// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
 * \title Qt Wayland Compositor Examples - Overview Compositor
 * \example overview-compositor
 * \brief Overview Compositor shows how to switch between clients in a grid.
 *
 * \section1 Introduction
 *
 * Overview Compositor demonstrates selecting and activating an application
 * from a grid of currently connected clients.
 *
 * \image overview-compositor.jpg
 *
 * For an introduction to the basic principles of creating a \l{Qt Wayland Compositor} with Qt,
 * see the \l{Qt Wayland Compositor Examples - Minimal QML}{Minimal QML example}.
 *
 * \section1 Application Grid
 *
 * In this example, the compositor supports two different modes of operation:
 *
 * \list
 *   \li A \e fullscreen mode, where a single application window occupies the whole compositor
 *       window and is interactable.
 *   \li An \e overview mode, where all application windows are visible in a grid. Clicking on a
 *       window in the grid causes it to be selected. The compositor enters fullscreen mode,
 *       showing the selected application window.
 * \endlist
 *
 * When a client connects to the compositor and creates a top-level surface, the surface will be
 * connected to a \l{Shell Extensions - Qt Wayland Compositor}{shell extension}. The example only
 * supports the \l{XdgShell} extension, so the client will connect to this.
 *
 * \snippet overview-compositor/main.qml XdgShell
 *
 * For each surface, we tell the client to configure it as fullscreen. In addition, the surfaces
 * are added to a \l ListModel for easy access.
 *
 * This model is used by a \l Repeater to create \l{ShellSurfaceItem}{ShellSurfaceItems} inside
 * a \l{Grid}. The \l Grid component positions the items in a grid.
 *
 * \snippet overview-compositor/main.qml toplevels repeater
 *
 * For each of the items, we create a \l MouseArea which covers the item and intercepts all mouse
 * and touch input. This is only active when the compositor is in \e{overview} mode, and activates
 * the application that was clicked.
 *
 * When the compositor goes into fullscreen mode, the same \l Grid component is used, but is scaled
 * and translated into a position where the single selected cell fills the compositor's window. The
 * idea is to "zoom in" on the selected cell, allowing the user to interact with the application it
 * contains.
 *
 * \snippet overview-compositor/main.qml zoom transform
 *
 * At the bottom side of the window, there is a button which toggles between the modes. This can
 * be used to bring back the application grid while the compositor is in fullscreen mode.
 *
 * This example shows one way to have the compositor visualize clients in different modes. Another
 * way to achieve similar effects is to create multiple Qt Quick items that refer to the same
 * surface. See \l{Qt Wayland Compositor Examples - Multi Output}{the Multi Output example} for a
 * demonstration.
 *
 * \ingroup qtwaylandcompositor-examples
 */
