passing QByteArray in arg with QScriptEngine

kickoune103

hello,
i will try to use QScriptEngine to write function to Read Array and write array to change Trame for example with qtscript user.
i have read lot of documentation.

i will try this:
for the moment, i have QByteArray in my software, to check trameProtocol by script.

QByteArray l_ByteArray ="01";
QVariant l_varByteArray = l_ByteArray;
QScriptValue l_var = m_engine.newVariant(l_varByteArray);
QScriptValue m_fct_checksum = m_engine.evaluate("( \n function cal_crc(pTrame) \n { return pTrame[0]; \n } \n)");
qDebug() << m_fct_checksum.call(QScriptValue(),l_var).toInteger();
/* works  can read if i return element of array, but not can t modify by script , not have properti length in script not work

if call with newArray(), not have to access to property length */

i don't understand i will write custom class like this
https://doc.qt.io/archives/qt-4.8/qt-script-customclass-example.html

or i have automatic conversion not works?

thanks

Gojir4

@kickoune103 Hi,

Here is the function I'm using to convert JsArray to QByteArray and opposite.

static QByteArray qByteArrayFromJSArray(const QScriptValue &jsArray)
{
    QByteArray ba;
    if(jsArray.isNull() || !jsArray.isArray())
        return ba;

    QScriptValueIterator it(jsArray);
    bool indexOk;
    while (it.hasNext()) {
        it.next();
        it.name().toUInt(&indexOk);
        //take only property name composed by a number. Otherwise this is not a data value
        if(indexOk)
            ba.append(static_cast<quint8>(it.value().toUInt16()));
    }
    return ba;
}

static QScriptValue jsArrayFromQByteArray(const QByteArray &ba, QScriptEngine *jsEngine)
{
    QScriptValue array = jsEngine->newArray(ba.size());
    for(int i = 0; i < ba.size(); i++)
        array.setProperty(i, ba.at(i) & 0xFF);

    return array;
}

Hope this helps

kickoune103

ok i saw,
but i have use this with this script:
"( \n function cal_crc(pTrame) \n { return pTrame.length; \n } \n)"

QScriptValue l_var = m_engine.newArray(2);
l_var.setProperty( 0,QScriptValue('0') );
l_var.setProperty( 1,QScriptValue('1') );
qDebug() << l_var.toVariant();
qDebug() << m_fct_checksum.call(QScriptValue(),l_var).toInteger();

//console
QVariant(QVariantList, (QVariant(int, 48), QVariant(int, 49)))
0

like writing previously, don't modify pTrame in script

    ("(function cal_crc(pTrame){pTrame[0]=5;return pTrame[0];})");
   //same result
   QVariant(QVariantList, (QVariant(int, 48), QVariant(int, 49)))
    0 //not 5

if i return pTrame in script:

   "(function cal_crc(pTrame){pTrame[0]=5;return pTrame;})"
   qDebug() << m_fct_checksum.call(QScriptValue(),l_var).toVariant();
   QVariant(QVariantList, (QVariant(int, 48), QVariant(int, 49)))
    QVariant(int, 48)

or

 "function cal_crc(pTrame){return pTrame})"
  QVariant(QVariantList, (QVariant(int, 48), QVariant(int, 49)))
  QVariant(int, 48)
//return only the first,, it's strange because en i work in arg but not in return and can't modify i repeat..

any idea?

thanks

kickoune103

if i register pTrame is ok and not use in arg
//with this script: "(function(){pTrame[0]=5;return pTrame})"

QScriptValue l_var = m_engine.newArray(2);
l_var.setProperty( 0,QScriptValue('0') );
l_var.setProperty( 1,QScriptValue('1') );
m_engine.globalObject().setProperty("pTrame", l_var);

//console
QVariant(QVariantList, (QVariant(int, 48), QVariant(int, 49)))
QVariant(QVariantList, (QVariant(int, 5), QVariant(int, 49)))

any idea to do better?

Gojir4

@kickoune103 What do you mean by "if I register pTrame" ?

This is not clear for me when your C++ code is called, is it when crc_calc is called ?

It may be ambiguous to use the same name for your global property and the function's argument.
-> m_engine.globalObject().setProperty("pTrame", l_var);
-> function cal_crc(pTrame){return pTrame})

I suggest that you change the name of the arg:
-> function cal_crc(trame){trame[0]=5;return trame})