for (int i = 0; i < offset; i++)

        {

            (*channelDataArray)[i] = (*channelDataArray)[i + shift];

        }

        // place new samples

        for (int i = 0; i < data.size(); i++)

        {

            (*channelDataArray)[offset + i] = data[i];

        }

    }

    // update plot

    curves[channel]->setSamples(dataX, (*channelDataArray));

    ui->plot->replot(); // TODO: replot after all channel data updated

}

void MainWindow::clearPlot()

{

    for (unsigned int ci = 0; ci < numOfChannels; ci++)

    {

        channelsData[ci].fill(0.0);

        curves[ci]->setSamples(dataX, channelsData[ci]);

    }

    // update plot

    ui->plot->replot();

}

void MainWindow::onNumOfSamplesChanged(int value)

{

    unsigned int oldNum = this->numOfSamples;

    numOfSamples = value;

    // resize data arrays

    if (numOfSamples < oldNum)

    {

        dataX.resize(numOfSamples);

        for (unsigned int ci = 0; ci < numOfChannels; ci++)

        {

            channelsData[ci].remove(0, oldNum - numOfSamples);

        }

    }

    else if(numOfSamples > oldNum)

    {

        dataX.resize(numOfSamples);

        for (unsigned int i = oldNum; i < numOfSamples; i++)

        {

            dataX[i] = i;

            for (unsigned int ci = 0; ci < numOfChannels; ci++)

            {

                channelsData[ci].prepend(0);

            }

        }

    }

}

void MainWindow::onNumOfChannelsChanged(int value)

{

    unsigned int oldNum = this->numOfChannels;

    this->numOfChannels = value;

    if (numOfChannels > oldNum)

    {

        // add new channels

        for (unsigned int i = 0; i < numOfChannels - oldNum; i++)

        {

            channelsData.append(DataArray(numOfSamples, 0.0));

            curves.append(new QwtPlotCurve());

            curves.last()->setSamples(dataX, channelsData.last());

            curves.last()->setPen(makeColor(curves.length()-1));

            curves.last()->attach(ui->plot);

        }

    }

    else if(numOfChannels < oldNum)

    {

        // remove channels

        for (unsigned int i = 0; i < oldNum - numOfChannels; i++)

        {

            channelsData.removeLast();

            auto curve = curves.takeLast();

            curve->detach();

            delete curve;

        }

    }

}

void MainWindow::onAutoScaleChecked(bool checked)

{

    if (checked)

    {

        ui->plot->setAxisAutoScale(QwtPlot::yLeft);

        ui->lYmin->setEnabled(false);

        ui->lYmax->setEnabled(false);

        ui->spYmin->setEnabled(false);

        ui->spYmax->setEnabled(false);

    }

    else

    {

        ui->lYmin->setEnabled(true);

        ui->lYmax->setEnabled(true);

        ui->spYmin->setEnabled(true);

        ui->spYmax->setEnabled(true);

        ui->plot->setAxisScale(QwtPlot::yLeft, ui->spYmin->value(),

                               ui->spYmax->value());

    }

}

void MainWindow::onYScaleChanged()

{

    ui->plot->setAxisScale(QwtPlot::yLeft, ui->spYmin->value(),

                           ui->spYmax->value());

}

void MainWindow::onNumberFormatButtonToggled(int numberFormatId, bool checked)

{

    if (checked) selectNumberFormat((NumberFormat) numberFormatId);

}

void MainWindow::selectNumberFormat(NumberFormat numberFormatId)

{

    numberFormat = numberFormatId;

    switch(numberFormat)

    {

        case NumberFormat_uint8:

            sampleSize = 1;

            readSample = &MainWindow::readSampleAs<quint8>;

            break;

        case NumberFormat_int8:

            sampleSize = 1;

            readSample = &MainWindow::readSampleAs<qint8>;

            break;

        case NumberFormat_uint16:

            sampleSize = 2;

            readSample = &MainWindow::readSampleAs<quint16>;

            break;

        case NumberFormat_int16:

            sampleSize = 2;

            readSample = &MainWindow::readSampleAs<qint16>;

            break;

        case NumberFormat_uint32:

            sampleSize = 4;

            readSample = &MainWindow::readSampleAs<quint32>;

            break;

        case NumberFormat_int32:

            sampleSize = 4;

            readSample = &MainWindow::readSampleAs<qint32>;

            break;

        case NumberFormat_float:

            sampleSize = 4;

            readSample = &MainWindow::readSampleAs<float>;

            break;

        case NumberFormat_ASCII:

            sampleSize = 0;    // these two members should not be used

            readSample = NULL; // in this mode

            break;

    }

    if (numberFormat == NumberFormat_ASCII)

    {

        QObject::disconnect(&(this->serialPort), &QSerialPort::readyRead, 0, 0);

        QObject::connect(&(this->serialPort), &QSerialPort::readyRead,

                         this, &MainWindow::onDataReadyASCII);

        portControl.enableSkipByte();

    }

    else

    {

        QObject::disconnect(&(this->serialPort), &QSerialPort::readyRead, 0, 0);

        QObject::connect(&(this->serialPort), &QSerialPort::readyRead,

                         this, &MainWindow::onDataReady);

        portControl.enableSkipByte(false);

    }

}

template<typename T> double MainWindow::readSampleAs()

{

    T data;

    this->serialPort.read((char*) &data, sizeof(data));

    return double(data);

}

bool MainWindow::isDemoRunning()

{

    return ui->actionDemoMode->isChecked();

}

void MainWindow::demoTimerTimeout()

{

    demoCount++;

    if (demoCount > 100) demoCount = 0;

    for (unsigned int ci = 0; ci < numOfChannels; ci++)

    {

        DataArray data(1);

        data.replace(0, (ci + 1)*demoCount);

        addChannelData(ci, data);

    }

}

void MainWindow::enableDemo(bool enabled)

{

    if (enabled)

    {

        if (!serialPort.isOpen())

        {

            demoTimer.start();

            ui->actionDemoMode->setChecked(true);

        }

        else

        {

            ui->actionDemoMode->setChecked(false);

        }

    }

    else

    {

        demoTimer.stop();

        ui->actionDemoMode->setChecked(false);

    }

}

/*

  Below crude drawing demostrates how color selection occurs for

  given channel index

  0°                     <--Hue Value-->                           360°

  |* . o . + . o . * . o . + . o . * . o . + . o . * . o . + . o . |

  * -> 0-3

  + -> 4-7

  o -> 8-15

  . -> 16-31

 */

QColor MainWindow::makeColor(unsigned int channelIndex)

{

    auto i = channelIndex;

    if (i < 4)

    {

        return QColor::fromHsv(360*i/4, 255, 230);

    }

    else

    {

        double p = floor(log2(i));

        double n = pow(2, p);

        i = i - n;

        return QColor::fromHsv(360*i/n + 360/pow(2,p+1), 255, 230);

    }

}