Nested class in Qt5

[jsulm]

@Juancinho_cardecan said in Nested class in Qt5:

I'm doing nested class for easy access to the variable brightValue inside a different class

This is really not a reason to use nested classes. You should think about clean design instead. Why not use getter/setter to access private fields?

[Juancinho_cardecan]

@mrjj Hi

I've been tried to implement your recommendation and also with setters/getters but at time that I want to pass the brightValue from the function void brightness::brightnessText(const QString &in) into the function void rgbLed::rgbRecive(const QString &in) unfortunately the variable b takes a random value inside the method rgbRecive:

This is the following code:

class rgbLed;

class brightness : public QObject
{
    Q_OBJECT
public:
    explicit brightness(QObject *parent = 0);
    friend rgbLed;
    void setBrightValue(int newbrightValueMember)
    {
        brightValueMember = newbrightValueMember;
    };
    int getBrightValue()
    {
        return brightValueMember;
    }

    bool flag = 0;
    int brightValueMember;

public slots:
    void brightnessText(const QString& in);
};

class rgbLed : public QObject
{
    Q_OBJECT
    Q_PROPERTY(int bright READ brigfht WRITE setBright NOTIFY brightChanged)
public:
    explicit rgbLed(QObject *parent = nullptr);
    brightness obj;
    int regresion_red(int red);
    int regresion_green(int green);
    int regresion_blue(int blue);

    Q_INVOKABLE int bright();
    Q_INVOKABLE int setBright(int x);
    Q_INVOKABLE void add(rgbLed *x);


    int r;
    int g;
    int b;
    int r2;
    int g2;
    int b2;
    int brightValue;
    int myBrightness;
    QStringList list;
    QString my_in;

    int red = 0;
    int green = 0;
    int blue = 0;
    int pos = 0 ;
    bool flag = 0;
    int x;

signals:
    void brightChanged(int x);

public slots:
    void rgbRecive(const QString &in);
};

and in my .cpp:

void brightness::brightnessText(const QString &in)
{

    QString Bright = in;
    int brightValue;
    brightValue = Bright.toInt(&flag);
    setBrightValue(brightValue);

    qDebug() << "bright: " << brightValue;
}

void rgbLed::rgbRecive(const QString &in)
{
    qDebug() << "ColorPicked:" << in;

    QStringList listNew = in.split(",");
    QStringList a_list = listNew[0].split("(");
    QStringList b_list = listNew[2].split(")");

    int b = obj.getBrightValue();
    qDebug() << "Value: " << b;
}

Could anyone see why b is taken a random value?

[jsulm]

@Juancinho_cardecan Where do you call brightness::brightnessText?
Do you call it on rgbLed::obj or maybe on another brightness instance?

[Juancinho_cardecan]

@jsulm I called here after your words but the value doesn't change:

void rgbLed::rgbRecive(const QString &in)
{
qDebug() << "ColorPicked:" << in;

QStringList listNew = in.split(",");
QStringList a_list = listNew[0].split("(");
QStringList b_list = listNew[2].split(")");

obj.brightnessText(in);
int b = obj.getBrightValue();
qDebug() << "Value: " << b;

}

[jsulm]

@Juancinho_cardecan Called where? And did you call it on rgbLed::obj?

[Juancinho_cardecan]

This post is deleted!

[Juancinho_cardecan]

@jsulm No I din't call it on rgbLed::obj, I called it inside the function void rgbLed::rgbRecive

[mrjj]

Hi
So here

void rgbLed::rgbRecive(const QString &in)
{
obj.brightnessText(in);
int b = obj.getBrightValue();

b is not what you expect ?

[Juancinho_cardecan]

@mrjj yes it's not what I'm expecting, it might be changing all the time but the value is zero always.

[mrjj]

@Juancinho_cardecan
I would check

brightValue = Bright.toInt(&flag);
(in void brightness::brightnessText(const QString &in))
and see if flag is false as that mean text to Int failed.

[Juancinho_cardecan]

@mrjj the flag is true and the value of brightValue is passing correctly, then the text to Int didn't failed, i dont know what is happening because if the values from QML are passing correctly, I'm calling in the wrong way the function brightnessText inside:

cpp file:

void rgbLed::rgbRecive(const QString &in)
{
     my_brightness.brightnessText(in);
    int b = my_brightness.getBrightValue();
    qDebug() << "Value: " << b;
}

void brightness::brightnessText(const QString &in)
{
    QString Bright = in;
    int brightValue;
    brightValue = Bright.toInt(&flag);
    qDebug() << "brightValue: " << brightValue;
    qDebug() << "flag: " << flag;
    setBrightValue(brightValue);

    qDebug() << "bright: " << brightValue;
}

main.cpp:

int main(int argc, char *argv[])
{

    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);
   

