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/****************************************************************************
**
** Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the $MODULE$ of the Qt Toolkit.
**
** $TROLLTECH_DUAL_LICENSE$
**
****************************************************************************/
/*!
\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 a setOn() function to turn the light on or off. It paints itself
in the color that's passed to the constructor.
\snippet examples/statemachine/trafficlight/main.cpp 2
The TrafficLightWidget class represents the visual part of the traffic
light; it's a widget that contains three lights, and provides accessor
functions for these.
\snippet examples/statemachine/trafficlight/main.cpp 1
The LightState class represents a state that turns a light on when the
state is entered, and off when the state is exited. The class is a timer,
and as we shall see the timeout is used to transition from one LightState
to another.
\snippet examples/statemachine/trafficlight/main.cpp 3
The TrafficLight class combines the TrafficLightWidget with control flow
based on the LightState class. 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.
\snippet examples/statemachine/trafficlight/main.cpp 4
The main() function constructs a TrafficLight and shows it.
*/
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