QJsonArray to Byte Array

Kris Revi

Qt Side of things

void Gradient::packGradient()
{
    // Always clear the QJsonArray befor resetting it!
    m_PaletteArray = QJsonArray();

    // Loop the _gradient and insert each point into the QJsonArray
    for (const auto &point : qAsConst(_gradient))
    {
        m_PaletteArray << round(point.stop * 255) << point.color.red() << point.color.green() << point.color.blue();
    }
}

This outputs

QJsonArray([0,255,255,255,116,0,0,0,255,0,0,0])

Then i send this via socket like this to the microcontroller ESP32

socket.sendCommandStrip(QString("colorGradient"), ui->L_GradientDisplay->getGradient());

ESP32 Microcontroller side of things
Header file

    private:
        // Gradient Color
        byte m_Gradient[256] = { 0,0,0,0,255,0,0,0 };

    public:
        void setGradient(byte gradientIn[256]);

Cpp File

void StripSettings::setGradient(byte gradientIn[])
{
    for (int i= 0; i < 256; i++) {
        m_Gradient[i]= gradientIn[i];
    }
}

MySocket.cpp

    if (doc["colorGradient"])
    {
        JsonArray array = doc["colorGradient"].as<JsonArray>();
        for(JsonVariant v : array) {
            Serial.println(v.as<int>()); 
        }

        //Strips[m_selectedStrip]->setGradient();
    }

How can i put the doc["colorGradient"] array into m_Gradient[256] this array?

sierdzio

Loop through the JSON array and put each value at different index of your C++ array.

Kris Revi

@sierdzio so basicaly like i did in the class setter?

void StripSettings::setGradient(byte gradientIn[])
{
    for (int i= 0; i < 256; i++) {
        m_Gradient[i]= gradientIn[i];
    }
}

but how do i get it into the setter function?

    if (doc["colorGradient"])
    {
        JsonArray array = doc["colorGradient"].as<JsonArray>();
        for(JsonVariant v : array) {
            Serial.println(v.as<int>()); 
        }

        //Strips[m_selectedStrip]->setGradient(); <--------------------- This
    }

I can't do this

        JsonArray array = doc["colorGradient"].as<JsonArray>();
        for(JsonVariant v : array) {
            Serial.println(v.as<int>());
           Strips[m_selectedStrip]->setGradient(v.as<int>());  // <------------ this is invalid
        }

Kris Revi

UPDATE

i did this to my ESP32 side but im still missing some stuff!

Header file

        // Gradient Color
        byte m_Gradient[256] = { 0,0,0,0,255,0,0,0 };
        // My Palette
        CRGBPalette32 m_myPal = m_Gradient;

    public:
        void setGradient(JsonArray array);

CPP file

void StripSettings::setGradient(JsonArray array)
{
    int i = 0;
    memset(m_Gradient, 0, sizeof(m_Gradient));
    for(JsonVariant v : array)
    {
        if (i >= 32) break;
            auto x = v.as<byte>();
            m_Gradient[i++] = x;
            Serial.print(x);
    }
}

This gives me

0000255000

but im missing the commas! how to add them?

Christian Ehrlicher

@Kris-Revi said in QJsonArray to Byte Array:

how to add them?

Maybe by Serial.print(',') ?

Kris Revi

@Christian-Ehrlicher said in QJsonArray to Byte Array:

@Kris-Revi said in QJsonArray to Byte Array:

how to add them?

Maybe by Serial.print(',') ?

i dont need the comma in the Serial.print but in the actual byte array (like i've done in the header file)

sierdzio

@Kris-Revi said in QJsonArray to Byte Array:

i dont need the comma in the Serial.print but in the actual byte array (like i've done in the header file)

An array is a row of values, with nothing in between. In your header file, when you write byte m_Gradient[256] = { 0,0,0,0,255,0,0,0 }; this sets the array (in computer memory) to 0000255000 value (but in binary, of course).

If you want to "pretty print it", do what @Christian-Ehrlicher recommended.