Inheriting from QwtPlotCurve problems

[dbrmik]

Hi

I have a my Curve class derived from QwtPlotCurve as shown

class Curve :public QwtPlotCurve  {
	Q_OBJECT;
public:
	Curve(QWidget* parent, QString s,QColor colour,int size);
	virtual ~Curve();
	QCheckBox* checkBox;
	float* plotData;
	int size;
signals:
	void doPlotUpdate();
};
 
Curve::Curve(QWidget* parent,QString s,QColor color,int size):
 QwtPlotCurve(s),
 checkBox(new QCheckBox(s)),
 plotData(new float[size]),
 size(size)
{
	setPen(QPen(color));
	QObject::connect(this->checkBox,SIGNAL(stateChanged(int)),parent, SLOT(updatePlots()));
}

class Curve :public QwtPlotCurve  {
	Q_OBJECT;
public:
	Curve(QWidget* parent, QString s,QColor colour,int size);
	virtual ~Curve();
	QCheckBox* checkBox;
	float* plotData;
	int size;
signals:
	void doPlotUpdate();
};

Curve::Curve(QWidget* parent,QString s,QColor color,int size):
 QwtPlotCurve(s),
 checkBox(new QCheckBox(s)),
 plotData(new float[size]),
 size(size)
{
	setPen(QPen(color));
	QObject::connect(this->checkBox,SIGNAL(stateChanged(int)),parent, SLOT(updatePlots()));
}

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My intention is to connect the signal from the checkbox to the slot updatePlots so that when the checkbox is enabled the plot is displayed. I am getting the following linking error

debug\moc_QwtSeahawkPlot.cpp:42: error: `staticMetaObject' is not a member of `QwtPlotCurve'
debug\moc_QwtSeahawkPlot.cpp: In member function `virtual void* Curve::qt_metacast(const char*)':
debug\moc_QwtSeahawkPlot.cpp:56: error: `qt_metacast' is not a member of `QwtPlotCurve'
debug\moc_QwtSeahawkPlot.cpp: In member function `virtual int Curve::qt_metacall(QMetaObject::Call, int, void**)':
debug\moc_QwtSeahawkPlot.cpp:61: error: `qt_metacall' is not a member of `QwtPlotCurve'
debug\moc_QwtSeahawkPlot.cpp: In member function `void Curve::doPlotUpdate()':

Also when I call attach I get the following compilation error.

mycurve=new Curve(this,"Input Data","yellow",1024);
mycurve->attach(plot);

mycurve=new Curve(this,"Input Data","yellow",1024);
mycurve->attach(plot);

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c:/Qt/4.5.0/include/qwt./qwt_plot_item.h: In member function `void QwtSeahawkPlot::updatePlots()':
c:/Qt/4.5.0/include/qwt./qwt_plot_item.h:117: error: `void QwtPlotItem::attach(QwtPlot*)' is inaccessible
SeaHawkDebug\QwtSeahawkPlot.cpp:127: error: within this context
SeaHawkDebug\QwtSeahawkPlot.cpp:127: error: `QwtPlotItem' is not an accessible base of `Curve'
mingw32-make[1]: *** [debug/QwtSeahawkPlot.o] Error 1

Could someone help me out

Regards

[Uwe]

QwtPlotCurve is no QObject.

[dbrmik]

Thanks

OK, if I inherit from QObject and include the QObject macro as show

class Curve :public QObject , QwtPlotCurve  {
	Q_OBJECT;
public:
	Curve(QWidget* parent, QString s,QColor colour,int size);

class Curve :public QObject , QwtPlotCurve  {
	Q_OBJECT;
public:
	Curve(QWidget* parent, QString s,QColor colour,int size);

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The program compiles fine, however if I try and access QwtPlotCurve methods

mycurve=new Curve(this,"Input Data","yellow",x_samples);
mycurve->attach(plot);

mycurve=new Curve(this,"Input Data","yellow",x_samples);
mycurve->attach(plot);

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I get the following error

c:/Qt/4.5.0/include/qwt./qwt_plot_item.h: In constructor `QwtSeahawkPlot::QwtSeahawkPlot(QMainWindow*, SeaHawk*)':
c:/Qt/4.5.0/include/qwt./qwt_plot_item.h:117: error: `void QwtPlotItem::attach(QwtPlot*)' is inaccessible
mingw32-make[1]: Leaving directory `D:/Projects/SeaHawkPC/Eclipse/QtSeaHawkPlots-Inheritance'
SeaHawkDebug\QwtSeahawkPlot.cpp:112: error: within this context
SeaHawkDebug\QwtSeahawkPlot.cpp:112: error: `QwtPlotItem' is not an accessible base of `Curve'

What am I doing wrong?

Thanks

[huseyinkozan]

Hi,
Maybe this works:

class Curve :public QwtPlotCurve, public QObject  {
...

class Curve :public QwtPlotCurve, public QObject  {
...

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Hüseyin

[dbrmik]

No

I'm afraid it doesn't, I get the same error and a compiler warning

Warning: Class Curve inherits from two QObject subclasses QwtPlotCurve and QObject. This is not supported!

[dbrmik]

Hi

I've solved the problem temporarily by not inheriting from QObject and not using the Q_Object macro. I dont know why it works but it does for now

Thanks everyone