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| == Qt Designer User Interfaces in KDE ==
| | {{Note|This is now located at https://community.kde.org/Get_Involved/development/Tutorials/Using_Qt_Designer}} |
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| In this tutorial, we will explore how to programatically insert user interfaces
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| (UIs) created with Qt Designer, into your KDE project.
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| == Designing the UI ==
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| [http://www.trolltech.com/products/qt/features/designer Qt Designer] is a
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| graphical program which allows you to easily build user interfaces, using an
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| intuitive "drag n drop" interface. Designer has its own excellent
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| [http://doc.trolltech.com/4.3/designer-manual.html user documentation].
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| It might make sense to provide a brief example of using Designer here, but
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| for now this article will leave most of that to the Designer manual itself.
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| == Adding the UI File to Your KDE Project ==
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| For our purposes, the most important part of using Designer is the
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| <tt>*.ui</tt> file that it creates. This is simply an XML file that
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| encodes the user interface in a machine-readable (and human-readable!) way.
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| Let's imagine that you've created a UI named "MyDialog" with Designer, and
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| saved it as the file <tt>mydialog.ui</tt>. To add this UI to your KDE
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| project, simply add a command like the following to your CMakeLists.txt file:
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| <code>
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| kde4_add_ui_files(myapp_SRCS mydialog.ui)
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| </code>
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| Replace "<tt>myapp_SRCS</tt>" with the name of the main block in
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| your CMakeLists.txt file, defining all of the source code files. It is usually the
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| name of your application, with "<tt>_SRCS</tt>" appended.
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| When you do this, the build system will run the Qt program <tt>uic</tt>
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| on <tt>mydialog.ui</tt>, to auto-generate a C++ header file that
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| defines the UI. The generated file will be named <tt>ui_mydialog.h</tt>.
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| == Using the UI in Your Code ==
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| The <tt>ui_mydialog.h</tt> file defines a class named
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| "<tt>Ui_MyDialog</tt>", that contains all of the widgets you created in
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| Designer as public members of the class. It also contains the public function
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| "<tt>setupUi(QWidget *parent)</tt>", which instantiates all of the widgets,
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| sets up their properties, and inserts them into layout managers, all according
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| to what you specified in Designer.
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| Note that <tt>setupUi()</tt> takes a <tt>QWidget*</tt> | |
| argument. This argument represents the parent container widget, into which
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| all of the widgets in your UI will be inserted. In other words,
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| '''<tt>Ui_MyDialog</tt> is not itself derived from QWidget''', and
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| '''it does not contain a toplevel widget itself'''. You have to supply the toplevel widget
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| when you call <tt>setupUi()</tt>. This is an important point.
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| One more important semantic detail: the <tt>Ui_MyDialog</tt> class
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| also creates a <tt>Ui</tt> namespace, which simply creates an alias
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| for the class. So you can use <tt>Ui::MyDialog</tt> to refer to the
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| same class.
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| Now, on to actually using the generated UI in your code. The Qt documentation
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| shows three ways of [http://doc.trolltech.com/latest/designer-using-a-component.html how to use ui-files];
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| here only the ''direct approach'' is discussed. The goal is to create a KDialog
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| which embeds the UI from the ui-file. First, we have to subclass MyDialog from
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| KDialog and add a pointer to Ui::MyDialog. The header file of
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| "<tt>mydialog.h</tt>" looks like the following:
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| <code cppqt>
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| #ifndef MYDIALOG_H
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| #define MYDIALOG_H
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| #include <KDialog>
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| namespace Ui {
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| // forward declaration of Ui::MyDialog. This way we work
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| // around the #include "ui_mydialog.h"
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| class MyDialog;
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| }
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| class MyDialog : public KDialog
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| {
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| Q_OBJECT
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| public:
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| MyDialog( QWidget *parent=0 );
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| ~MyDialog();
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| private slots:
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| void slotButtonClicked();
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| private:
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| // pointer to the ui. we can access all gui elements
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| // specified in Designer. If mydialog.ui contains a
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| // button "myButton", we will be able to access it
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| // with ui->myButton in the cpp file.
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| Ui::MyDialog *ui;
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| };
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| #endif
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| </code>
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| Now we are going to look at the implementation of MyDialog, which is in the file
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| "<tt>mydialog.cpp</tt>".
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| <code cppqt>
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| #include <KLocale>
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| #include <KMessageBox>
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| // include the header file of the dialog
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| #include "mydialog.h"
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| // include the automatically generated header file for the ui-file
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| #include "ui_mydialog.h"
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| MyDialog::MyDialog( QWidget *parent )
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| : KDialog( parent )
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| {
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| QWidget *widget = new QWidget( this );
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| // create the user interface, the parent widget is "widget"
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| ui = new Ui::MyDialog();
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| ui->setupUi(widget); // this is the important part
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| // set the widget with all its gui elements as the dialog's
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| // main widget
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| setMainWidget( widget );
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| // other KDialog options
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| setCaption( i18n("This is my Dialog window!") );
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| setButtons( KDialog::Close );
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| // Example Signal/Slot connection using widgets in your UI.
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| // Note that you have to prepend "ui->" when referring
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| // to your UI elements.
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| connect( ui->myButton, SIGNAL( clicked() ),
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| this, SLOT( slotButtonClicked() ) );
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| }
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| MyDialog::~MyDialog()
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| {
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| // no need to delete the user interface.
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| // QObject derived classes automatically delete their children.
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| } | |
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| void MyDialog::slotButtonClicked()
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| {
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| KMessageBox::information( this,
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| i18n("You pressed the button!" ),
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| i18n( "Hooray!" ) );
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| } | |
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| #include "mydialog.moc"
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| </code>
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| So, basically, we create a new Ui::MyDialog and then call
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| <tt>ui->setupUi(widget)</tt> in the constructor of <tt>MyDialog</tt>. This
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| places the UI elements into the given widget. Then we set the parent-widget
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| as the KDialog's main widget. We can then interact with all of the UI elements
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| by prepending "<tt>ui-></tt>" to their names, just like it is often done
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| with the prefix "<tt>m_</tt>".
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| == Final Thoughts ==
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| The cascade of files and classes in this tutorial may seem daunting at
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| first, but the naming scheme layed out here has one nice intuitive
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| feature: the source code files that you will be editing directly (either as
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| text or with Designer) are all named with the same scheme:
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| * '''mydialog.ui''': the user interface, created with Designer
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| * '''ui_mydialog.h''': auto-generated by moc, Qt's meta object compiler
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| * '''mydialog.h/cpp''': the dialog implementation
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| The steps in short are
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| # create <tt>mydialog.ui</tt>
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| # create <tt>mydialog.h/cpp</tt>
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| # add forward declaration and member variable Ui::MyDialog *ui; in <tt>mydialog.h</tt>
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| # call <tt>ui = new Ui::MyDialog(); ui->setupUi(widget);</tt>
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| # use the ui with <tt>ui-></tt>
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| == Qt Documentation ==
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| The Qt documentation contains a good article about
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| [http://doc.trolltech.com/latest/designer-using-a-component.html Using a Component in Your Application].
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| [[Category:C++]]
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| [[Category:KDE4]]
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