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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.1, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \example statemachine/trafficlight
+ \title Traffic Light Example
+
+ The Traffic Light example shows how to use \l{The State Machine Framework}
+ to implement the control flow of a traffic light.
+
+ \image trafficlight-example.png
+
+ In this example we write a TrafficLightWidget class. The traffic light has
+ three lights: Red, yellow and green. The traffic light transitions from
+ one light to another (red to yellow to green to yellow to red again) at
+ certain intervals.
+
+ \snippet examples/statemachine/trafficlight/main.cpp 0
+
+ The LightWidget class represents a single light of the traffic light. It
+ provides an \c on property and two slots, turnOn() and turnOff(), to turn
+ the light on and off, respectively. The widget paints itself in the color
+ that's passed to the constructor.
+
+ \snippet examples/statemachine/trafficlight/main.cpp 1
+
+ The TrafficLightWidget class represents the visual part of the traffic
+ light; it's a widget that contains three lights arranged vertically, and
+ provides accessor functions for these.
+
+ \snippet examples/statemachine/trafficlight/main.cpp 2
+
+ The createLightState() function creates a state that turns a light on when
+ the state is entered, and off when the state is exited. The state uses a
+ timer, and as we shall see the timeout is used to transition from one
+ LightState to another. Here is the statechart for the light state:
+
+ \img trafficlight-example1.png
+ \omit
+ \caption This is a caption
+ \endomit
+
+ \snippet examples/statemachine/trafficlight/main.cpp 3
+
+ The TrafficLight class combines the TrafficLightWidget with a state
+ machine. The state graph has four states: red-to-yellow, yellow-to-green,
+ green-to-yellow and yellow-to-red. The initial state is red-to-yellow;
+ when the state's timer times out, the state machine transitions to
+ yellow-to-green. The same process repeats through the other states.
+ This is what the statechart looks like:
+
+ \img trafficlight-example2.png
+ \omit
+ \caption This is a caption
+ \endomit
+
+ \snippet examples/statemachine/trafficlight/main.cpp 4
+
+ The main() function constructs a TrafficLight and shows it.
+
+*/