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

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  1. 3rd February 2013, 19:37 #1
    Momergil
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    Default Re: How to change a QwtPlotCurve color and thickness during the curve?

    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:

    Qt Code: 
    1. QVector<QPointF> samples;
    2.         samples.reserve( vetor_ativos[stock].periodicity[period].size() );
    3.  
    4.         for (int aaa = 0; aaa < vetor_ativos[stock].periodicity[period].size(); aaa++)
    5.         {
    6.             if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.probability == 0.0f)
    7.                 continue;
    8.  
    9.             samples += QPointF(QwtDate::toDouble(vetor_ativos[stock].periodicity[period][aaa].date),
    10.                                (double)vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.probability);
    11.         }
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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:

    Qt Code: 
    1. QPen up_normal(Qt::green,1.0);
    2.             QPen up_continuation(Qt::green,2.0);
    3.             QPen up_reversal(Qt::green,3.0);
    4.  
    5.             QPen down_normal(Qt::red,1.0);
    6.             QPen down_continuation(Qt::red,2.0);
    7.             QPen down_reversal(Qt::red,3.0);
    8.  
    9.             QPainter painter;
    10.  
    11. for (int aaa = 0; aaa < samples.size(); aaa++)
    12.             {
    13.                 if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.foward_direction == DIRECTION_POSITIVE)
    14.                 {
    15.                     if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
    16.                     {
    17.                         painter.setPen(up_continuation);
    18.  
    19.                     }
    20.                     else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
    21.                     {
    22.  
    23.                     }
    24.                     else
    25.                     {
    26.  
    27.                     }
    28.                 }
    29.                 else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.foward_direction == DIRECTION_NEGATIVE)
    30.                 {
    31.                     if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
    32.                     {
    33.  
    34.                     }
    35.                     else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
    36.                     {
    37.  
    38.                     }
    39.                     else
    40.                     {
    41.  
    42.                     }
    43.                 }
    44.                 else
    45.                 {
    46.                     if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_CONTINUATION)
    47.                     {
    48.  
    49.                     }
    50.                     else if (vetor_ativos[stock].periodicity[period][aaa].candle_probability_status.style == CAN_STYLE_REVERSION)
    51.                     {
    52.  
    53.                     }
    54.                     else
    55.                     {
    56.  
    57.                     }
    58.                 }
    59.             }
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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?
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  2. 4th February 2013, 00:34 #2
    Momergil
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    Default Re: How to change a QwtPlotCurve color and thickness during the curve?

    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:

    Qt Code: 
    1. void QwtPlotCurveSpecial::setPenVector(QVector<QPen> &vec)
    2. {
    3.     v_pen = vec;
    4. }
    5.  
    6. void QwtPlotCurveSpecial::drawLines(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
    7. {
    8.     if (from < v_pen.size())
    9.         p->setPen(v_pen[from]);
    10.  
    11.     QwtPlotCurve::drawLines(p,xMap,yMap,canvasRect,from,to);
    12. }
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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.
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  3. 5th February 2013, 01:10 #3
    Momergil
    Momergil is offline Advanced user
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    Default Re: How to change a QwtPlotCurve color and thickness during the curve?

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

    Qt Code: 
    1. void QwtPlotCurveSpecial::setPenVector(QVector<QPen> &vec)
    2. {
    3.     v_pen = vec;
    4. }
    5.  
    6. void QwtPlotCurveSpecial::drawLines(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
    7. {
    8.     for (int counter = 1; counter < v_pen.size(); counter++)
    9.     {
    10.         if (counter < v_pen.size())
    11.             p->setPen(v_pen[counter]);
    12.  
    13.         QwtPlotCurve::drawLines(p,xMap,yMap,canvasRect,counter-1,counter);
    14.     }
    15. }
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    Have a good use!

    Momergil
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