{+details}: simple button to plot a point, but my slots have no effect on the plot (QwtPlot)

[S. A. <sa...@ya...>]

I'm adding more details to the email, cause some of it was dropped earlier .


Sorry, like I said I am new to Qwt, but his is a  qwt issue since
it is a plot that i am working with.  Let me expand, part of the
original email
was not included:

The problems are:

1. code in a (public) slot, does not work on the QwtPlot, but if called from the main loop ( or constructor) it works fine.
mywidget::mywidget(QWidget *parent): 
QWidget(parent)
{
      QwtPlot *myplot = new QwtPlot;
      button = new QPushButton("plot");
   
       // omitting code to put it in a layout 
connect( button, SIGNAL( clicked() ), myplot, SLOT( myslot() ));
}
void mywidget::myslot(void)
{
    printf(" myslot() \n");

     // code to add data to the plot
     // does not work
     curve1->setData( x, y, points)
      curve1->attach(myplot);
     myplot->replot();

}

When I hit the button, it only prints the printf statement, but does not plot anything.
If I take that code and put it in the constructor, then the  curve is plotted.

2. code for changing the x-axis scale from Linear to LogScale works only on Mac OS and not in Linux.
    I've searched for a solution, but have not been lucky.


  


________________________________
From: Rainer Thaden <RT...@we...>
To: S. Aguinaga <sa...@ya...>; List for both Qwt users and developers <qwt...@li...>
Sent: Mon, November 16, 2009 10:10:06 AM
Subject: Re: simple button to plot a point, but my slots have no effect   on the plot (QwtPlot)


> I do have the Q_OBJECT macro called from the header file, I just omitted some of the code.
> 
> Because  the code that adds the 'curve' and the 'marker or symbol' to the plot do not work
> when called from the slot, I think it's a QWT question.  I also ran into a problem with the
> axis scale (from linear to logscale), it works in the main part of the loop, but if I try changing
> it from a slot, it doesn't work on Linux, but works fine in Mac OS (same code!).
> 
> I even tried making the slot public, and that doesn't work either.
> I've tried with with qwt 5.1 and 5.2 versions and in Linux, I get the same behavior.
> 

Are
you sure, that your slot gets called at all? Did you try to add a
qDebug there to write something to the console when the slot get's
called?

> 
> I'm trying to create a different class with a built-in slot to do this plotting and call it in my code as:  My_Plot *plot = new My_Plot (this);
> instead of the way I am doing it now, which is:
>                 QwtPlot *plot = new QwtPlot;
> 
> again, any help or code samples that could get me get over the hump on this
> will be appreciated.
> 

What's your question? How to derive a class?

class PlotWidget: public QwtPlot
{
   Q_OBJECT
public:
   PlotWidget(QWidget *parent=0);

public Q_SLOTS:
   void mySlot(int myParam);
};

That's basic C++ / Qt knowledge and I am afraid this is not the right group for that.

Regards,

Rainer

> Thank you fellows.
> 
> // Sal // Northwestern University


________________________________
From: S. Aguinaga <sa...@ya...>
To: Martin Gebert <mar...@al...>; List for both Qwt users and developers <qwt...@li...>
Sent: Mon, November 16, 2009 9:40:51 AM
Subject: Re: simple button to plot a point,   but my slots have no effect   on the plot (QwtPlot)


Thanks Martin.

I do have the Q_OBJECT macro called from the header file, I just omitted some of the code.

Because  the code that adds the 'curve' and the 'marker or symbol' to the plot do not work
when called from the slot, I think it's a QWT question.  I also ran into a problem with the
axis scale (from linear to logscale), it works in the main part of the loop, but if I try changing
it from a slot, it doesn't work on Linux, but works fine in Mac OS (same code!).

I even tried making the slot public, and that doesn't work either.
I've tried with with qwt 5.1 and 5.2 versions and in Linux, I get the same behavior.

I'm still new to Qwt and Qt, so any help you can provide will be greatly appreciated.

I'm trying to create a different class with a built-in slot to do this plotting and call it in my 
code as:  My_Plot *plot = new My_Plot (this);
instead of the way I am doing it now, which is:
                QwtPlot *plot = new QwtPlot;

again, any help or code samples that could get me get over the hump on this
will be appreciated.

Thank you fellows.

// Sal 
// Northwestern University


________________________________
From: Martin Gebert <mar...@al...>
To: S. Aguinaga <sa...@ya...>; List for both Qwt users and developers <qwt...@li...>
Sent: Mon, November 16, 2009 2:27:42 AM
Subject: Re: simple button to plot a point,   but my slots have no effect   on the plot (QwtPlot)

This is a general Qt question and not specific to Qwt. However,


> harpWestWidget::harpWestWidget()

is this class a QObject, and did you insert the Q_OBJECT macro in its
declaration? What does the console say when you call the app and
connect() is called?

Martin