Development/Tutorials/CommandLineArguments: Difference between revisions

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This tutorial was moved here: https://develop.kde.org/docs/getting-started/commandline/
 
{{TutorialBrowser|
 
series=Beginner Tutorial|
 
name=Command line arguments|
 
pre=[[Development/Tutorials/Saving and loading|Tutorial 4 - Loading and saving]]|
 
}}
 
 
==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.
 
[[image:tutorial5-kf5.png|frame|center]]
 
== The Code ==
 
===main.cpp===
<syntaxhighlight lang="cpp-qt">
#include <cstdlib>
#include <QApplication>
#include <QCommandLineParser>
#include <QUrl>
#include <QDir>
 
#include <KAboutData>
#include <KLocalizedString>
 
#include "mainwindow.h"
int main (int argc, char *argv[])
{
    QApplication app(argc, argv);
   
    KLocalizedString::setApplicationDomain("tutorial5");
   
    KAboutData aboutData(
                        // The program name used internally. (componentName)
                        QStringLiteral("tutorial5"),
                        // A displayable program name string. (displayName)
                        i18n("Tutorial 5"),
                        // The program version string. (version)
                        QStringLiteral("1.0"),
                        // Short description of what the app does. (shortDescription)
                        i18n("A simple text area which can load and save."),
                        // The license this code is released under
                        KAboutLicense::GPL,
                        // Copyright Statement (copyrightStatement = QString())
                        i18n("(c) 2015"),
                        // Optional text shown in the About box.
                        // Can contain any information desired. (otherText)
                        i18n("Some text..."),
                        // The program homepage string. (homePageAddress = QString())
                        QStringLiteral("http://example.com/"),
                        // The bug report email address
                        // (bugsEmailAddress = QLatin1String("[email protected]")
                        QStringLiteral("[email protected]"));
   
    aboutData.addAuthor(i18n("Name"), i18n("Task"), QStringLiteral("[email protected]"),
                        QStringLiteral("http://your.website.com"), QStringLiteral("OSC Username"));
   
    KAboutData::setApplicationData(aboutData);
    QCommandLineParser parser;
    aboutData.setupCommandLine(&parser);
    parser.addPositionalArgument(QStringLiteral("file"), i18n("Document to open"));
   
    parser.process(app);
    aboutData.processCommandLine(&parser);
   
    MainWindow* window = new MainWindow();
    window->show();
   
    if (parser.positionalArguments().count() > 0)
    {
        window->openFile(QUrl::fromUserInput(parser.positionalArguments().at(0), QDir::currentPath()));
    }
   
    return app.exec();
}
</syntaxhighlight>
 
===mainwindow.h===
<syntaxhighlight lang="cpp-qt">
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <KXmlGuiWindow>
 
class KTextEdit;
class KJob;
class MainWindow : public KXmlGuiWindow
{
    Q_OBJECT
   
  public:
    explicit MainWindow(QWidget *parent = nullptr);
    void openFile(const QUrl &inputFileName);
  private:
    void setupActions();
  private slots:
    void newFile();
    void openFile();
    void saveFile();
    void saveFileAs();
    void saveFileAs(const QString &outputFileName);
   
    void downloadFinished(KJob* job);
 
  private:
    KTextEdit* textArea;
    QString fileName;
};
#endif
</syntaxhighlight>
 
===mainwindow.cpp===
<syntaxhighlight lang="cpp-qt">
#include <QApplication>
#include <QAction>
#include <QSaveFile>
#include <QFileDialog>
#include <QTextStream>
#include <QByteArray>
 
#include <KTextEdit>
#include <KLocalizedString>
#include <KActionCollection>
#include <KStandardAction>
#include <KMessageBox>
#include <KIO/Job>
 
#include "mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) : KXmlGuiWindow(parent), fileName(QString())
{
  textArea = new KTextEdit();
  setCentralWidget(textArea);
 
  setupActions();
}
 
void MainWindow::setupActions()
{
    QAction* clearAction = new QAction(this);
    clearAction->setText(i18n("&Clear"));
    clearAction->setIcon(QIcon::fromTheme("document-new"));
    actionCollection()->setDefaultShortcut(clearAction, Qt::CTRL + Qt::Key_W);
    actionCollection()->addAction("clear", clearAction);
    connect(clearAction, SIGNAL(triggered(bool)), textArea, SLOT(clear()));
   
    KStandardAction::quit(qApp, 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(Default, "tutorial5ui.rc");
}
 
void MainWindow::newFile()
{
    fileName.clear();
    textArea->clear();
}
 
void MainWindow::saveFileAs(const QString &outputFileName)
{
    if (!outputFileName.isNull())
    {
        QSaveFile file(outputFileName);
        file.open(QIODevice::WriteOnly);
       
        QByteArray outputByteArray;
        outputByteArray.append(textArea->toPlainText().toUtf8());
        file.write(outputByteArray);
        file.commit();
 
        fileName = outputFileName;
    }
}
 
void MainWindow::saveFileAs()
{
    saveFileAs(QFileDialog::getSaveFileName(this, i18n("Save File As")));
}
 
void MainWindow::saveFile()
{
    if (!fileName.isEmpty())
    {
        saveFileAs(fileName);
    }
    else
    {
        saveFileAs();
    }
}
 
 
void MainWindow::openFile()
{
    openFile(QFileDialog::getOpenFileUrl(this, i18n("Open File")));
}
   
void MainWindow::openFile(const QUrl &inputFileName)
{
    if (!inputFileName.isEmpty())
    {
        KIO::Job* job = KIO::storedGet(inputFileName);
        fileName = inputFileName.toLocalFile();
 
        connect(job, SIGNAL(result(KJob*)), this, SLOT(downloadFinished(KJob*)));
       
        job->exec();
    }
}
 
void MainWindow::downloadFinished(KJob* job)
{
    if (job->error())
    {
        KMessageBox::error(this, job->errorString());
        fileName.clear();
        return;
    }
   
