edit: Sorry for starting a new topic! I meant to reply to my original thread!

Hey,

After spending a few more hours on this, I just copied the "CurveData" class included with one of the examples to use as my object to store data points. Now I've run into another issue -- I don't get what function actually 'draws' the data, and whats the point of the QwtPlotDirectPainter class. Please take a look at my source:

Qt Code: 
  1. /**********	CURVEDATA CLASS DEFN *****************/
  2.  
  3. CurveData::CurveData():d_count(0)
  4. {}
  5.  
  6. void CurveData::append(double *x, double *y, int count)
  7. {
  8. 	//std::cerr << *x << "    " << *y << std::endl;
  9.     int newSize = ( (d_count + count) / 1000 + 1 ) * 1000;
  10.     if ( newSize > size() )
  11.     {
  12.         d_x.resize(newSize);
  13.         d_y.resize(newSize);
  14.     }
  15.  
  16.     for ( register int i = 0; i < count; i++ )
  17.     {
  18.         d_x[d_count + i] = x[i];
  19.         d_y[d_count + i] = y[i];
  20.     }
  21.     d_count += count;
  22. }
  23.  
  24. int CurveData::count() const
  25. {	return d_count;	}
  26.  
  27. int CurveData::size() const
  28. {	return d_x.size();	}
  29.  
  30. const double *CurveData::x() const
  31. {	return d_x.data();	}
  32.  
  33. const double *CurveData::y() const
  34. {	return d_y.data();	}
To copy to clipboard, switch view to plain text mode 

Qt Code: 
  1. /**********	DEVICEDISPLAY CLASS DEFN *************/
  2.  
  3. DeviceDisplay::DeviceDisplay(QWidget* parent):QwtPlot(parent)
  4. {
  5. 	_dataPainter = new QwtPlotDirectPainter();
  6. 	_dataInterval = new QwtDoubleInterval(0.0, 10.0);
  7.  
  8. 	setAutoReplot(false);
  9.  
  10. 	/* Improve Drawing Performance */
  11. 	canvas()->setPaintAttribute(QwtPlotCanvas::PaintCached, false);
  12. 	canvas()->setAttribute(Qt::WA_PaintOutsidePaintEvent, true);
  13. 	canvas()->setAttribute(Qt::WA_PaintOnScreen, true);
  14.  
  15. 	/* Draw the plot */
  16. 	// plot setup
  17. 	plotLayout()->setAlignCanvasToScales(true);
  18. 	setAxisTitle(QwtPlot::xBottom, "Time [s]");
  19. 	setAxisScale(QwtPlot::xBottom, _dataInterval->minValue(), _dataInterval->maxValue());
  20. 	setAxisScale(QwtPlot::yLeft, -720.0, 720.0);
  21.  
  22. 	// grid setup
  23. 	_displayGrid = new QwtPlotGrid();
  24. 	_displayGrid->enableX(true);		// major vertical gridlines
  25. 	_displayGrid->enableXMin(true);		// minor vertical gridlines
  26. 	_displayGrid->enableY(true);		// major vertical gridlines
  27. 	_displayGrid->enableYMin(true);		// minor vertical gridlines
  28. 	_displayGrid->attach(this);
  29.  
  30. 	// curve and data setup
  31. 	_dataPoints = new CurveData();
  32. 	_dataCurve = new QwtPlotCurve();
  33. 	_dataCurve->setStyle(QwtPlotCurve::Lines);
  34.  
  35.         const QColor &c = Qt::black;
  36.         _dataCurve->setSymbol(new QwtSymbol(QwtSymbol::XCross,
  37.             QBrush(c), QPen(c), QSize(10, 10)) );
  38.  
  39. 	_dataCurve->setRenderHint(QwtPlotItem::RenderAntialiased, true);
  40. 	_dataCurve->setPaintAttribute(QwtPlotCurve::ClipPolygons, false);
  41. 	_dataCurve->attach(this);
  42.  
  43. 	replot();
  44. }
  45.  
  46. DeviceDisplay::~DeviceDisplay()
  47. {
  48. 	delete _dataPainter;
  49. }
  50.  
  51. void DeviceDisplay::RefreshDisplay(double xNew, double yNew)
  52. {
  53. 	/* Redraw the display to incorporate any new points */
  54. 	_dataPoints->append(&xNew,&yNew,1);
  55.  
  56. 	_dataCurve->setRawSamples(	_dataPoints->x(),
  57. 								_dataPoints->y(),
  58. 								_dataPoints->count());
  59.  
  60.  
  61. 		_dataPainter->drawSeries(	_dataCurve,
  62. 									_dataCurve->dataSize()-1,
  63. 									_dataCurve->dataSize()-1);
  64.  
  65. }
To copy to clipboard, switch view to plain text mode 

