real time graph plot

[robotics]

hi Every body I want to plot real time 2D graph
example some value in y-axis and some value in Y-axis
How to do this
please help
Every help shall be appreciated

[robotics]

Ok I managed to download the QWT library and build it
can someone provide simple example just ...a simple plot that indicate that my I am able to plot ....
please someone might have done this..

[Kangs]

There are several examples with Qwt. For your needs, check cpuplot and oscilloscope.

[robotics]

I tried the examples but they are not helping me
can u suggest any one of the classes that I can start with

[Kangs]

Why these examples do not help you ?
cpuplot is very simple, try to modify it for your needs,
it's just 4 curves updated with a timer.

[vangaurd]

Hi..All you need to do is re-implement widgets paintevent() with your real time data. Mostly you may need to use drawLine() function of QPainter.
sample logic:

QList<QPair<double,double> > realData; //initialize with ur data
void paintEvent(QPaintEvent *)
{
   QPainter painter(this);
   painter.setPen(QPen(QColor(200,100,0)));
   for(int i=0; i<realData.count()-1; i++)
   {
      painter.drawLine(QPointF(realData.at(i).first,realData.at(i).second),QPointF(realData.at(i+1).first,realData.at(i+1).second));
   }
}

QList<QPair<double,double> > realData; //initialize with ur data
void paintEvent(QPaintEvent *)
{
   QPainter painter(this);
   painter.setPen(QPen(QColor(200,100,0)));
   for(int i=0; i<realData.count()-1; i++)
   {
      painter.drawLine(QPointF(realData.at(i).first,realData.at(i).second),QPointF(realData.at(i+1).first,realData.at(i+1).second));
   }
}

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You can check the sample codes and qt documentation for custom painting.