QML continuous item update

Question

There is data that is updated at a constant speed, in addition there is an Image element that is shown, or disappears, depending on the data received.

In my case, Image receives data once and for all. When the program is running, changing the data Image does not respond.

How to make the data perceived element Image in real time?

 Image { id: indicator1 x: 320 y: 257 fillMode: Image.PreserveAspectFit source: "../images/grn.png" visible: stringList[0] === "0" || stringList[0] === "1" ? true : false }

In *.cpp

 void SerialPort::processSingleRecord (QByteArray value) { QString value2 = QString(value).trimmed(); QStringList sl = value2.split(","); QString qqq; std::vector<QString> fullData; fullData.reserve(sl.size()+22); for(int i = 0; i < sl.size()-1; i++) fullData.push_back(sl[i]); QString lastItem = sl[sl.size()-1]; for(int i = 0; i < lastItem.size(); i++) fullData.push_back(QString(lastItem[i])); for(int i = 0; i <fullData.size(); i++) qqq+= fullData[i]+','; set_serial_data(qqq); }

In *.qml

  SerialPort { id: cppClass } property variant stringList: cppClass.serial_data.split(',') Image { id: indicator1 x: 320 y: 257 fillMode: Image.PreserveAspectFit source: "../images/grn.png" visible: stringList[0] === "0" || stringList[0] === "1" ? true : false }

The ternary operator for visible is redundant, and in fact you need to change the visibility of the image where you get the corresponding data using the image component id indicator1
I get the data in the .cpp file, and in qml I'm already referring to the right element ....
In * .cpp, void SerialPort :: processSingleRecord (QByteArray value) {QString value2 = QString (value) .trimmed ();
for (int i = 0; i <sl.size () - 1; i ++) fullData.push_back (sl [i]);
for (int i = 0; i <lastItem.size (); i ++) fullData.push_back (QString (lastItem [i]));
for (int i = 0; i <fullData.size (); i ++) qqq + = fullData [i] + ',';
} In * .qml SerialPort {id: cppClass} property variant stringList: cppClass.serial_data.split (',')

Accepted Answer · 2018-12-27T11:06:42

And so, you have a class SerialPort , in the method of which processSingleRecord you process incoming data from some serial port. As a result of processing, you form a string list whose first element can be either 0 or 1 .

 // SerialPort.cpp class SerialPort { public: signals: void stateChanged(QString value); // Сигнализируем только о первом значении списка, что делать с остальными вы решите сами private slots: void processSingleRecord(QByteArray data) { //... emit stateChanged( fullData[0] ); } }

Register the SerialPort class in main.cpp , for example:

 //... qmlRegisterType<SerialPort>("ru.user321152", 1, 0, "SerialPort"); // ...

Go to main.qml .

 import ru.user321152.SerialPort 1.0 ApplicationWindow { Image { id: indicator1; } SerialPort { onStateChanged: { // обратите внимание на префикс on // value - строковое значение состояния indicator1.visible = value === "1" } } }

so, with one value, everything worked for me ... onStateChanged: {indicator1.visible = stringList [6] === "0"} and how do I now make it so that onStateChanged works like this: {indicator1.visible = stringList [ 6] === "0" indicator1.visible = stringList [7] === "1" indicator1.visible = stringList [8] === "0" indicator1.visible = stringList [9] === "1" }
I or someone else will try to answer, otherwise it’s not very convenient for me, because I still have to write code
But no, my version Works with your code ... everything is fine.
Tested while 3 lamps, each lit depending on the signal that comes.

QML continuous item update

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