Plugin-signals-slots problem

[Misenko]

Hi all

I have application which load all plugins in directory plugins and show thier menus. I do this in class plugins:

bool Plugins::loadPlugins()
{
	QDir dir("./plugins");
	if (!dir.exists())
		return false;
 
	foreach (QString filename, dir.entryList(QDir::Files))
	{
		loader->setFileName(dir.absoluteFilePath(filename));
		QObject *couldBeFilter = loader->instance();
		if (couldBeFilter)
		{
			PluginInterface *plugin = qobject_cast<PluginInterface*>(couldBeFilter);
			if (plugin)
			{
				plugins.insert(plugin->name(), plugin);
				connect(plugin->menu(), SIGNAL(writeData(QByteArray)), this, SIGNAL(dataOut(QByteArray)));
			}
		}
	}
 
	return true;
}

bool Plugins::loadPlugins()
{
	QDir dir("./plugins");
	if (!dir.exists())
		return false;
	
	foreach (QString filename, dir.entryList(QDir::Files))
	{
		loader->setFileName(dir.absoluteFilePath(filename));
		QObject *couldBeFilter = loader->instance();
		if (couldBeFilter)
		{
			PluginInterface *plugin = qobject_cast<PluginInterface*>(couldBeFilter);
			if (plugin)
			{
				plugins.insert(plugin->name(), plugin);
				connect(plugin->menu(), SIGNAL(writeData(QByteArray)), this, SIGNAL(dataOut(QByteArray)));
			}
		}
	}
	
	return true;
}

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Then I have class PluginInterface:

class PluginInterface
{
 
public:
	virtual QString name() const = 0;
	virtual Menu* menu() const = 0;
};
 
Q_DECLARE_INTERFACE(PluginInterface, "sk.kimle.PluginInterface/0.1")

class PluginInterface
{
	
public:
	virtual QString name() const = 0;
	virtual Menu* menu() const = 0;
};

Q_DECLARE_INTERFACE(PluginInterface, "sk.kimle.PluginInterface/0.1")

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And now I am writing plugin. First I inherit from this interface this class:

class ProgramViewer : public QObject, PluginInterface
{
    Q_OBJECT
    Q_INTERFACES(PluginInterface)
 
public:
    ProgramViewer();
    virtual ~ProgramViewer();
	virtual QString name() const;
	virtual Menu* menu() const;
private:
	QString pluginName;
};

class ProgramViewer : public QObject, PluginInterface
{
    Q_OBJECT
    Q_INTERFACES(PluginInterface)

public:
    ProgramViewer();
    virtual ~ProgramViewer();
	virtual QString name() const;
	virtual Menu* menu() const;
private:
	QString pluginName;
};

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Function menu() return Menu object. It inherits from QWidget and have only virtual functions and slots:

class Menu : public QWidget
{
    Q_OBJECT
 
public:
    Menu(){}
    ~Menu(){}
    virtual void showWindow() const = 0;
    virtual void makeConnections() = 0;
public slots:
	virtual void readData(QByteArray array) =0;
signals:
	virtual void writeData(QByteArray array);
};

class Menu : public QWidget
{
    Q_OBJECT

public:
    Menu(){}
    ~Menu(){}
    virtual void showWindow() const = 0;
    virtual void makeConnections() = 0;
public slots:
	virtual void readData(QByteArray array) =0;
signals:
	virtual void writeData(QByteArray array);
};

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I have also class which inherits from Menu and this class has other widgets and functions.

class ProgramViewerMenu : public Menu
{
    Q_OBJECT
 
public:
	enum DataToSend
	{
		NewImage = 1,
		Pixels,
		Stop
	};
    ProgramViewerMenu();
    ~ProgramViewerMenu();
    void showWindow() const;
    void makeConnections();
    bool startBroadcasting();
    bool stopBroadcasting();
    QByteArray* takeShot(WId id);
    QByteArray* changePixels(QImage oldOne, QImage newOne);
public slots:
	void readData(QByteArray array);
	void broadcasting();
	void capture();
	void refreshList();
signals:
	void writeData(QByteArray array);
private:
	QLabel *title;
	QPushButton *broadcast;
	QPushButton *refresh;
	QGridLayout *grid;
	QListWidget *list;
	QTimer *timerRefresh;
	QTimer *timerBroadcast;
	QImage screen;
	WId id;
	bool isBroadcasting;
};

class ProgramViewerMenu : public Menu
{
    Q_OBJECT

public:
	enum DataToSend
	{
		NewImage = 1,
		Pixels,
		Stop
	};
    ProgramViewerMenu();
    ~ProgramViewerMenu();
    void showWindow() const;
    void makeConnections();
    bool startBroadcasting();
    bool stopBroadcasting();
    QByteArray* takeShot(WId id);
    QByteArray* changePixels(QImage oldOne, QImage newOne);
public slots:
	void readData(QByteArray array);
	void broadcasting();
	void capture();
	void refreshList();
signals:
	void writeData(QByteArray array);
private:
	QLabel *title;
	QPushButton *broadcast;
	QPushButton *refresh;
	QGridLayout *grid;
	QListWidget *list;
	QTimer *timerRefresh;
	QTimer *timerBroadcast;
	QImage screen;
	WId id;
	bool isBroadcasting;
};

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In some functions of this class I want to emit writeData(QByteArray) signal which is connected in the first class. But I ve got this error:
In function `ZN17ProgramViewerMenu11qt_metacallEN11QMetaObject 4CallEiPPv':
In function `ZN17ProgramViewerMenu11qt_metacastEPKc':
undefined reference to `Menu::qt_metacall(QMetaObject::Call, int, void**)'
undefined reference to `Menu::qt_metacast(char const*)'

I do not know whats wrong. I am not sure about those virtual functions, signals and slots and also I do not know if it is possible to connect something to plugin. Can anybody solve this? Thanks.

Sorry about my english.

[jpn]

Try re-running qmake.

[Misenko]

I ve done this many times becouse I ve been trying to change virtual functions, signals, slots etc.

[jpn]

Is menu.h listed in the .pro file?

[Misenko]

No it wasnt but I added it but nothing chenged.

[jpn]

Now re-run qmake once again.

[Misenko]

Thanks it works, but I dont know why

But I have another problem. I cant load plugin in Plugins class with function loadPlugins().
It found file and get filepath but it cant create QObject instance and I dont know why.

[jpn]

Thanks it works, but I dont know why

Headers containing the Q_OBJECT macro must be listed in the .pro file because qmake must create rules for running MOC on them.

But I have another problem. I cant load plugin in Plugins class with function loadPlugins().
It found file and get filepath but it cant create QObject instance and I dont know why.

Have you checked QPluginLoader::errorString()?

[Misenko]

Thank you man. I didnt know about this errorString function
Ok problem solved. Plugin appears correctly.