- Qt 6.4
- Qt SCXML
- Qt SCXML Examples
- Qt SCXML Media Player QML Example (Static)
- Qt 6.4.2 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 lines to the example's build files.

##### .pro when using qmake:

     QT += widgets scxml

We then specify the state machine to compile:

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

##### CMakeLists.txt when using cmake:

     find_package(Qt6 REQUIRED COMPONENTS Core Gui Scxml Widgets)

     target_link_libraries(mediaplayer-widgets-static PUBLIC
         Qt6::Core
         Qt6::Gui
         Qt6::Scxml
         Qt6::Widgets
     )

We then specify the state machine to compile:

     qt6_add_statecharts(mediaplayer-widgets-static
         ../mediaplayer-common/mediaplayer.scxml
     )

The statechart directives STATECHARTS or qt6_add_statecharts invoke the Qt SCXML Compiler, `qscxmlc`, which is run automatically to generate a header and a source file, which are then added appropriately 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