qwtPlot->replot() results in segmentation fault

[kaizimir]

Here is the class generated by the designer, which instantiats qwtPlot:

QT_BEGIN_NAMESPACE
 
class Ui_MainWindow
{
public:
    QWidget *centralwidget;
    QwtPlot *qwtPlot;       // here
    QMenuBar *menubar;
    QStatusBar *statusbar;
 
    void setupUi(QMainWindow *MainWindow)
    {
    if (MainWindow->objectName().isEmpty())
        MainWindow->setObjectName(QString::fromUtf8("MainWindow"));
    MainWindow->resize(800, 600);
    centralwidget = new QWidget(MainWindow);
    centralwidget->setObjectName(QString::fromUtf8("centralwidget"));
    qwtPlot = new QwtPlot(centralwidget);    // here
    qwtPlot->setObjectName(QString::fromUtf8("qwtPlot"));  
    qwtPlot->setGeometry(QRect(40, 30, 721, 501));  
    MainWindow->setCentralWidget(centralwidget);
    menubar = new QMenuBar(MainWindow);
    menubar->setObjectName(QString::fromUtf8("menubar"));
    menubar->setGeometry(QRect(0, 0, 800, 24));
    MainWindow->setMenuBar(menubar);
    statusbar = new QStatusBar(MainWindow);
    statusbar->setObjectName(QString::fromUtf8("statusbar"));
    MainWindow->setStatusBar(statusbar);
 
    retranslateUi(MainWindow);
 
    QMetaObject::connectSlotsByName(MainWindow);
    } // setupUi
 
    void retranslateUi(QMainWindow *MainWindow)
    {
    MainWindow->setWindowTitle(QApplication::translate("MainWindow", "MainWindow", 0, QApplication::UnicodeUTF8));
    Q_UNUSED(MainWindow);
    } // retranslateUi
 
};
 
namespace Ui {
    class MainWindow: public Ui_MainWindow {};
} // namespace Ui
 
QT_END_NAMESPACE

QT_BEGIN_NAMESPACE

class Ui_MainWindow
{
public:
    QWidget *centralwidget;
    QwtPlot *qwtPlot;       // here
    QMenuBar *menubar;
    QStatusBar *statusbar;

    void setupUi(QMainWindow *MainWindow)
    {
    if (MainWindow->objectName().isEmpty())
        MainWindow->setObjectName(QString::fromUtf8("MainWindow"));
    MainWindow->resize(800, 600);
    centralwidget = new QWidget(MainWindow);
    centralwidget->setObjectName(QString::fromUtf8("centralwidget"));
    qwtPlot = new QwtPlot(centralwidget);    // here
    qwtPlot->setObjectName(QString::fromUtf8("qwtPlot"));  
    qwtPlot->setGeometry(QRect(40, 30, 721, 501));  
    MainWindow->setCentralWidget(centralwidget);
    menubar = new QMenuBar(MainWindow);
    menubar->setObjectName(QString::fromUtf8("menubar"));
    menubar->setGeometry(QRect(0, 0, 800, 24));
    MainWindow->setMenuBar(menubar);
    statusbar = new QStatusBar(MainWindow);
    statusbar->setObjectName(QString::fromUtf8("statusbar"));
    MainWindow->setStatusBar(statusbar);

    retranslateUi(MainWindow);

    QMetaObject::connectSlotsByName(MainWindow);
    } // setupUi

    void retranslateUi(QMainWindow *MainWindow)
    {
    MainWindow->setWindowTitle(QApplication::translate("MainWindow", "MainWindow", 0, QApplication::UnicodeUTF8));
    Q_UNUSED(MainWindow);
    } // retranslateUi

};

namespace Ui {
    class MainWindow: public Ui_MainWindow {};
} // namespace Ui

QT_END_NAMESPACE

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And this is the header of the M_MainWindow class I posted yesterday:

class M_MainWindow : public QMainWindow,
			private Ui::MainWindow
{
	Q_OBJECT
 
	public:
		M_MainWindow ( QWidget *parent = 0 );
 
		~M_MainWindow();
 
};

class M_MainWindow : public QMainWindow,
			private Ui::MainWindow
{
	Q_OBJECT
	
	public:
		M_MainWindow ( QWidget *parent = 0 );

		~M_MainWindow();

};

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I think, the private Ui::MainWindow inheritance is the reason, why I don't need the ui.*...

I am really sorry to get on your nervs every day. But it is a real pity to have such a show stopper as a newby to C++, Qt and qwt when everything else works fine.

[kaizimir]

Hey,

I found the problem and I must admitt, that it is not related to qwt.

@jmsbc: You were right from the beginning, that it is a problem of instantiation and that the plot widget isn't accessible from where I wanted to use it.

I am doing it now by handing over a pointer to the qwt widget to the class that uses the plot. I am not very happy with that solution and hope to find a way with inheritance.

Thanks to all,

kai

[gudlaugu]

I know I am a bit late to this thread, but you forgot to call setupUi(this) in the constructor of M_Plot.

[windsword]

this might be somewhat related, I found that replot() works well when I rescale my x-axis in Mac OS platform, but it does not respond/work when I use this in Linux? It's kind of strange. I wonder if this is related?

I just posted the details in a separate thread.