qwt mouseEvents

[halberdier83]

Hi all,

I have a QwtPlot in my form. And i want to put a vertical line marker when the user right mouse button clicks onto the canvas of the qwtPlot. I have no problem to set markers, but i need to get mouse click events of qwtPlot. I found the setMousePattern in QwtPlotPicker class. I used it, but nothing changed.

I wonder if QwtPlot has rightButtonClicked signal. or is there anyother way to do this?

[ToddAtWSU]

I haven't worked with qwt before, but do they have a mousePressEvent or mouseReleaseEvent anywhere? If you capture these events, then you can use the function, I believe it is event->button( ) or event->buttons( ) to figure out what buttons the user is pressing. If the button is right, then add your code to add your marker line. Hopefully this will help you.

[halberdier83]

I haven't worked with qwt before, but do they have a mousePressEvent or mouseReleaseEvent anywhere? If you capture these events, then you can use the function, I believe it is event->button( ) or event->buttons( ) to figure out what buttons the user is pressing. If the button is right, then add your code to add your marker line. Hopefully this will help you.

I am sorry but these classes have no signals like that. That is what i am actually asking. in qt3, i made some applications using QMouseEvent, QKeyEvent. But i realised that there is a different approach to these events in qwt. There are QwtPickerMachine, QwtEventPattern classes. But, i found no code examples so i dont know how to implement them. I also dont know whether they are what i am looking for or not. But thanks anyway for your interest.

[ToddAtWSU]

Aren't qwt objects objects based off different Qt objects? If so, all QWidgets have mousePressEvent and mouseReleaseEvent as far as I know. Maybe you could subclass one of these qwt classes and add in the mouse event(s) you want? Just an idea...sorry it's not a better answer.

[Uwe]

QwtPlot is a composite widget - for catching mouse events on its canvas you need to install an event filter for plot->canvas().
That's exactly what QwtPlotPicker does - guess this is the class, what you are looking for.

Uwe

[halberdier83]

QwtPlot is a composite widget - for catching mouse events on its canvas you need to install an event filter for plot->canvas().
That's exactly what QwtPlotPicker does - guess this is the class, what you are looking for.

Uwe

Hi Uwe,

I also need some sample code. QWT documentation is not enough for me. Can you provide me a sample code for this?

[Uwe]

I'm not sure what you want to implement, but the code below displays a vertical line, while you are pressing the right mouse button on the canvas:

QwtPlotPicker *picker = new QwtPlotPicker(plot->canvas());
picker->setSelectionFlags(QwtPicker::PointSelection | QwtPicker::DragSelection);
picker->setRubberBandPen(QColor(Qt::red));
picker->setRubberBand(QwtPicker::VLineRubberBand);
picker->setMousePattern(QwtPicker::MouseSelect1, Qt::RightButton);

QwtPlotPicker *picker = new QwtPlotPicker(plot->canvas());
picker->setSelectionFlags(QwtPicker::PointSelection | QwtPicker::DragSelection);
picker->setRubberBandPen(QColor(Qt::red));
picker->setRubberBand(QwtPicker::VLineRubberBand);
picker->setMousePattern(QwtPicker::MouseSelect1, Qt::RightButton);

To copy to clipboard, switch view to plain text mode 

If you want to add a permanent line, I would use a picker without rubberband and QwtPlotPicker::ClickSelection. Then all you need to do is to connect a slot to the QwtPlotPicker::selected signal ( you get a polygon with one point), where you attach a line marker.

HTH,
Uwe

[pospiech]

I have trouble with mouseEvents as well.
I want to send the values the Tracker displays as an Signal when the plot is clicked at that point.

I tried the following

void QSpectrogramPlot::initWidget()
{
	delete m_picker;
	m_picker = new QwtPicker(this);
	connect(m_picker, SIGNAL(selected(const QwtPolygon &)), this, SLOT(OnPickerPointSelected(const QwtPolygon &)));
 
	// emit the position of clicks on widget
	m_picker->setSelectionFlags(QwtPicker::PointSelection | QwtPicker::ClickSelection);
 
}
 
void QSpectrogramPlot::OnPickerPointSelected(const QwtPolygon & poly)
{
	emit selectedPoint(poly[0]);
	m_picker->reset();
}

void QSpectrogramPlot::initWidget()
{
	delete m_picker;
	m_picker = new QwtPicker(this);
	connect(m_picker, SIGNAL(selected(const QwtPolygon &)), this, SLOT(OnPickerPointSelected(const QwtPolygon &)));

	// emit the position of clicks on widget
	m_picker->setSelectionFlags(QwtPicker::PointSelection | QwtPicker::ClickSelection);

}

void QSpectrogramPlot::OnPickerPointSelected(const QwtPolygon & poly)
{
	emit selectedPoint(poly[0]);
	m_picker->reset();
}

To copy to clipboard, switch view to plain text mode 

The rest to make sure that the Polygon is empty at the next click. I do not want it to be filled with points.

However the reset is not possible to be used - does not compile.

How would I do it then?

Also QwtPolygon would be the wrong argument if I want the points of the tracker, which must be QwtPolygonF. So how do I get the points of the tracker instead ?

EDIT:

Found a solution

m_picker = new QwtPlotPicker(this->canvas());
	connect(m_picker, SIGNAL(selected(const QwtDoublePoint &)), this, SLOT(OnPickerPointSelected(const QwtDoublePoint &)));
 
	// emit the position of clicks on widget
	m_picker->setSelectionFlags(QwtPicker::PointSelection | QwtPicker::ClickSelection);
 
}
 
void QSpectrogramPlot::OnPickerPointSelected(const QwtDoublePoint & p)
{
	QPointF point = p;
	emit selectedPoint(point);
	qDebug() << QString("x: %1, y: %2").arg(point.x()).arg(point.y()); 
}

m_picker = new QwtPlotPicker(this->canvas());
	connect(m_picker, SIGNAL(selected(const QwtDoublePoint &)), this, SLOT(OnPickerPointSelected(const QwtDoublePoint &)));

	// emit the position of clicks on widget
	m_picker->setSelectionFlags(QwtPicker::PointSelection | QwtPicker::ClickSelection);

}

void QSpectrogramPlot::OnPickerPointSelected(const QwtDoublePoint & p)
{
	QPointF point = p;
	emit selectedPoint(point);
	qDebug() << QString("x: %1, y: %2").arg(point.x()).arg(point.y()); 
}

To copy to clipboard, switch view to plain text mode