Development/Tutorials/Using KActions (de)

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Development/Tutorials/Using_KActions


Zusammenfassung

In diesem Kapitel wird das Konzept der Aktionen eingeführt. Aktionen sind ein vereinheitlichter Weg, dem Benutzer eine Interaktion mit Ihrem Programm zu ermöglichen

Soll zum Beispiel durch das Klicken eines Buttons, einem Eintrag im Dateimenü oder einem Tastaturshortcut das Textfeld geleert werden, wird dies alles durch eine KAction bewerkstelligt.

KAction

Eine KAction ist ein Objekt, welches alle Informationen über das Icon und Shortcuts enthält, welche mit einer bestimmten Aktion assoziiert sind. Diese Aktion läßt sich mit einemslot verbinden, welcher dann bestimmte Arbeiten ausführt, die bei dieser Aktion vorgesehen sind.

Eine eigene Aktion erzeugen

Um eine Aktion zu erzeugen, muss #include <KAction> in die .cpp Datei eingefügt werden.

Das Objekt erzeugen

Wir werden hier eine Aktion erzeugen, welche die Applikation aus Kapitel 2 dahingehend erweitert, dass durch sie das Textfeld geleert wird. Die KAction wird in einer Reihe einzelner Schritte zusammengestellt. Zunächst wird das Objekt selber erzeugt: KAction* clearAction = new KAction(this); Das erzeugt ein KAction-Objekt welches clearAction heißt.

Text

Bei dem jetzt erzeugten KAction Objekt können jetzt die Eigenschaften gesetzt werden. Zunächst setzen wir einen Text der im Menü und unter seinem Icon in der Werkzeugleiste angezeigt wird: clearAction->setText(i18n("Clear")); Wie man sieht, muss dieser Text durch die i18n() Funktion geleitet werden, wenn man das Benutzerinterface später übersetzen möchte.

Icon

Soll in der Werkzeugleiste die Aktion angezeigt werden, muss man ein Icon verknüpfen, welches die Aktion bildlich beschreibt. Um das zu bewekstelligen, benutzen wir die setIcon() Funktion: clearAction->setIcon(KIcon("document-new")); Hier wird das Standardicon document-new von KDE benutzt.

Shortcut

Wir können auch einen Tastaturshortcut definieren, welcher die Aktion ausführt.. Das wird ganz einfach durch clearAction->setShortcut(Qt::CTRL+Qt::Key_W); bewekstelligt. In diesem Fall wird Ctrl+W mit der Aktion verknüpft.

Adding to the Collection

In order for our action to be accessable by the XmlGui framework it must be added to the application's action collection. It is accessed via the actionCollection() function thus: actionCollection()->addAction("clear", clearAction); Here we add the clearAction KAction to the collection and give it a name of clear. This name is used by the XmlGui framework.

Connecting the action

Now our action is fully set up, we need to connect it to something useful. We're going to connect our action to the clear() action belonging to a KTextArea. connect( clearAction, SIGNAL( triggered(bool) ), 

        textArea, SLOT( clear() ) );

This is the same as it would be done in Qt with a QAction.

KStandardAction

For actions which would likely appear in almost every KDE application such as 'quit', 'save', and 'load' there are pre-created convenience KActions, accessed through KStandardAction.

They are very simple to use. Once you've done #include <KStandardAction>, you simply need to supply it with what you want the function to do and which KActionCollection to add it to. For example, KStandardAction::quit(kapp, SLOT(quit()), actionCollection()); Will Create a KAction with the correct icon, text and shortcut and will even add it to the File menu.

