qt-creator/doc/src/widgets/qtdesigner-app-tutorial.qdoc

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/*!
    \contentspage index.html
    \page creator-writing-program.html
    \nextpage creator-project-managing.html

    \title Creating a Qt Widget Based Application

    This tutorial describes how to use \QC to create a small Qt application,
    Text Finder. It is a simplified version of the  QtUiTools
    \l{http://qt-project.org/doc/qt-4.8/uitools-textfinder.html}{Text Finder}
    example. The application user interface is constructed from Qt widgets by
    using \QD. The application logic is written in C++ by using the code editor.

    \image qtcreator-textfinder-screenshot.png

    \section1 Creating the Text Finder Project

    \list 1

        \o  Select \gui{File > New File or Project > Applications > Qt Gui
            Application > Choose}.

            \image qtcreator-new-qt-gui-application.png "New File or Project dialog"

            The \gui{Introduction and Project Location} dialog opens.

            \image qtcreator-intro-and-location-qt-gui.png "Introduction and Project Location dialog"

        \o  In the \gui{Name} field, type \bold {TextFinder}.

        \o  In the \gui {Create in} field, enter the path for the project files.
            For example, \c {C:\Qt\examples}, and then click \gui{Next}.

            The \gui {Target Setup} dialog opens.

            \image qtcreator-new-project-qt-versions-qt-gui.png "Target Setup dialog"

        \o  Select build targets for your project,
            and click \gui{Next}.

            \note If only one target is specified in \gui Tools > \gui Options >
            \gui {Build & Run} > \gui Targets, this dialog is
            skipped.

            The \gui{Class Information} dialog opens.

            \image qtcreator-class-info-qt-gui.png "Class Information dialog"

        \o  In the \gui{Class name} field, type \bold {TextFinder} as the class
            name.

        \o  In the \gui{Base class} list, select \bold {QWidget} as the base
            class type.

           \note The \gui{Header file}, \gui{Source file} and \gui{Form file}
            fields are automatically updated to match the name of the class.

        \o  Click \gui{Next}.

            The \gui{Project Management} dialog opens.

            \image qtcreator-new-project-summary-qt-gui.png "Project Management dialog"

        \o  Review the project settings, and click \gui{Finish} to create the
            project.

    \endlist

    \note The project opens in the \gui Edit mode, and these instructions are
    hidden. To return to these instructions, open the \gui Help mode.

    The TextFinder project now contains the following files:

    \list

        \o  textfinder.h
        \o  textfinder.cpp
        \o  main.cpp
        \o  textfinder.ui
        \o  textfinder.pro

    \endlist

    \image qtcreator-textfinder-contents.png "TextFinder project contents"

    The .h and .cpp files come with the necessary boiler plate code.
    The .pro file is complete.

    \section1 Filling in the Missing Pieces

    Begin by designing the user interface and then move on to filling
    in the missing code. Finally, add the find functionality.

    \section2 Designing the User Interface

    \image qtcreator-textfinder-ui.png "Text Finder UI"

    \list 1

        \o  In the \gui{Editor} mode, double-click the textfinder.ui file in the
            \gui{Projects} view to launch the integrated \QD.

        \o  Drag and drop the following widgets to the form:

        \list

            \o  \gui{Label} (QLabel)
            \o  \gui{Line Edit} (QLineEdit)
            \o  \gui{Push Button} (QPushButton)

        \endlist

        \image qtcreator-textfinder-ui-widgets.png "Adding widgets to Text Finder UI"

        \note To easily locate the widgets, use the search box at the top of the
        \gui Sidebar. For example, to find the \gui Label widget, start typing
        the word \bold label.

        \image qtcreator-texfinder-filter.png "Filter field"

        \o  Double-click the \gui{Label} widget and enter the text
            \bold{Keyword}.

        \o  Double-click the \gui{Push Button} widget and enter the text
            \bold{Find}.

        \o  In the \gui Properties pane, change the \gui objectName to
            \bold findButton.

            \image qtcreator-textfinder-objectname.png "Changing object names"

        \o  Press \key {Ctrl+A} to select the widgets and click
            \gui{Lay out Horizontally} (or press \gui{Ctrl+H}) to apply a
            horizontal layout (QHBoxLayout).

            \image qtcreator-texfinder-ui-horizontal-layout.png "Applying horizontal layout"

        \o  Drag and drop a \gui{Text Edit} widget (QTextEdit) to the form.

        \o  Select the screen area and click \gui{Lay out Vertically} (or press
            \gui{Ctrl+L}) to apply a vertical layout (QVBoxLayout).

