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Thread: qwt6, trouble with QwtPlotDirectPainter and simple example

  1. 17th June 2010, 22:45 #1
    kachofool
    kachofool is offline Novice
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    Default qwt6, trouble with QwtPlotDirectPainter and simple example

    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();	}
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    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. }
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    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. }
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    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
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    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
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  2. 18th June 2010, 15:34 #2
    kachofool
    kachofool is offline Novice
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    Default Re: qwt6, trouble with QwtPlotDirectPainter and simple example

    Hey,

    After a bit more experimentation,

    The line
    Qt Code: 
    1. canvas()->setAttribute(Qt::WA_PaintOutsidePaintEvent, true)
    To copy to clipboard, switch view to plain text mode 

    Is responsible for spitting out the X server errors. If I comment it out, the errors go away.

    I still can't figure out what's up with the graph plotting without explicitly calling
    Qt Code: 
    1. QwtPlotDirectPainter->drawSeries
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    . All I do is call
    Qt Code: 
    1. QwtPlotCurve->setRawSamples(...)
    To copy to clipboard, switch view to plain text mode 
    and the data still plots. I've made sure that autoReplot() is false. Could anyone explain this behaviour?
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