/KCmdLineArgs

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 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.