The Code

mainwindow.h

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

class MainWindow : public KXmlGuiWindow { 

 public:
   MainWindow(QWidget *parent=0);

 private:
   KTextEdit* textArea;
   void setupActions();

};

  1. endif

mainwindow.cpp

  1. include "mainwindow.h"
  1. include <KApplication>
  2. include <KAction>
  3. include <KLocale>
  4. include <KActionCollection>
  5. include <KStandardAction>

MainWindow::MainWindow(QWidget *parent) 

   : KXmlGuiWindow(parent)

{ 

 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());

 setupGUI();

}

main.cpp

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

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

 KAboutData aboutData( "tutorial3", "tutorial3",
     ki18n("Tutorial 3"), "1.0",
     ki18n("A simple text area using KAction etc."),
     KAboutData::License_GPL,
     ki18n("Copyright (c) 2007 Developer") );
 KCmdLineArgs::init( argc, argv, &aboutData );
 KApplication app;

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

}

Putting the actions in the menus and toolbars

Now, at the moment, we've only created our new "Clear" action. It won't yet show up in the menus or in the toolbars. To tell the program where to put our actions (and to allow the end-user to move them around) we use a KDE technology called XmlGui.

XmlGui

Note
In a later version of KDE4, XmlGui may be replaced with a new framework called liveui. For now, XmlGui is the only and correct way to set up the UI.


When you call setupGUI() in your KXmlGuiWindow class, it calls the XmlGui system which reads an XML file description of your interface (which we will create in a minute) and creates the buttons and menus appropriately.

Now obviously XmlGui needs to know which file is your description file, i.e. it needs to know its name and location. The rule for the naming is the file should be called appnameui.rc (where appname is the name you set in KAboutData), so in our example, the file will be called tutorial3ui.rc. Where the file will be located is handled by CMake.

Writing your appnameui.rc File

Since the description of our UI is being defined with XML, the layout of the description must follow strict rules. We won't go through all the rules in this tutorial but for more information, see the _detailed_XmlGui_page_ (once we have a full explanation of XmlGui (or possibly liveui if that's done soon :)) on the wiki, I'll link it up).

tutorial3ui.rc

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE kpartgui SYSTEM "kpartgui.dtd"> <gui name="tutorial3" version="1"> 

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

</gui>

The <Toolbar> tag allows you to describe the toolbar. That is the bar across the top of the window with the icons. Here we give it a unique name mainToolBar, set it's user visible name Main Toolbar using the <text> tag and finally add our clear action to the toolbar using the <Action> tag. The name parameter in this tag relates to the string that was passed to the addAction() function in the C++ code.

As well as having our action in the toolbar, we can also add it to the menubar. Within the <MenuBar> tag, we say we want to add our action to the File menu and we add the action in the same way as for the toolbar.

Please note you can also add dynamic action list to your configuration file using a <ActionList> tag. For more information about this, see the plugActionList() method of the KXMLGUIClient documentation.

Change 'version' attribute of the gui tag if you changed .rc file since last install to force system cache update

CMake

Now that we're using XmlGui, we need to put the tutorial3ui.rc somewhere where KDE can find it. This means we need to install our project somewhere.

CMakeLists.txt

project(tutorial3)

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

set(tutorial3_SRCS 

 main.cpp
 mainwindow.cpp

)

kde4_add_executable(tutorial3 ${tutorial3_SRCS})

target_link_libraries(tutorial3 ${KDE4_KDEUI_LIBS})

install(TARGETS tutorial3 DESTINATION ${BIN_INSTALL_DIR}) install( FILES tutorial3ui.rc 

        DESTINATION  ${DATA_INSTALL_DIR}/tutorial3 )

This file is almost identical to the one for tutorial2 but it has two extra lines at the end. These describe where the files are to be installed. Firstly, the tutorial3 target is installed to the BIN_INSTALL_DIR then the tutorial3ui.rc file that describes the layout of the user interface is installed to the application's data directory.

Make, Install And Run

If you don't have write access to where your KDE4 installation directory, you can install it to a folder in your home directory.

To tell CMake where to install the program, set the DCMAKE_INSTALL_PREFIX switch. So to install the program to the KDE directory, do 

cmake . -DCMAKE_INSTALL_PREFIX=$KDEDIR
make install
tutorial3

Though, if you just want to install it somewhere local for testing (it's probably a bit silly to go to the effort of installing these tutorials to your KDE directory) you can do something like 

cmake . -DCMAKE_INSTALL_PREFIX=/home/kde-devel/kdetmp

which will create a KDE-like directory structure under ~/kdetmp and will install the executable to /home/kde-devel/kdetmp/bin/tutorial3.

Moving On

TODO

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