strange error in connect()

[quickNitin]

bqgis_plugin_tcpcock_la-tcpcock.Tpo -c tcpcock.cpp -fPIC -DPIC -o .libs/libqgis_plugin_tcpcock_la-tcpcock.o
tcpcock.cpp: In member function 'virtual void tcpCock::initGui()':
tcpcock.cpp:105: error: no matching function for call to 'tcpCock::connect(QgsMapCanvas*, const char [28], tcpCock* const, const char [25])'
/usr/local/Trolltech/Qt-4.1.2//include/QtCore/qobject.h:174: note: candidates are: static bool QObject::connect(const QObject*, const char*, const QObject*, const char*, Qt::ConnectionType)
/usr/local/Trolltech/Qt-4.1.2//include/QtCore/qobject.h:274: note: bool QObject::connect(const QObject*, const char*, const char*, Qt::ConnectionType) const
make[5]: *** [libqgis_plugin_tcpcock_la-tcpcock.lo] Error 1
make[5]: Leaving directory `/home1/qgis/src/plugins/tcpCock'
make[4]: *** [all] Error 2
make[4]: Leaving directory `/home1/qgis/src/plugins/tcpCock'

code of initGui():

void tcpCock::initGui()
{
 
  // Create the action for tool
  mQActionPointer = new QAction(QIcon(":/tcpcock/tcpcock.png"),"track", this);
  // Set the what's this text
  mQActionPointer->setWhatsThis(tr("Replace this with a short description of the what the plugin does"));
  // Connect the action to the run
  connect(mQActionPointer, SIGNAL(activated()), this, SLOT(run()));
  // Add the toolbar
  mToolBarPointer = new QToolBar((QMainWindow *) mQGisApp, "tcpCock");
  mToolBarPointer->setLabel("track");
  // Add the to the toolbar
  mQGisIface->addToolBarIcon(mQActionPointer);
  mQGisIface->addPluginMenu("&tcpCock", mQActionPointer);
	connect(mQGisIface->getMapCanvas(),SIGNAL(renderComplete(QPainter *)),this, SLOT(savePainter(QPainter *)));//line no 105
}

void tcpCock::initGui()
{

  // Create the action for tool
  mQActionPointer = new QAction(QIcon(":/tcpcock/tcpcock.png"),"track", this);
  // Set the what's this text
  mQActionPointer->setWhatsThis(tr("Replace this with a short description of the what the plugin does"));
  // Connect the action to the run
  connect(mQActionPointer, SIGNAL(activated()), this, SLOT(run()));
  // Add the toolbar
  mToolBarPointer = new QToolBar((QMainWindow *) mQGisApp, "tcpCock");
  mToolBarPointer->setLabel("track");
  // Add the to the toolbar
  mQGisIface->addToolBarIcon(mQActionPointer);
  mQGisIface->addPluginMenu("&tcpCock", mQActionPointer);
	connect(mQGisIface->getMapCanvas(),SIGNAL(renderComplete(QPainter *)),this, SLOT(savePainter(QPainter *)));//line no 105
}

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both QgsMapCanvas and tcpCock inherits QObject. * mQGisIface is a private member of tcpCock and

[e8johan]

When inheriting QObject, you must do so publically and QObject must appear first in the list if you use multiple inheritance, e.g. class Foo : public QObject, ... {};

The error message does indicate that they do not inherit QObject, but it could be a missing "public" too.

[quickNitin]

ya i have taken care of that and i have inherited QObject publically first than anyother class.
declaration code is:

**************/
#ifndef tcpCock_H
#define tcpCock_H
 
//QT4 includes
#include <QObject>
#include <QPainter>
#include <QtNetwork>
#include <QtGui>
//QGIS includes
#include <qgisapp.h>
#include "../qgisplugin.h"
 
//forward declarations
class QToolBar;
 
/**
* \class Plugin
* \brief [name] plugin for QGIS
* [description]
*/
class tcpCock:public QObject , public QgisPlugin
{
  Q_OBJECT;
  public:
  /** 
  * Constructor for a plugin. The QgisApp and QgisIface pointers are passed by 
  * QGIS when it attempts to instantiate the plugin.
  * @param Pointer to the QgisApp object
  * @param Pointer to the QgisIface object. 
   */
  tcpCock(QgisApp * theApplication, QgisIface * theInterface);
  //! Destructor
  virtual ~tcpCock();
 
public slots:
  //! init the gui
  virtual void initGui();
  //! Show the dialog box
  void run();
  //! unload the plugin
  void unload();
  //! show the help document
  void help();
  //!draw a raster layer in the qui
  void drawRasterLayer(QString);
  //! Add a vector layer given vectorLayerPath, baseName, providerKey ("ogr" or "postgres");
  void drawVectorLayer(QString,QString,QString);
 
private:
  int mPluginType;
  //! Pointer to our toolbar
  QToolBar *mToolBarPointer;
  //! Pionter to QGIS main application object
  QgisApp *mQGisApp;
  //! Pointer to the QGIS interface object
  QgisIface *mQGisIface;
  //!pointer to the qaction for this plugin
  QAction * mQActionPointer;
	int x,y;
	QTcpServer *tcpServer;
	QTcpSocket *tcpSocket;
	QPainter *savedPainter;
public slots:
	void savePainter(QPainter *);
	void settingServer(bool);
	void dataAvailable();
	void activatingNewConnection();
	void render();
signals:
	//void dataFound();
	void startRender();
};
 
