QwtPlot legend with axis

[desantossierra]

Hello,

I'm writing a Qt code using Qwt to represent some signals like in a EEG
I want do something like in this link

Now I represent the signals one above the other but I need represent a kind of legend with the voltage scale (like in the last link)

Any idea?

are there a qwt widget that I can use to do that?

Thanks in advance

[Uwe]

What about modifying the tick labels of the left scale ?

Use QwtPlot::setAxisScaleDiv to have major ticks at the positions, where you want to have your labels. Next derive from QwtScaleDraw and reimplement QwtScaleDraw::label() to return the special strings.

Uwe

[desantossierra]

I modified the left scale to write the names of each wave,
What I'd like to do is the floating legend with the microvolts and time scale,
maybe adding a widget that I can move through the QwtPlot dragging it or clicking in the graph.

thank you

[desantossierra]

I think I found a solution:

class QwtPlotWithScale: public QwtPlot
{
void drawCanvas(QPainter *p)
{
this->QwtPlot::drawCanvas(p);
p->save();
p->setPen(Qt::blue);
double x = this->transform(QwtPlot::xBottom,50);
double y = this->transform(QwtPlot::yLeft,0.5);
double xx = this->transform(QwtPlot::xBottom,75);
double yy = this->transform(QwtPlot::yLeft,1);
p->drawRect(x,y,xx-x,yy-y);
p->restore();
}
};

that is not the final solution but is the first approximation,
thank you
and kind regards

[Uwe]

I think I found a solution:

But not a good one - your code will be on screen only, not when using QwtPlotRenderer to generate documents.

You can do the same in QwtPlotWithScale::drawItems instead - or even better implement a small QwtPlotItem where you render your legend.
Check the examples - there are several simple plot items implemented.

Uwe

[desantossierra]

uops

Ok,
thank you, I'll try the last one with QwtPlotItem.