How to change a QwtPlotCurve color and thickness during the curve?

[Uwe]

You have to overload QwtPlotCurve::drawLines().

Uwe

[Momergil]

You have to overload QwtPlotCurve::drawLines().

Uwe

Hmm I see. But how exactly should I do this? I mean, must I overload the function in the original qwt 6.1 files and than recompile and reinstall it?

Besides, wouldn't it be better/simpler to create another class that inherits QwtPlotCurve and than create this new drawLines() on it?

Any other tip?

[Uwe]

Besides, wouldn't it be better/simpler to create another class that inherits QwtPlotCurve and than create this new drawLines() on it?

This is exactly how to "overload" a virtual method !

Uwe

[Momergil]

This is exactly how to "overload" a virtual method !

Uwe

Hmmm ok I'll see what I can do than I return with the results.

[jesse_mark]

did you got any new result, man ??

I am interested to see/know how you did that?? its

[Momergil]

did you got any new result, man ??

I am interested to see/know how you did that?? its

Oh, actually not. While I need some day to do this, I wasn't in a hurry to do it; it's not a priority in my software :P

But since there is someonelse interested on it, i'll concentrate myself on this as soon as possible

[Momergil]

So, after some investigation...

I found out that I have no idea whatsoever about how to do this ^^

Problems I found:

the differentiantion in thickness and color is not relative to the y or x value of the curve; rather it's based on uchar values outisde the implementation of the curve (it's a vector that hold the Y points and the uchar values, so I copied the Y data to a new QPointF values and that I put inside the curve:

QVector<QPointF> samples;
        samples.reserve( vetor_ativos[stock].periodicity[period].size() );
 
        for (int aaa = 0; aaa < vetor_ativos[stock].periodicity[period].size(); aaa++)
        {
            if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.probability == 0.0f)
                continue;
 
            samples += QPointF(QwtDate::toDouble(vetor_ativos[stock].periodicity[period][aaa].date),
                               (double)vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.probability);
        }

QVector<QPointF> samples;
        samples.reserve( vetor_ativos[stock].periodicity[period].size() );

        for (int aaa = 0; aaa < vetor_ativos[stock].periodicity[period].size(); aaa++)
        {
            if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.probability == 0.0f)
                continue;

            samples += QPointF(QwtDate::toDouble(vetor_ativos[stock].periodicity[period][aaa].date),
                               (double)vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.probability);
        }

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My ideia would be about doing a for(; that would catch the data type and depending on the results, change the curve style:

QPen up_normal(Qt::green,1.0);
            QPen up_continuation(Qt::green,2.0);
            QPen up_reversal(Qt::green,3.0);
 
            QPen down_normal(Qt::red,1.0);
            QPen down_continuation(Qt::red,2.0);
            QPen down_reversal(Qt::red,3.0);
 
            QPainter painter;
 
for (int aaa = 0; aaa < samples.size(); aaa++)
            {
                if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.foward_direction == DIRECTION_POSITIVE)
                {
                    if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
                    {
                        painter.setPen(up_continuation);
 
                    }
                    else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
                    {
 
                    }
                    else
                    {
 
                    }
                }
                else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.foward_direction == DIRECTION_NEGATIVE)
                {
                    if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
                    {
 
                    }
                    else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
                    {
 
                    }
                    else
                    {
 
                    }
                }
                else
                {
                    if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
                    {
 
                    }
                    else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
                    {
 
                    }
                    else
                    {
 
                    }
                }
            }

QPen up_normal(Qt::green,1.0);
            QPen up_continuation(Qt::green,2.0);
            QPen up_reversal(Qt::green,3.0);

            QPen down_normal(Qt::red,1.0);
            QPen down_continuation(Qt::red,2.0);
            QPen down_reversal(Qt::red,3.0);

            QPainter painter;

for (int aaa = 0; aaa < samples.size(); aaa++)
            {
                if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.foward_direction == DIRECTION_POSITIVE)
                {
                    if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
                    {
                        painter.setPen(up_continuation);

                    }
                    else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
                    {

                    }
                    else
                    {

                    }
                }
                else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.foward_direction == DIRECTION_NEGATIVE)
                {
                    if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
                    {

                    }
                    else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
                    {

                    }
                    else
                    {

                    }
                }
                else
                {
                    if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
                    {

                    }
                    else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
                    {

                    }
                    else
                    {

                    }
                }
            }

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But simply overloading drawLines(...) don't seems to have any good, once I have no way of exctracting the parameters values to use the function. Does somebody have any idea? Any other way of how to do this?

[Momergil]

Ok, I guess I found a solution while I was taking a bath :P

This are the different parts of my new class that inherits QwtPlotCurve:

void QwtPlotCurveSpecial::setPenVector(QVector<QPen> &vec)
{
    v_pen = vec;
}
 
void QwtPlotCurveSpecial::drawLines(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
{
    if (from < v_pen.size())
        p->setPen(v_pen[from]);
 
    QwtPlotCurve::drawLines(p,xMap,yMap,canvasRect,from,to);
}

void QwtPlotCurveSpecial::setPenVector(QVector<QPen> &vec)
{
    v_pen = vec;
}

void QwtPlotCurveSpecial::drawLines(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
{
    if (from < v_pen.size())
        p->setPen(v_pen[from]);

    QwtPlotCurve::drawLines(p,xMap,yMap,canvasRect,from,to);
}

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As you may see, I calibrate a QVector<QPen> vector to hold the QPen appropriate for each draw of the curve. I'm not sure actually if it works because the base algorithm to use this implementation is not ready, but you may use it for personal tests.

[Momergil]

Ok, the above code actually don't work... Here is the final version:

void QwtPlotCurveSpecial::setPenVector(QVector<QPen> &vec)
{
    v_pen = vec;
}
 
void QwtPlotCurveSpecial::drawLines(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
{
    for (int counter = 1; counter < v_pen.size(); counter++)
    {
        if (counter < v_pen.size())
            p->setPen(v_pen[counter]);
 
        QwtPlotCurve::drawLines(p,xMap,yMap,canvasRect,counter-1,counter);
    }
}

void QwtPlotCurveSpecial::setPenVector(QVector<QPen> &vec)
{
    v_pen = vec;
}

void QwtPlotCurveSpecial::drawLines(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
{
    for (int counter = 1; counter < v_pen.size(); counter++)
    {
        if (counter < v_pen.size())
            p->setPen(v_pen[counter]);

        QwtPlotCurve::drawLines(p,xMap,yMap,canvasRect,counter-1,counter);
    }
}

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Have a good use!

Momergil