Hello World Using QtScript

This article shows how to use QtScript through a simple "Helloworld" example. It demonstrates how to embed a script engine into the application, how to evaluate a script, and how to process the result of the evaluation.

Article Metadata

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Tested with

Devices(s): Emulator

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Compatibility

Platform(s): S60 3rd Edition, S60 5th Edition, Symbian^3, Maemo

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Article

Keywords: QtScript, QApplication, QPushButton, QMessageBox

Created: chintandave_er (05 Nov 2010)

Last edited: hamishwillee (11 Oct 2012)

Source

#include <QApplication>
#include <QMessageBox>
#include <QPushButton>
#include <QtScript>
 
 
int main(int argc, char *argv[])
{
    // load the script file to evaluate from a resource
    Q_INIT_RESOURCE(helloscript);
 
    QApplication app(argc, argv);
    QScriptEngine engine;
 
    // push button is created and exported to the script environment as a global variable, button.
    // Scripts will be able to access properties, signals and slots of the button as properties of the button script object
    QPushButton button;
    QScriptValue scriptButton = engine.newQObject(&button);
    engine.globalObject().setProperty("button", scriptButton);
 
    // read the contents of the script file
    QString fileName(":/helloscript.js");
    QFile scriptFile(fileName);
    scriptFile.open(QIODevice::ReadOnly);
    QTextStream stream(&scriptFile);
    QString contents = stream.readAll();
    scriptFile.close();
 
 
    // script evaluated.
    QScriptValue result = engine.evaluate(contents, fileName);
 
 
    // If any Error, Display line number and error in a message box.
    if (result.isError()) {
        QMessageBox::critical(0, "Hello Script",
                              QString::fromLatin1("%0:%1: %2")
                              .arg(fileName)
                              .arg(result.property("lineNumber").toInt32())
                              .arg(result.toString()));
        return -1;
    }
 
    // App Event loop is entered if everything went well
    return app.exec();
}

Script File (helloscript.js)

// set the text and stylesheet of button in script
button.text = 'Hello World!';
button.styleSheet = 'font-style: italic';
button.show();

Project file (helloscript.pro)

You need following linkage in your .pro file.

QT += script
RESOURCES += helloscript.qrc
SOURCES += main.cpp
 
# install
target.path = $$[QT_INSTALL_EXAMPLES]/script/helloscript
sources.files = $$SOURCES $$HEADERS $$RESOURCES $$FORMS helloscript.pro
sources.path = $$[QT_INSTALL_EXAMPLES]/script/helloscript
INSTALLS += target sources
 
symbian: include($$PWD/../../symbianpkgrules.pri)

Resource file (helloscript.qrc)

Add helloscript.js file in Resource file.

 <RCC>
     <qresource prefix="/" >
         <file>helloscript.js</file>
     </qresource>
 </RCC>

References

• QtScript