Qwt Problem

[jpn]

Sounds like you are manipulating the widget outside the main GUI thread, is this true?

Thread Support in Qt:

Although QObject is reentrant, the GUI classes, notably QWidget and all its subclasses, are not reentrant. They can only be used from the main thread.

[allensr]

Well, Im not sure. I am populating the TableWidget with data from a TreeWidget via a drag and drop. Is that manipulating the widget outside the main GUI thread? Again, I only have problems if I select items in the TableWidget.

[jpn]

Ok good, then the problem is not with threads. I was suspecting you tried to do the plotting in a "worker" thread..

To be honest, I can't find any pitfall in your code, but does it make any difference if you revise the function to look something like this:

void cPlot2d::setup2dPlot()
{
	int totalRowCount = this->mTableWidget->rowCount();
	QList<QTableWidgetItem *> selected = this->mTableWidget->selectedItems();
	QTableWidgetItem *item;
 
	QwtArray<double> x;
	QwtArray<double> y;
 
	if(totalRowCount > 0)
	{
		//Have any items been selected
		if(selected.count() > 0)
		{
			foreach(item, selected)
			{
				bool ok = false;
				double value = item->text().toDouble(&ok);
				//For MVC, get the data out of the model
				//Data is stored contiguously in list, so got to figure out what column data is in
				//x=0 y=1
				if(item->column() == 0)
				{
					if(ok && !item->text().isEmpty())
						x.push_back(value);
				}
				else
				{
					if(ok && !item->text().isEmpty())
						y.push_back(value);
				}
			}
		}
		//No items selected, load up entire table
		else
		{
			for(int i=0; i<totalRowCount; ++i)
			{
				//For MVC, get the data out of the model
				QTableWidgetItem* item0 = mTableWidget->item(i,0);
				QTableWidgetItem* item1 = mTableWidget->item(i,1);
				x.push_back(item0->text().toDouble());
				y.push_back(item1->text().toDouble());
			}
		}
		// Set up Qwt Plot stuff
		QwtPlot * plot(new QwtPlot(this));
		plot->setTitle("2D Plot");
		// axis titles
		plot->setAxisTitle(QwtPlot::xBottom, "x");
		plot->setAxisTitle(QwtPlot::yLeft, "y");
 
		// curve
		QwtPlotCurve * curve(new QwtPlotCurve("Curve 1"));
		curve->attach(plot);
		// data
		curve->setData(x, y);
		// pen
		curve->setPen(QPen(QColor(0, 0, 200)));
		// style
		curve->setStyle(QwtPlotCurve::Lines);
 
		plot->replot();
 
		cMainWindow::getInstance()->mWorkspace->addWindow(plot)->show();
 
	}
	else
	{
		cout << " NO DATA TO PLOT!! " << endl;
		return;
	}
} // cPlot2d::setup2dPlot

void cPlot2d::setup2dPlot()
{
	int totalRowCount = this->mTableWidget->rowCount();
	QList<QTableWidgetItem *> selected = this->mTableWidget->selectedItems();
	QTableWidgetItem *item;

	QwtArray<double> x;
	QwtArray<double> y;

	if(totalRowCount > 0)
	{
		//Have any items been selected
		if(selected.count() > 0)
		{
			foreach(item, selected)
			{
				bool ok = false;
				double value = item->text().toDouble(&ok);
				//For MVC, get the data out of the model
				//Data is stored contiguously in list, so got to figure out what column data is in
				//x=0 y=1
				if(item->column() == 0)
				{
					if(ok && !item->text().isEmpty())
						x.push_back(value);
				}
				else
				{
					if(ok && !item->text().isEmpty())
						y.push_back(value);
				}
			}
		}
		//No items selected, load up entire table
		else
		{
			for(int i=0; i<totalRowCount; ++i)
			{
				//For MVC, get the data out of the model
				QTableWidgetItem* item0 = mTableWidget->item(i,0);
				QTableWidgetItem* item1 = mTableWidget->item(i,1);
				x.push_back(item0->text().toDouble());
				y.push_back(item1->text().toDouble());
			}
		}
		// Set up Qwt Plot stuff
		QwtPlot * plot(new QwtPlot(this));
		plot->setTitle("2D Plot");
		// axis titles
		plot->setAxisTitle(QwtPlot::xBottom, "x");
		plot->setAxisTitle(QwtPlot::yLeft, "y");

		// curve
		QwtPlotCurve * curve(new QwtPlotCurve("Curve 1"));
		curve->attach(plot);
		// data
		curve->setData(x, y);
		// pen
		curve->setPen(QPen(QColor(0, 0, 200)));
		// style
		curve->setStyle(QwtPlotCurve::Lines);

		plot->replot();

		cMainWindow::getInstance()->mWorkspace->addWindow(plot)->show();

	}
	else
	{
		cout << " NO DATA TO PLOT!! " << endl;
		return;
	}
} // cPlot2d::setup2dPlot

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All I did was cleaning up the unnecessary usage of model indexes which you actually shouldn't need while working with convenience views. If it still crashes, could you please post the backtrace from the debugger? And could you tell the exact version of Qt you are using as well?