            \image qtcreator-textfinder-ui.png "Text Finder UI"

            Applying the horizontal and vertical layouts ensures that the
            application UI scales to different screen sizes.

        \o  To call a find function when users press the \gui Find button, you
            use the Qt signals and slots mechanism. A signal is emitted when a
            particular event occurs and a slot is a function that is called in
            response to a particular signal. Qt widgets have predefined signals
            and slots that you can use directly from \QD. To add a slot for the
            find function:

            \list

                \o  Right-click the \gui Find button to open a context-menu.

                \o  Select \gui {Go to Slot > clicked()}, and then select
                    \gui OK.

                    A private slot, \c{on_findButton_clicked()}, is added to the
                    header file, textfinder.h and a private function,
                    \c{TextFinder::on_findButton_clicked()}, is added to the
                    source file, textfinder.cpp.

            \endlist

        \o  Press \gui{Ctrl+S} to save your changes.

    \endlist

    For more information about designing forms with \QD, see the
    \l{http://qt-project.org/doc/qt-4.8/designer-manual.html}{Qt Designer Manual}.

    \section2 Completing the Header File

    The textfinder.h file already has the necessary #includes, a constructor,
    a destructor, and the \c{Ui} object. You need to add a private function,
    \c{loadTextFile()}, to read and display the contents of the input text file
    in the QTextEdit.

    \list 1

        \o  In the \gui{Projects} pane in the \gui {Edit view}, double-click the
            \c{textfinder.h} file to open it for editing.

        \o  Add a private function to the \c{private} section, after the
            \c{Ui::TextFinder} pointer, as illustrated by the following code
            snippet:

            \snippet examples/textfinder/textfinder.h 0

    \endlist

    \section2 Completing the Source File

    Now that the header file is complete, move on to the source file,
    textfinder.cpp.

    \list 1

        \o  In the \gui{Projects} pane in the \gui Edit view, double-click the
            textfinder.cpp file to open it for editing.

        \o  Add code to load a text file using QFile, read it with QTextStream,
            and then display it on \c{textEdit} with
            \l{http://qt-project.org/doc/qt-4.8/qtextedit.html#plainText-prop}
            {setPlainText()}.
            This is illustrated by the following code snippet:

            \snippet examples/textfinder/textfinder.cpp 0

        \o  To use QFile and QTextStream, add the following #includes to
            textfinder.cpp:

            \snippet examples/textfinder/textfinder.cpp 1

        \o  For the \c{on_findButton_clicked()} slot, add code to extract the
            search string and use the
            \l{http://qt-project.org/doc/qt-4.8/qtextedit.html#find}{find()}
            function
            to look for the search string within the text file. This is
            illustrated by the following code snippet:

            \snippet examples/textfinder/textfinder.cpp 2

        \o  Once both of these functions are complete, add a line to call
            \c{loadTextFile()} in the constructor, as illustrated by the
            following code snippet:

            \snippet examples/textfinder/textfinder.cpp 3

    \endlist

    The \c{on_findButton_clicked()} slot is called automatically in
    the uic generated ui_textfinder.h file by this line of code:

    \code
    QMetaObject::connectSlotsByName(TextFinder);
    \endcode

    \section2 Creating a Resource File

    You need a resource file (.qrc) within which you embed the input
    text file. The input file can be any .txt file with a paragraph of text.
    Create a text file called input.txt and store it in the textfinder
    folder.

    To add a resource file:

    \list 1

        \o  Select \gui{File > New File or Project > Qt > Qt Resource File >
            Choose}.

            \image qtcreator-add-resource-wizard.png "New File or Project dialog"

            The \gui {Choose the Location} dialog opens.

            \image qtcreator-add-resource-wizard2.png "Choose the Location dialog"

        \o  In the \gui{Name} field, enter \bold{textfinder}.

        \o  In the \gui{Path} field, enter \c{C:\Qt\examples\TextFinder},
            and click \gui{Next}.

            The \gui{Project Management} dialog opens.

            \image qtcreator-add-resource-wizard3.png "Project Management dialog"


        \o  In the \gui{Add to project} field, select \bold{TextFinder.pro}
            and click \gui{Finish} to open the file in the code editor.

        \o  Select \gui{Add > Add Prefix}.

        \o  In the \gui{Prefix} field, replace the default prefix with a slash
            (/).

        \o  Select \gui{Add > Add Files}, to locate and add input.txt.

            \image qtcreator-add-resource.png "Editing resource files"

    \endlist

    \section1 Compiling and Running Your Program

    Now that you have all the necessary files, click the
    \inlineimage qtcreator-run.png
    button to compile and run your program.

*/