Development/Tutorials/Saving and loading

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Contents

Development/Tutorials/Saving_and_loading


Loading and saving files
Tutorial Series   Beginner Tutorial
Previous   Tutorial 3 - KActions
What's Next   TODO (milliams)
Further Reading   KIO::NetAccess QFile

Abstract

Introtokdetutorial4.png

The Code

main.cpp

  1. include <KApplication>
  2. include <KAboutData>
  3. include <KCmdLineArgs>
  1. include "mainwindow.h"

int main (int argc, char *argv[]) {

 KAboutData aboutData( "tutorial4", "tutorial4",
     ki18n("Tutorial 4"), "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 );
 KApplication app;

 MainWindow* window = new MainWindow();
 window->show();
 return app.exec();

} main.cpp hasn't changed from tutoral 3 except to change any reference to tutorial 3 to tutorial 4.

mainwindow.h

  1. ifndef MAINWINDOW_H
  2. define MAINWINDOW_H
  1. include <KXmlGuiWindow>
  2. include <KTextEdit>

class MainWindow : public KXmlGuiWindow {

 Q_OBJECT //new
 
 public:
   MainWindow(QWidget *parent=0);
 
 private:
   KTextEdit* textArea;
   void setupActions();
   QString fileName; //new
 private slots: //new
   void newFile(); //new
   void openFile(); //new
   void saveFile(); //new
   void saveFileAs(); //new
   void saveFileAs(const QString &outputFileName); //new

};

  1. endif

mainwindow.cpp

  1. include "mainwindow.h"
  1. include <KApplication>
  2. include <KAction>
  3. include <KLocale>
  4. include <KActionCollection>
  5. include <KStandardAction>
  6. include <KFileDialog> //new
  7. include <KMessageBox> //new
  8. include <KIO/NetAccess> //new
  9. include <KSaveFile> //new
  10. include <QTextStream>

MainWindow::MainWindow(QWidget *parent)

   : KXmlGuiWindow(parent),
     fileName(QString()) //new

{

 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()); //new

 KStandardAction::save(this, SLOT(saveFile()),
                       actionCollection()); //new

 KStandardAction::saveAs(this, SLOT(saveFileAs()),
                       actionCollection()); //new

 KStandardAction::openNew(this, SLOT(newFile()),
                       actionCollection()); //new

 setupGUI();

}

void MainWindow::newFile() {

 fileName.clear();
 textArea->clear();

}

void MainWindow::openFile() //new {

 QString fileNameFromDialog = KFileDialog::getOpenFileName();
 QString tmpFile;
 if(KIO::NetAccess::download(fileNameFromDialog, tmpFile, 
        this))
 {
   QFile file(tmpFile);
   file.open(QIODevice::ReadOnly);
   textArea->setPlainText(QTextStream(&file).readAll());
   fileName = fileNameFromDialog;
   KIO::NetAccess::removeTempFile( tmpFile );
 }
 else
 {
   KMessageBox::error(this, 
       KIO::NetAccess::lastErrorString());
 }

}

void MainWindow::saveFile() {

 if(!fileName.isEmpty())
 {
   saveFileAs(fileName);
 }
 else
 {
   saveFileAs();
 }

}

void MainWindow::saveFileAs() {

 saveFileAs(KFileDialog::getSaveFileName());

}

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;

}

tutorial4ui.rc

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE kpartgui SYSTEM "kpartgui.dtd"> <gui name="tutorial4" version="1">

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

</gui> This is identical to tutorial3ui.rc from tutorial 3 except the name has changed to 'tutorial4'. We do not need to add any information about any of the KStandardActions since the placement of those actions is handled automatically by KDE.

Explanation

Make, Install And Run

CMakeLists.txt

project(tutorial4)

find_package(KDE4 REQUIRED) include_directories(${KDE4_INCLUDES})

set(tutorial4_SRCS

 main.cpp
 mainwindow.cpp

)

kde4_add_executable(tutorial4 ${tutorial4_SRCS})

target_link_libraries(tutorial4 ${KDE4_KDEUI_LIBS} ${KDE4_KIO_LIBS})

install(TARGETS tutorial4 DESTINATION ${BIN_INSTALL_DIR}) install(FILES tutorial4ui.rc

       DESTINATION ${DATA_INSTALL_DIR}/tutorial4)

Since we are now using the KIO library, we must tell CMake to link against it. We do this by passing ${KDE4_KIO_LIBS} to the target_link_libraries() function.

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

mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME
make install
$HOME/bin/tutorial4

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