Qt 5.13 | Qt SCXML | Qt SCXML Media Player QML Example (Static)

Qt 5.13.2 Reference Documentation

# Qt SCXML Media Player QML Example (Static)

A Qt Quick application that sends data to and receives it from a compiled ECMAScript data model.

Media Player QML Example (Static) demonstrates how to access data from an ECMAScript data model that is compiled into a C++ class.

The UI is created using Qt Quick.

#### Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

#### Using the ECMAScript Data Model

We specify the data model as a value of the datamodel attribute of the `<scxml>` element in mediaplayer-common/mediaplayer.scxml:

      <scxml
          xmlns="http://www.w3.org/2005/07/scxml"
          version="1.0"
          name="MediaPlayerStateMachine"
          initial="stopped"
          datamodel="ecmascript"
      >
          <datamodel>
              <data id="media"/>
          </datamodel>

#### Compiling the State Machine

We link against the Qt SCXML module by adding the following line to the .pro file:

      QT += widgets scxml

We then specify the state machine to compile:

      STATECHARTS = ../mediaplayer-common/mediaplayer.scxml

The 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 generated `MediaPlayerStateMachine` class in mediaplayer-qml-static.cpp:

      #include "mediaplayer.h"

      int main(int argc, char *argv[])
      {
          QGuiApplication app(argc, argv);

          qmlRegisterType<MediaPlayerStateMachine>("MediaPlayerStateMachine", 1, 0, "MediaPlayerStateMachine");

          QQmlApplicationEngine engine;
          engine.load(QUrl(QStringLiteral("qrc:///mediaplayer-qml-static.qml")));
          if (engine.rootObjects().isEmpty())
              return -1;

          return app.exec();
      }

Example project @ code.qt.io