Hello,

I am new to the world of GUI and I am having some problems with building a programm to plot straight lines.
It would be very nice, if somebody could help me...
I am using Visual Studio 2010 Express.
Both Qt and QWT are succesfully integrated and are tested to work properly.
I thought it wold work like this:

- The parameters (Offset + Gradient) of the straight line are committed in the Main Window

- Pushing the Plot-Button should call a Constructor, that creates a QWT PLot, called Graph,
and inserts a straight line with the committed paramters. (Plot.h/cpp)

- Furthermore a QDialog should be created

-The previously created Graph should now be inserted in the QDialog

- After all the new Window should open and display the straight line


My Problem is, that after succesfully compiling and linking the mainwindow opens, but pushing the plot-button
results in the programms shutdown with errorcode 1.
If I leave out the call of the Graph constructor in Plotm::draw, the programm runs completely succesfully but the new window is empty of course.
So in my oppinion I do something wrong in the constructor...

Thank you for your help !

Plotm.h:
Qt Code: 
  1. #ifndef PLOTM_H
  2.  
  3. #define PLOTM_H
  4. #include "ui_Plot10.h"
  5. #include <qdialog.h>
  6.  
  7.  class Plotm : public QMainWindow, public Ui::MainWindow
  8. {
  9.  
  10. 		Q_OBJECT
  11.  
  12. 		public:
  13.  
  14.                 Plotm  (QMainWindow *parent = 0);
  15.  
  16.                 ~ Plotm ();
  17.  
  18. 		private slots:
  19.  
  20. 				void draw();
  21. };
  22.  
  23. #endif //PLOTM_H
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Plotm.cpp:
Qt Code: 
  1. #include "Plotm.h"
  2. #include "Plot.h"
  3.  
  4.  
  5. Plotm::Plotm(QMainWindow *parent) : QMainWindow(parent)
  6. {
  7. 	setupUi(this);
  8.     xmi-> setText("0");
  9. 	ymi-> setText("0");
  10.  
  11. 	connect(plotb, SIGNAL(clicked()), this, SLOT(draw()));
  12. }
  13.  
  14. Plotm::~Plotm()
  15. {}
  16.  
  17. void Plotm::draw()
  18. {
  19. 	Graph* plot ;
  20. 	QDialog* nw;
  21. 	nw = new QDialog(this, Qt::Window);
  22.  
  23. 	int ava; //Gradient
  24. 	int bva; //Offset
  25.  
  26. 	ava = aval->text().toDouble();
  27. 	bva = bval->text().toDouble();
  28.  
  29.  
  30. 	plot = new Graph(ava,bva,nw);
  31. 	plot->show();
  32. 	nw->show();
  33. }
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Plot.h:
Qt Code: 
  1. #ifndef PLOT_H
  2. #define PLOT_H
  3.  
  4. #include <qapplication.h>
  5. #include <qlayout.h>
  6. #include <qwt_plot.h>
  7. #include <qwt_plot_marker.h>
  8. #include <qwt_plot_curve.h>
  9. #include <qwt_legend.h>
  10. #include <qwt_series_data.h>
  11. #include <qwt_plot_canvas.h>
  12. #include <qwt_plot_panner.h>
  13. #include <qwt_plot_magnifier.h>
  14. #include <qwt_text.h>
  15. #include <qwt_math.h>
  16. #include <math.h>
  17. #include <qwt_symbol.h>
  18. #include <QtGui>
  19.  
  20. class Graph : public QwtPlot
  21. {
  22.  
  23. public:
  24.    	int aval;//Gradient
  25. 	int bval;//Offset
  26.  
  27. 	double xval[100];
  28. 	double yval[100];
  29.  
  30. 	//Constructor which commits the parameters of the straight line to create
  31. 	Graph(int avala,int bvala, QWidget* parent); 
  32. };
  33.  
  34. #endif
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Plot.cpp:
Qt Code: 
  1. #include <qapplication.h>
  2. #include <qlayout.h>
  3. #include <qwt_plot.h>
  4. #include <qwt_plot_marker.h>
  5. #include <qwt_plot_curve.h>
  6. #include <qwt_legend.h>
  7. #include <qwt_series_data.h>
  8. #include <qwt_plot_canvas.h>
  9. #include <qwt_plot_panner.h>
  10. #include <qwt_plot_magnifier.h>
  11. #include <qwt_text.h>
  12. #include <qwt_math.h>
  13. #include <math.h>
  14. #include <qwt_symbol.h>
  15. #include "Plot.h"
  16. #include <qwt_plot_grid.h>
  17. #include "Plotm.h"
  18. #include "Plot.h"
  19.  
  20.  
  21. Graph::Graph(int avala,int bvala,QWidget *parent) 
  22. {
  23.  
  24. 	aval = avala;
  25. 	bval = bvala;
  26.  
  27.     setAutoFillBackground( true );
  28.     setPalette( QPalette( QColor( 165, 193, 228 ) ) );
  29.  
  30.     setTitle("Plot 1.0");
  31.     insertLegend(new QwtLegend(), QwtPlot::RightLegend);
  32.  
  33.     // axes 
  34.     setAxisTitle(xBottom, "x -->" );
  35.     setAxisScale(xBottom, 0, 10);
  36.  
  37.     setAxisTitle(yLeft, "y -->");
  38.     setAxisScale(yLeft, 0, 10);
  39.  
  40.     // canvas
  41.     canvas()->setLineWidth( 1 );
  42.     canvas()->setFrameStyle( QFrame::Box | QFrame::Plain );
  43.     canvas()->setBorderRadius( 15 );
  44.  
  45.     QPalette canvasPalette( Qt::white );
  46.     canvasPalette.setColor( QPalette::Foreground, QColor( 133, 190, 232 ) );
  47.     canvas()->setPalette( canvasPalette );
  48.  
  49. 	for(int i=0; i<100;i++)
  50.     {   
  51.         xval[i] = double(i) * 1/10;
  52.         yval[i] = this->aval * xval[i] + this->bval;
  53.     }
  54.  
  55. 	// Insert new curves
  56.  
  57. 	QwtPlotCurve * d_curves = new QwtPlotCurve("y = a*x+b");
  58.     d_curves->setRenderHint(QwtPlotItem::RenderAntialiased);
  59.     d_curves->setLegendAttribute(QwtPlotCurve::LegendShowLine, true);
  60.     d_curves->setPen(QPen(Qt::green));
  61. 	d_curves->setRawSamples(xval, yval, 100);
  62. 	d_curves->attach(this);
  63.  
  64. 	replot();
  65. }
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