The last part of the above code, the call to "drawSeries" -- doesn't do anything that I can notice except for give me a whole bunch of XServer errors (to be clear I can comment the call out and I'll still get the exact same plot with the lines drawn). So...
* I don't get when the points and lines are drawn if I comment the function out,
* What the "drawSeries" function is doing,
* Why am I getting X Server Errors?


And here's where I'm trying to draw stuff:

Qt Code: 
  1. Diag::Diag(QWidget *parent) :
  2.     QMainWindow(parent),
  3.     ui(new Ui::Diag)
  4. {
  5.     ui->setupUi(this);
  6.  
  7.    	// add display to the gui
  8.     _display = new DeviceDisplay(ui->horizontalLayoutWidget);
  9.     ui->horizontalLayout->addWidget(_display);
  10.  
  11.     // try plotting something
  12.     _display->RefreshDisplay(2,360);
  13.     _display->RefreshDisplay(3,260);
  14.     _display->RefreshDisplay(4,160);
  15.     _display->RefreshDisplay(5,60);
  16.     _display->RefreshDisplay(6,130);
  17.     _display->RefreshDisplay(7,240);
  18.  
  19. }
  20.  
  21. Diag::~RCNSDiag()
  22. {
  23.     delete ui;
  24. }
To copy to clipboard, switch view to plain text mode 


Here are the X Server errors if it helps:
Qt Code: 
  1. X Error: BadDrawable (invalid Pixmap or Window parameter) 9
  2.   Major opcode: 55 (X_CreateGC)
  3.   Resource id:  0x0
  4. X Error: BadDrawable (invalid Pixmap or Window parameter) 9
  5.   Major opcode: 55 (X_CreateGC)
  6.   Resource id:  0x0
  7. X Error: BadGC (invalid GC parameter) 13
  8.   Major opcode: 56 (X_ChangeGC)
  9.   Resource id:  0x0
  10. X Error: BadGC (invalid GC parameter) 13
  11.   Major opcode: 56 (X_ChangeGC)
  12.   Resource id:  0x0
  13. X Error: BadGC (invalid GC parameter) 13
  14.   Major opcode: 59 (X_SetClipRectangles)
  15.   Resource id:  0x0
  16. X Error: BadGC (invalid GC parameter) 13
  17.   Major opcode: 59 (X_SetClipRectangles)
  18.   Resource id:  0x0
  19. X Error: BadGC (invalid GC parameter) 13
  20.   Major opcode: 59 (X_SetClipRectangles)
  21.   Resource id:  0x0
  22. X Error: BadGC (invalid GC parameter) 13
  23.   Major opcode: 59 (X_SetClipRectangles)
  24.   Resource id:  0x0
  25. X Error: BadGC (invalid GC parameter) 13
  26.   Major opcode: 56 (X_ChangeGC)
  27.   Resource id:  0x0
  28. X Error: BadDrawable (invalid Pixmap or Window parameter) 9
  29.   Major opcode: 69 (X_FillPoly)
  30.   Resource id:  0x0
  31. X Error: BadGC (invalid GC parameter) 13
  32.   Major opcode: 56 (X_ChangeGC)
  33.   Resource id:  0x0
  34. X Error: BadDrawable (invalid Pixmap or Window parameter) 9
  35.   Major opcode: 69 (X_FillPoly)
  36.   Resource id:  0x0
  37. X Error: BadGC (invalid GC parameter) 13
  38.   Major opcode: 56 (X_ChangeGC)
  39.   Resource id:  0x0
  40. .... these errors continue for awhile
To copy to clipboard, switch view to plain text mode 

And the same output regardless of whether I comment the drawSeries call out or not:



I'd really appreciate any insight or advice... I'm having a lot of trouble figuring out what I'm doing wrong.


Regards,

kif