qtquick-debugger-example.qdoc 4.79 KB
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/****************************************************************************
**
** This file is part of Qt Creator
**
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** Copyright (c) 2012 Nokia Corporation and/or its subsidiary(-ies).
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**
** Contact: Nokia Corporation (qt-info@nokia.com)
**
**
** GNU Free Documentation License
**
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of this
** file.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
****************************************************************************/

// **********************************************************************
// NOTE: the sections are not ordered by their logical order to avoid
// reshuffling the file each time the index order changes (i.e., often).
// Run the fixnavi.pl script to adjust the links to the index order.
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/*!
    \contentspage index.html
    \previouspage creator-debugging-example.html
    \page creator-qml-debugging-example.html
    \nextpage creator-debugger-operating-modes.html

    \title Debugging a Qt Quick Example Application

    This section uses the
    \l{http://doc.qt.nokia.com/4.7/demos-declarative-samegame.html}{Same Game}
    demo application to illustrate how to debug Qt Quick applications in the
    \gui Debug mode.

    For more information about all the options you have, see
    \l{Debugging Qt Quick Projects}.

    The Same Game demo shows how to write a game in QML, using JavaScript for
    all the game logic. Open the demo project in \QC to debug it:

    \list 1

        \o  To look at the code that starts a new game, place a breakpoint in
            samegame.qml by clicking between the line number and the window
            border on the line where where the \c startNewGame() function is
            called.

            \image qtquick-example-setting-breakpoint1.png

            The red circle indicates that a breakpoint is now set on that line
            number.

        \o  Select \gui {Debug > Start Debugging > Start Debugging} or press
            \key{F5}.

        \o  Once the Same Game application starts, click the \gui {New Game}
            button to start a new game.

        \o  When the debugger hits the breakpoint, it interrupts the
            application. \QC displays the nested function calls leading to the
            current position as a call stack trace. To view the stack, select
            the \gui Stack tab.

            \image qtquick-example-setting-breakpoint2.png

        \o  Click the
            \inlineimage qml-inspector-step-into.png
            (\gui {Step Into}) button on the toolbar or press \key F11 to step
            into the code in the stack. The samegame.js file opens in the code
            editor at the function that starts a new game.

            \image qtquick-example-stack.png

        \o  Examine the local variables in the \gui {Locals and Expressions}
            view. Step through the code to see how the information changes in
            the view.

        \o  Add a breakpoint at the end of the \c {startNewGame()} function, and
            click \inlineimage qtcreator-debugging-continue.png
            (\gui Continue) to hit the breakpoint.

            \image qtquick-example-setting-breakpoint3.png

        \o  To execute JavaScript commands in the current context, select the
            \gui {QML Script Console} tab.

        \o  To change the score to 1000, enter \c{gameCanvas.score = 1000}
            in the console.

            \image qtquick-example-script-console.png

        \o  To remove a breakpoint, right-click it and select
            \gui {Delete Breakpoint}.

        \o  Select the \gui {QML Inspector} tab to explore the object structure
            at runtime:

            \image qtquick-example-qml-inspector.png

        \o  Click
            \inlineimage qml-inspector-app-on-top.png
            (\gui {Show Application on Top}) to keep the application visible
            while you interact with the debugger.

        \o  Click
            \inlineimage qml-inspector-select-button.png
            (\gui Select) to activate selection mode and then click the
            \gui {New Game} button to move into the \gui newGameButton component
            in the \gui {QML Script Console} and the code editor.

            \image qtquick-example-property-values.png

        \o  In the \gui {QML Inspector} view, double-click the value of the
            \c text property to change it temporarily from \gui {Quit} to
            \gui {End Game}.

            When you select an element, the cursor moves to it in the code
            editor, where you can change the value permanently.

    \endlist

*/