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50
51#include <QApplication>
52#include <QFinalState>
53#include <QPainter>
54#include <QStateMachine>
55#include <QTimer>
56#include <QVBoxLayout>
57#include <QWidget>
58
59//! [0]
60class LightWidget : public QWidget
61{
62 Q_OBJECT
63 Q_PROPERTY(bool on READ isOn WRITE setOn)
64public:
65 LightWidget(const QColor &color, QWidget *parent = nullptr)
66 : QWidget(parent), m_color(color), m_on(false) {}
67
68 bool isOn() const
69 { return m_on; }
70 void setOn(bool on)
71 {
72 if (on == m_on)
73 return;
74 m_on = on;
75 update();
76 }
77
78public slots:
79 void turnOff() { setOn(false); }
80 void turnOn() { setOn(true); }
81
82protected:
83 void paintEvent(QPaintEvent *) override
84 {
85 if (!m_on)
86 return;
87 QPainter painter(this);
88 painter.setRenderHint(hint: QPainter::Antialiasing);
89 painter.setBrush(m_color);
90 painter.drawEllipse(x: 0, y: 0, w: width(), h: height());
91 }
92
93private:
94 QColor m_color;
95 bool m_on;
96};
97//! [0]
98
99//! [1]
100class TrafficLightWidget : public QWidget
101{
102public:
103 TrafficLightWidget(QWidget *parent = nullptr)
104 : QWidget(parent)
105 {
106 QVBoxLayout *vbox = new QVBoxLayout(this);
107 m_red = new LightWidget(Qt::red);
108 vbox->addWidget(m_red);
109 m_yellow = new LightWidget(Qt::yellow);
110 vbox->addWidget(m_yellow);
111 m_green = new LightWidget(Qt::green);
112 vbox->addWidget(m_green);
113 QPalette pal = palette();
114 pal.setColor(acr: QPalette::Window, acolor: Qt::black);
115 setPalette(pal);
116 setAutoFillBackground(true);
117 }
118
119 LightWidget *redLight() const
120 { return m_red; }
121 LightWidget *yellowLight() const
122 { return m_yellow; }
123 LightWidget *greenLight() const
124 { return m_green; }
125
126private:
127 LightWidget *m_red;
128 LightWidget *m_yellow;
129 LightWidget *m_green;
130};
131//! [1]
132
133//! [2]
134QState *createLightState(LightWidget *light, int duration, QState *parent = nullptr)
135{
136 QState *lightState = new QState(parent);
137 QTimer *timer = new QTimer(lightState);
138 timer->setInterval(duration);
139 timer->setSingleShot(true);
140 QState *timing = new QState(lightState);
141 QObject::connect(sender: timing, signal: &QAbstractState::entered, receiver: light, slot: &LightWidget::turnOn);
142 QObject::connect(sender: timing, signal: &QAbstractState::entered, receiver: timer, slot: QOverload<>::of(ptr: &QTimer::start));
143 QObject::connect(sender: timing, signal: &QAbstractState::exited, receiver: light, slot: &LightWidget::turnOff);
144 QFinalState *done = new QFinalState(lightState);
145 timing->addTransition(obj: timer, signal: &QTimer::timeout, target: done);
146 lightState->setInitialState(timing);
147 return lightState;
148}
149//! [2]
150
151//! [3]
152class TrafficLight : public QWidget
153{
154public:
155 TrafficLight(QWidget *parent = nullptr)
156 : QWidget(parent)
157 {
158 QVBoxLayout *vbox = new QVBoxLayout(this);
159 TrafficLightWidget *widget = new TrafficLightWidget;
160 vbox->addWidget(widget);
161 vbox->setContentsMargins(QMargins());
162
163 QStateMachine *machine = new QStateMachine(this);
164 QState *redGoingYellow = createLightState(light: widget->redLight(), duration: 3000);
165 redGoingYellow->setObjectName("redGoingYellow");
166 QState *yellowGoingGreen = createLightState(light: widget->yellowLight(), duration: 1000);
167 yellowGoingGreen->setObjectName("yellowGoingGreen");
168 redGoingYellow->addTransition(obj: redGoingYellow, signal: &QState::finished, target: yellowGoingGreen);
169 QState *greenGoingYellow = createLightState(light: widget->greenLight(), duration: 3000);
170 greenGoingYellow->setObjectName("greenGoingYellow");
171 yellowGoingGreen->addTransition(obj: yellowGoingGreen, signal: &QState::finished, target: greenGoingYellow);
172 QState *yellowGoingRed = createLightState(light: widget->yellowLight(), duration: 1000);
173 yellowGoingRed->setObjectName("yellowGoingRed");
174 greenGoingYellow->addTransition(obj: greenGoingYellow, signal: &QState::finished, target: yellowGoingRed);
175 yellowGoingRed->addTransition(obj: yellowGoingRed, signal: &QState::finished, target: redGoingYellow);
176
177 machine->addState(state: redGoingYellow);
178 machine->addState(state: yellowGoingGreen);
179 machine->addState(state: greenGoingYellow);
180 machine->addState(state: yellowGoingRed);
181 machine->setInitialState(redGoingYellow);
182 machine->start();
183 }
184};
185//! [3]
186
187//! [4]
188int main(int argc, char **argv)
189{
190 QApplication app(argc, argv);
191
192 TrafficLight widget;
193 widget.resize(w: 110, h: 300);
194 widget.show();
195
196 return app.exec();
197}
198//! [4]
199
200#include "main.moc"
201

source code of qtbase/examples/widgets/statemachine/trafficlight/main.cpp