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If I have a
signal:
void foo(QByteArray data);
And in QML I handle it:
onFoo: {
console.log(data.toString());
}
What is the type of data in QML? What methods does it have? It doesn't seem to be a javascript string - it doesn't even have a .length, and no .charCodeAt(). But it also doesn't seem to be a QByteArray - no .at(). data[0] is undefined! It does have .toString().
How do I access its contents? E.g. if it is a four-byte uint32_t, how do I get that number into a javascript variable?
323
QByteArray is the Qt class to store a array of bytes. It is analogous to a char *. Unlike a QString, a QByteArray has no encoding information and makes no attempt to decode bytes into characters.
One way to initialize a QByteArray is simply to pass a const char * to its constructor. For example, the following code creates a byte array of size 5 containing the data "Hello": QByteArray ba("Hello");
As stated in here :
The QML engine provides automatic type conversion between QByteArray values and JavaScript ArrayBuffer objects.
This feature is available since Qt 5.8.
162
According to http://doc.qt.io/qt-5/qtqml-cppintegration-data.html and the current source http://code.woboq.org/qt5/qtdeclarative/src/qml/compiler/qqmltypecompiler.cpp.html#567, there's no conversion between QByteArray towards QML. You'll probably get an opaque, unaccesible Object in JS.
EDIT: The above was true up to Qt 5.8. 5.8 added a conversion between QByteArray and JS Array, see the other answer.
Needless to say: at the time of this writing, the only version you want to be using is >= 5.12.
3
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