/*
    quick-event-handling.qdoc

    This file is part of the GammaRay documentation.

    Copyright (C) 2016-2021 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com
    Author: Volker Krause <volker.krause@kdab.com>

    Licensees holding valid commercial KDAB GammaRay licenses may use this file in
    accordance with GammaRay Commercial License Agreement provided with the Software.

    Contact info@kdab.com if any conditions of this licensing are not clear to you.

    This work is also licensed under the Creative Commons Attribution-ShareAlike 4.0
    International License. See <https://creativecommons.org/licenses/by-sa/4.0/>.
*/

/*!
    \example quick-event-handling
    \title Qt Quick Event Handling
    \brief Investigate issues regarding Qt Quick input events.
    \ingroup examples-gammaray

    This examples shows GammaRay's capabilities for analyzing \l{Qt Quick} event handling issues.

    \section1 Problem

    The example application shows a simple Qt Quick button. Clicking the button is supposed to
    emit a debug message acknowledging the click.

    \snippet quick-event-handling/quick-event-handling.qml Button setup

    However, you can observe that this only works on the left side of the button, on the right side
    clicks have no effect.

    \section1 Investigation

    There are several aspects of this problem that can be analyzed with GammaRay.

    \section2 Qt Quick element picking

    Open the \l{Qt Quick 2 Inspector} and select the element picking tool above the scene view on the lower left.
    Clicking on to the view will select the element at that location. You can notice that picking on the left
    side of the button will select the button as expected (or one of its internal elements), but picking on
    the right side selects a second, invisible button.

    \snippet quick-event-handling/quick-event-handling.qml Hidden button

    This hidden button consumes the events and thus breaks our example.

    \section2 Live property editing

    Selecting the hidden button in the \l{Qt Quick 2 Inspector} or \l{Object Browser} tools will show the \l{Properties}
    view on the right. In there we can investigate why the hidden button consumes events, and test our theory by
    changing properties in the running application.

    In our case we will notice that the button is not actually hidden (the visible property is still true), it is
    merely set to be fully transparent (the opacity property is 0). If we change its visible property to false, our
    example works as expected, that is clicks on the right half of the button work as well.
*/