QwtScaleDraw is not update in realtime graph

[alizadeh91]

Hi,,
I've implemented QwtScaleDraw to make a realtime graph like qwt example(cpu usage example):

class TimeScaleDraw: public QwtScaleDraw
{
public:
    TimeScaleDraw(const QTime &base):
        baseTime(base)
    {
    }
    virtual QwtText label(double v) const
    {
        QTime upTime = baseTime.addMSecs((int)v);
        return upTime.toString();
    }
 
    QTime baseTime;
};

class TimeScaleDraw: public QwtScaleDraw
{
public:
    TimeScaleDraw(const QTime &base):
        baseTime(base)
    {
    }
    virtual QwtText label(double v) const
    {
        QTime upTime = baseTime.addMSecs((int)v);
        return upTime.toString();
    }

    QTime baseTime;
};

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I want to update baseTime to current time in every timer interval instead of adding to the array in every cycle.

i call setAxisScale(QwtPlot::yLeft,timeData[INTERVAL-1],timeData[0]) in every cycle but the timeData array is held to be fix (is 0 to 60 for 60 data to be plotted).)

Actually i want to my array(data of y axis) be fixed but baseTime will update in every cycle.
When i do that the labels are not changing. actually the label function is not calling because when i call setAxisScale in timer scale the scale seems to be constant but because the basetime is changing so it must update itself!!

How can i make this class to update itslef(call the label function whenever i call setAxisScale(QwtPlot::yLeft,timeData[INTERVAL-1],timeData[0]))( the timeData array is fix))

[Uwe]

See QwtAbstractScaleDraw::invalidateCache: http://qwt.sourceforge.net/class_qwt...05aa5295409aa6

Uwe

[alizadeh91]

Thanks Uwe, As i said i override it but the problem is when i want to send current time to its implemented class(QwtScaleDraw) and when my array for y axis is fix and is not changing the y-axis also is not changing and updating. But i don't understand how to do that?

Forget to say my graph is vertically so i said y-axis!!

---

Added after 5 minutes:

Uwe, What i want to do : I've add QwtPlotGrid to realtime example of qwt. And the girds will moving as time. i want to fix labels to don't move as time. So i want instead of incrementing the array in timer, send current time in timer and add it by a constant array.

[Uwe]

As i said i override it ...

What has nothing to do with my link about QwtAbstractScaleDraw::invalidateCache ...

class TimeScaleDraw: public QwtScaleDraw
{
public:
    ....
 
    void setBaseTime( const QTime &time )
    {
        m_baseTime = time;
        invalidateCache();
    }
 
    ....
private:
    QTime m_baseTime;
};

class TimeScaleDraw: public QwtScaleDraw
{
public:
    ....

    void setBaseTime( const QTime &time )
    {
        m_baseTime = time;
        invalidateCache();
    }

    ....
private:
    QTime m_baseTime;
};

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Then the next replot will update the tick labels.

Uwe

[alizadeh91]

You are my hero man

[alizadeh91]

I'm sorry uwe!! but it won't work!!! it's not rescalling the axis.??

[Uwe]

What it does is to return different labels for the same values depending on the base time - without rescaling.
When you want to rescale I didn't get what you want to do.

Uwe