Dynamic load QT Plugin - symbol lookup error

[qlands]

Hi, I'm writing a program that uses plugins to extend it. I followed the examples in QT. But when I run the application it gives the error: symbol lookup error: /home/cquiros/MyApplication/plugins/libtnkbasicplugins.so: undefined symbol: _ZN16tnkBasicPolygons13createPolygonE7QString.

From the error I can see that the problem is in the function createPolygon. This fuction is private for the plugin.

If I remove the private function createPolygon. The application works just fine.

Any idea what I am doing wrong?

Many thanks.

Here is the code:

tnkinterfaces.h


#ifndef TNKINTERFACES_H
#define TNKINTERFACES_H

#include <QtPlugin>
#include "tnkdelegatorfactory.h"

class QStringList;
class QIcon;

class tnkPolygonInterface
{
public:
virtual ~tnkPolygonInterface() {}
virtual QStringList pluginNames() const = 0;
virtual QList<QIcon> pluginIcons() = 0;
virtual tnkPolygonSymbol* constructNewItem(const QString &pluginName, bool inDesignMode) = 0;
virtual tnkPolygonSymbol* loadItemFromData(const QString &pluginName, QByteArray &data, bool inDesignMode) = 0;
};

Q_DECLARE_INTERFACE(tnkPolygonInterface,"com.personal.MyApplication.tnkPolygonInterface/1.0")

#endif // TNKINTERFACES_H


tnkbasicplugins.h


#ifndef TNKBASICPLUGINS_H
#define TNKBASICPLUGINS_H

#include <QtGui>
#include <QObject>
#include <src/tnkinterfaces.h>

class tnkBasicPolygons : public QObject, public tnkPolygonInterface
{
Q_OBJECT
Q_INTERFACES(tnkPolygonInterface)
public:
QStringList pluginNames() const;
QList<QIcon> pluginIcons();
tnkPolygonSymbol* constructNewItem(const QString &pluginName, bool inDesignMode);
tnkPolygonSymbol* loadItemFromData(const QString &pluginName, QByteArray &data, bool inDesignMode);
private:
QPolygonF createPolygon(QString polygonType);
};

#endif // TNKBASICPLUGINS_H


in the .h createPolygon(QString polygonType) is private and not declared in the interfaces.

tnkbasicplugins.cpp


#include "tnkbasicplugins.h"


QStringList tnkBasicPolygons::pluginNames() const
{
return QStringList() << tr("Box");
}


QList<QIcon> tnkBasicPolygons::pluginIcons()
{
QList<QIcon> result;
QImage image;
QPainter painter(&image);

// Create a 32x32 representation of the box
// and appends it to the list of icons
QGraphicsScene scene;
scene.setSceneRect(QRectF(0,0,101,101));
scene.addPolygon(createPolygon("Box"));
scene.render(&painter);
image.scaledToHeight(32);
image.scaledToWidth(32);
result.append(QIcon(QPixmap::fromImage(image)));


return result;
}

tnkPolygonSymbol* tnkBasicPolygons::constructNewItem(const QString &pluginName, bool inDesignMode)
{
tnkPolygonSymbol *result;
result = new tnkPolygonSymbol(0,0,inDesignMode); //Must change
if (pluginName == tr("Box"))
{
QPolygonF sqPolygon;
sqPolygon << QPointF(-100, -100) << QPointF(100, -100)
<< QPointF(100, 100) << QPointF(-100, 100)
<< QPointF(-100, -100);
result->setPolygon(createPolygon("Box"));

//Need to see how to save data!

}
return result;
}

tnkPolygonSymbol* tnkBasicPolygons::loadItemFromData(const QString &pluginName, QByteArray &data, bool inDesignMode)
{
tnkPolygonSymbol *result;
result = new tnkPolygonSymbol(0,0,inDesignMode); //Must change
if (pluginName == tr("Box"))
{

result->setPolygon(createPolygon("Box"));

//Need to see how to save data!

}
return result;
}


QPolygonF createPolygon(QString polygonType)
{
QPolygonF sqPolygon;
if (polygonType == "Box")
{
sqPolygon << QPointF(-100, -100) << QPointF(100, -100)
<< QPointF(100, 100) << QPointF(-100, 100)
<< QPointF(-100, -100);
}
return sqPolygon;
}

Q_EXPORT_PLUGIN2(tnk_basicpolygons, tnkBasicPolygons)

[SixDegrees]

What happens if you make createPolygon() protected rather than private?

[qlands]

The same error happens whether is private, protected or public.

[SixDegrees]

It sounds like the loader can't find your plugin. Are you checking results to see if it located it, loaded it and cast it to the correct type?

[qlands]

oh Man!!!! After maybe 8 hours in this crazy bug I just realized that I declared in the cpp:

QPolygonF createPolygon(QString polygonType) and not QPolygonF tnkBasicPolygons::createPolygon(QString polygonType)

And that was the error!..

Many thanks for the replies!