    KIO::StoredTransferJob* storedJob = (KIO::StoredTransferJob*)job;
    textArea->setPlainText(QTextStream(storedJob->data(), QIODevice::ReadOnly).readAll());
}
</syntaxhighlight>
 
===tutorial5ui.rc===
<syntaxhighlight lang="xml">
<?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>
</syntaxhighlight>
 
==Explanation==
 
===mainwindow.h===
 
Here we have done nothing but add a new <tt>openFile</tt> function which takes a <tt>QUrl</tt>. Again, we use a QUrl instead of a QString so that we can also work with remote files as if they were local.
<syntaxhighlight lang="cpp-qt">
void openFile(const QUrl &inputFileName);
</syntaxhighlight>
 
===mainwindow.cpp===
 
There's no new code here, only rearranging. Everything from <tt>void openFile()</tt> has been moved into <tt>void openFile(const QUrl &inputFileName)</tt> except the call to <tt>QFileDialog::getOpenFileUrl()</tt>.
 
This way, we can call <tt>openFile()</tt> if we want to display a dialog, or we can call <tt>openFile(QUrl)</tt> if we know the name of the file already. Which will be the case when we feed the file name through the command line.
 
===main.cpp===
 
This is where all the [http://doc.qt.io/qt-5/qcommandlineparser.html QCommandLineParser] magic happens. In previous examples, we only used the class to feed QApplication the necessary data for using flags like <tt>--version</tt> or <tt>--author</tt>. Now we actually get to use it to process command line arguments.
 
First, we tell QCommandLineParser that we want to add a new positional arguments. In a nutshell, these are arguments that are not options. <tt>-h</tt> or <tt>--version</tt> are options, <tt>file</tt> is an argument.
<syntaxhighlight lang="cpp-qt">
parser.addPositionalArgument(QStringLiteral("file"), i18n("Document to open"));
</syntaxhighlight>
 
 
Later on, we start processing positional arguments, but only if there is one. Otherwise, we proceed as usual. In our case we can only open one file at a time, so only the first file is of interest to us. We call the <tt>openFile()</tt> function and feed it the URL of the file we want to open, whether it is a local file like {{path|$HOME/foo}} or a remote one like {{path|ftp.mydomain.com/bar}}. We use the overloaded form of <tt>[http://doc.qt.io/qt-5/qurl.html#fromUserInput-1 QUrl::fromUserInput()]</tt> in order to set the current path. This is needed in order to work with relative paths like <tt>"../baz"</tt>.
<syntaxhighlight lang="cpp-qt">
if (parser.positionalArguments().count() > 0)
{
    window->openFile(QUrl::fromUserInput(parser.positionalArguments().at(0), QDir::currentPath()));
}
</syntaxhighlight>
 
==Make, Install and Run==
 
===CMakeLists.txt===
<syntaxhighlight lang="cmake">
cmake_minimum_required(VERSION 3.0)
 
project (tutorial5)
 
set(QT_MIN_VERSION "5.3.0")
set(KF5_MIN_VERSION "5.2.0")
 
find_package(ECM 1.0.0 REQUIRED NO_MODULE)
set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 
include(KDEInstallDirs)
include(KDECMakeSettings)
include(KDECompilerSettings NO_POLICY_SCOPE)
include(FeatureSummary)
 
find_package(Qt5 ${QT_MIN_VERSION} CONFIG REQUIRED COMPONENTS
    Core    # QCommandLineParser, QStringLiteral, QSaveFile, QTextStream, QByteArray
    Widgets # QApplication, QAction, QFileDialog
)
 
find_package(KF5 ${KF5_MIN_VERSION} REQUIRED COMPONENTS
    CoreAddons      # KAboutData
    I18n            # KLocalizedString
    XmlGui          # KXmlGuiWindow, KActionCollection
    TextWidgets    # KTextEdit
    ConfigWidgets  # KStandardActions
    WidgetsAddons  # KMessageBox
    KIO            # KIO
)
   
feature_summary(WHAT ALL INCLUDE_QUIET_PACKAGES FATAL_ON_MISSING_REQUIRED_PACKAGES)
   
set(tutorial5_SRCS main.cpp mainwindow.cpp)
 
add_executable(tutorial5 ${tutorial5_SRCS})
 
target_link_libraries(tutorial5
    Qt5::Widgets
    KF5::CoreAddons
    KF5::I18n
    KF5::XmlGui
    KF5::TextWidgets
    KF5::ConfigWidgets
    KF5::WidgetsAddons
    KF5::KIOCore
)
 
install(TARGETS tutorial5  ${KDE_INSTALL_TARGETS_DEFAULT_ARGS})
 
install(FILES tutorial5ui.rc DESTINATION ${KDE_INSTALL_KXMLGUI5DIR}/tutorial5)
</syntaxhighlight>
 
 
With this file, the tutorial can built and run in the same way as tutorial 3 and 4. For more information, see tutorial 3.
<syntaxhighlight lang="bash">
mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME
make install
XDG_DATA_DIRS=$HOME/share:$XDG_DATA_DIRS $HOME/bin/tutorial5
</syntaxhighlight>
 
==Moving On==
 
[[Category:C++]]

Latest revision as of 09:26, 4 October 2020

This tutorial was moved here: https://develop.kde.org/docs/getting-started/commandline/

Retrieved from "https://techbase.kde.org/index.php?title=Development/Tutorials/CommandLineArguments&oldid=106724"