Qt SCXML Traffic Light QML Example (Static)▲
Traffic Light QML Example (Static) demonstrates how to connect to the active properties of a state in a state machine that is compiled to a class.
The UI is created using Qt Quick.
Running the Example▲
To run the example from http://, open the Welcome mode and select the example from Examples. For more information, visit http://.
Compiling the State Machine▲
We link against the Qt SCXML module by adding the following line to the .pro file:
QT += qml scxmlWe then specify the state machine to compile:
STATECHARTS = ../trafficlight-common/statemachine.scxmlThe Qt SCXML Compiler, qscxmlc, is run automatically to generate statemachine.h and statemachine.cpp, and to add them to the HEADERS and SOURCES variables for compilation.
Instantiating the State Machine▲
We instantiate the state machine as follows:
import TrafficLightStateMachine 1.0
TrafficLight {
stateMachine: TrafficLightStateMachine {
running: true
}Connecting to States▲
In the SCXML file, we specify states for each light: red, yellow, and green. In the <onentry> element, we specify the event to send when entering the state and the delay in seconds before sending the event. In the <transition> element, we specify the event that triggers the transition to the state specified by the target attribute:
<state id="red">
<onentry>
<send event="startGoingGreen" delay="3s"/>
</onentry>
<transition event="startGoingGreen" target="redGoingGreen"/>
</state>
<state id="yellow" initial="greenGoingRed">
<state id="redGoingGreen">
<onentry>
<send event="goGreen" delay="1s"/>
</onentry>
<transition event="goGreen" target="green"/>
</state>
<state id="greenGoingRed">
<onentry>
<send event="goRed" delay="1s"/>
</onentry>
<transition event="goRed" target="red"/>
</state>
</state>
<state id="green">
<onentry>
<send event="startGoingRed" delay="3s"/>
</onentry>
<transition event="startGoingRed" target="greenGoingRed"/>
</state>We connect to the states as follows:
states: [
State {
name: "Red"
when: stateMachine.red
PropertyChanges {
target: redLight
opacity: 1
}
},
State {
name: "RedGoingGreen"
when: stateMachine.redGoingGreen
PropertyChanges {
target: redLight
opacity: 1
}
PropertyChanges {
target: yellowLight
opacity: 1
}
},
State {
name: "Yellow"
when: stateMachine.yellow || stateMachine.blinking
PropertyChanges {
target: yellowLight
opacity: 1
}
},
State {
name: "Green"
when: stateMachine.green
PropertyChanges {
target: greenLight
opacity: 1
}
}
]List of Files▲
Files:
List of Files▲
-
trafficlight-qml-static/trafficlight-qml-static.cpp
-
trafficlight-qml-static/trafficlight-qml-static.pro
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trafficlight-qml-static/trafficlight-qml-static.qml
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trafficlight-qml-static/trafficlight-qml-static.qrc