#endif //tcpCock_H

**************/
#ifndef tcpCock_H
#define tcpCock_H

//QT4 includes
#include <QObject>
#include <QPainter>
#include <QtNetwork>
#include <QtGui>
//QGIS includes
#include <qgisapp.h>
#include "../qgisplugin.h"

//forward declarations
class QToolBar;

/**
* \class Plugin
* \brief [name] plugin for QGIS
* [description]
*/
class tcpCock:public QObject , public QgisPlugin
{
  Q_OBJECT;
  public:
  /** 
  * Constructor for a plugin. The QgisApp and QgisIface pointers are passed by 
  * QGIS when it attempts to instantiate the plugin.
  * @param Pointer to the QgisApp object
  * @param Pointer to the QgisIface object. 
   */
  tcpCock(QgisApp * theApplication, QgisIface * theInterface);
  //! Destructor
  virtual ~tcpCock();

public slots:
  //! init the gui
  virtual void initGui();
  //! Show the dialog box
  void run();
  //! unload the plugin
  void unload();
  //! show the help document
  void help();
  //!draw a raster layer in the qui
  void drawRasterLayer(QString);
  //! Add a vector layer given vectorLayerPath, baseName, providerKey ("ogr" or "postgres");
  void drawVectorLayer(QString,QString,QString);
  
private:
  int mPluginType;
  //! Pointer to our toolbar
  QToolBar *mToolBarPointer;
  //! Pionter to QGIS main application object
  QgisApp *mQGisApp;
  //! Pointer to the QGIS interface object
  QgisIface *mQGisIface;
  //!pointer to the qaction for this plugin
  QAction * mQActionPointer;
	int x,y;
	QTcpServer *tcpServer;
	QTcpSocket *tcpSocket;
	QPainter *savedPainter;
public slots:
	void savePainter(QPainter *);
	void settingServer(bool);
	void dataAvailable();
	void activatingNewConnection();
	void render();
signals:
	//void dataFound();
	void startRender();
};

#endif //tcpCock_H

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[quickNitin]

Also that has been the case i would have got problem with other connects also.

void tcpCock::run()
{
  tcpCockGui *myPluginGui=new tcpCockGui(mQGisApp, QgisGui::ModalDialogFlags);
  //listen for when the layer has been made so we can draw it
  connect(myPluginGui, SIGNAL(drawRasterLayer(QString)), this, SLOT(drawRasterLayer(QString)));
  connect(myPluginGui, SIGNAL(drawVectorLayer(QString,QString,QString)), this, SLOT(drawVectorLayer(QString,QString,QString)));
 
	connect(myPluginGui,SIGNAL(isCheckBoxClicked(bool)),this,SLOT(settingServer(bool)));
	connect(this,SIGNAL(startRender()),this,SLOT(render()));
myPluginGui->show();
}
 
// Unload the plugin by cleaning up the GUI
void tcpCock::unload()
{
  // remove the GUI
  mQGisIface->removePluginMenu("&tcpCock",mQActionPointer);
  mQGisIface->removeToolBarIcon(mQActionPointer);
  delete mQActionPointer;
}

void tcpCock::run()
{
  tcpCockGui *myPluginGui=new tcpCockGui(mQGisApp, QgisGui::ModalDialogFlags);
  //listen for when the layer has been made so we can draw it
  connect(myPluginGui, SIGNAL(drawRasterLayer(QString)), this, SLOT(drawRasterLayer(QString)));
  connect(myPluginGui, SIGNAL(drawVectorLayer(QString,QString,QString)), this, SLOT(drawVectorLayer(QString,QString,QString)));

	connect(myPluginGui,SIGNAL(isCheckBoxClicked(bool)),this,SLOT(settingServer(bool)));
	connect(this,SIGNAL(startRender()),this,SLOT(render()));
myPluginGui->show();
}

// Unload the plugin by cleaning up the GUI
void tcpCock::unload()
{
  // remove the GUI
  mQGisIface->removePluginMenu("&tcpCock",mQActionPointer);
  mQGisIface->removeToolBarIcon(mQActionPointer);
  delete mQActionPointer;
}

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This code is also part of same file, but no problem are reported for connect in this slot.
I have very similar code aprt of same package giving no troubles. I don't know how to move forward in it. Please help

[jacek]

tcpcock.cpp:105: error: no matching function for call to 'tcpCock::connect(QgsMapCanvas*, const char [28], tcpCock* const, const char [25])'

Make sure you have proper #include directive for QgsMapCanvas in that file.