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
            return -1;

    //Root Object to find Items in QML
    QObject* root = engine.rootObjects()[0];
    assert(root != nullptr);

    // The QML Item to which we want to inject our QML-Item-loaded-from-file
    QQuickItem* colorSelector = qobject_cast<QQuickItem*>(root->findChild<QObject*>("colorSelector"));
    assert(colorSelector != nullptr);


    // Load the QML file to a component
    QString qml_path = "ColorSelector.qml";
    QQmlComponent comp(&engine, QUrl::fromLocalFile(qml_path));

    QScopedPointer<rgbLed> slider (new rgbLed);
    engine.rootContext()->setContextProperty("slider", slider.data());
    QObject *topLevel = engine.rootObjects().value(0);
    QQuickWindow *window = qobject_cast<QQuickWindow *>(topLevel);

    // Create an instance of the component
    rgbLed my_rgbLed;//Creation an Object instance
    brightness my_brightness;

    //Code to conecct a signal with the slot
    QObject::connect(colorSelector, SIGNAL(colorChanged(QString)), &my_rgbLed, SLOT(rgbRecive(QString)));

    // connect our QML signal to our C++ slot
      QObject::connect(window, SIGNAL(submitTextField(QString)), &my_brightness, SLOT(brightnessText(QString)));

    return app.exec();
}

header file:

class rgbLed;

class brightness : public QObject
{
    Q_OBJECT
public:
    explicit brightness(QObject *parent = 0);
    friend rgbLed;
    void setBrightValue(int newbrightValueMember)
    {
        brightValueMember = newbrightValueMember;
    };
    int getBrightValue()
    {
        return brightValueMember;
    }

    bool flag = 0;
    int brightValueMember;

public slots:
    void brightnessText(const QString& in);
};


class rgbLed : public QObject
{
    Q_OBJECT
    Q_PROPERTY(int bright READ brigfht WRITE setBright NOTIFY brightChanged)
public:
    explicit rgbLed(QObject *parent = nullptr);
    brightness my_brightness;
    int regresion_red(int red);
    int regresion_green(int green);
    int regresion_blue(int blue);

    Q_INVOKABLE int bright();
    Q_INVOKABLE int setBright(int x);
    Q_INVOKABLE void add(rgbLed *x);


    int r;
    int g;
    int b;
    int r2;
    int g2;
    int b2;
    int brightValue;
    int myBrightness;
    QStringList list;
    QString my_in;

    int red = 0;
    int green = 0;
    int blue = 0;
    int pos = 0 ;
    bool flag = 0;
    int x;

signals:
    void brightChanged(int x);

public slots:
    void rgbRecive(const QString &in);
}

[mrjj]

Hi
I think you have 2 instances of brightness called my_brightness

void rgbLed::rgbRecive(const QString &in)
{
my_brightness.brightnessText(in); <<< is the SAME my_brightness as you have in main.cpp?
int b = my_brightness.getBrightValue();
qDebug() << "Value: " << b;
}

so
rgbLed my_rgbLed;//Creation an Object instance
brightness my_brightness;

how does the my_brightness from outside come into

void rgbLed::rgbRecive(const QString &in) ?
It seems it has its own ?
So one is being updated but other is not ?

In the original code, it was called

class rgbLed : public QObject
{
    Q_OBJECT
    Q_PROPERTY(int bright READ brigfht WRITE setBright NOTIFY brightChanged)
public:
    explicit rgbLed(QObject *parent = nullptr);
    brightness obj; <<< the old internal name of the instance

So it works from QML
as you do
// connect our QML signal to our C++ slot
QObject::connect(window, SIGNAL(submitTextField(QString)), &my_brightness, SLOT(brightnessText(QString)));

and that changes the one in Mian.cpp
but the rgbLed my_rgbLed; and its "obj" is not.

I assume you want the brigness instance inside my_rgbLed to change ?

[jsulm]

@mrjj said in Nested class in Qt5:

I think you have 2 instances of brightness called my_brightness

I already tryied to explain that...

[JonB]

@Juancinho_cardecan
Assuming @jsulm & @mrjj are correct, each time you create a brightness object anywhere why don't you set its https://doc.qt.io/qt-5/qobject.html#objectName-prop (setObjectName()) to a unique string, then you can see whether one instance is different from another. Printing out &brightnessObjectInstance may also tell you the same, I think.

[mrjj]

Hi

Could you try to add

brightness & rgbLed: :getBrightness() {
return obj; // or what you called it
}

to
class rgbLed : public QObject

then in main.cpp

QObject::connect(window, SIGNAL(submitTextField(QString)), my_rgbLed.getBrightness(), SLOT(brightnessText(QString)));

and remove all
brightness my_brightness;
as we dont want to use brightness alone ever, only via rgbLed.