[SOLVED] Widget plugin ... how to ?

[yellowmat]

Hi,

Here I am once again.

I'm trying to developp my own custom widget. I did it well the old fashion way but when I try to do it as a plugin it fails at compilation, invoking a problem with my Constructor, I don't know why so I hopre someone could help me.

The widget I'm trying to developp is a FileChooser from Qt Tutorial.

The compilation error message is the following :

error C2533 CustomWidgetPlugin::CustomWidgetPlugin : constructor not allowed a return type

... I'm pretty sure that it does not return any value, so why does the compilation failed ?

Here is my code for the .h

#include <qwidgetplugin.h>

class CustomWidgetPlugin : public QWidgetPlugin
{
public:
CustomWidgetPlugin();

QStringList keys() const;
QWidget* create(const QString& classname, QWidget* parent=0, const char* name=0);
QString group(const QString&) const;
QIconSet iconSet(const QString&) const;
QString includeFile(const QString&) const;
QString toolTip(const QString&) const;
QString whatsThis(const QString&) const;
bool isContainer(const QString&) const;
}

the code for the .cpp

#include "CustomWidgetPlugin.h"

CustomWidgetPlugin::CustomWidgetPlugin()
{

}

QStringList CustomWidgetPlugin::keys() const
{
QStringList list;
list << "FileChooser";
return list;
}

QWidget* CustomWidgetPlugin::create(const QString& key, QWidget* parent, const char* name) const
{
if( key == "FileChooser" )
return new FileChooser(parent, name);
return 0;
}

QString CustomWidgetPlugin::includeFile(const QString& feature) const
{
if( feature == "FileChooser" )
return "filechooser.h";
return QString::null;
}

QString CustomWidgetPlugin::group(const QString& feature) const
{
if( feature == "FileChooser" )
return "Input";
return QString::null;
}

QIconSet CustomWidgetPlugin::iconSet(const QString& feature) const
{
return QIconSet( QPixmap("filechooser_pixmap.png"));
}

QString CustomWidgetPlugin::toolTip(const QString& feature) const
{
if( feature == "FileChooser" )
return "File Chooser Widget";
return QString::null;
}

QString CustomWidgetPlugin::whatsThis(const QString& feature) const
{
if( feature == "FileChooser" )
return "A widget to choose a file";
return QString::null;
}

bool CustomWidgetPlugin::isContainer(const QString& feature) const
{
return FALSE;
}

Q_EXPORT_PLUGIN( CustomWidgetPlugin )

and my .pro

SOURCES += CustomWidgetPlugin.cpp ../FileChooser/filechooser.cpp
HEADERS += CustomWidgetPlugin.h ../FileChooser/filechooser.h
DESTDIR = $(QTDIR)/plugins/designer
TARGET = filechooser

target.path=$$plugins.path
isEmpty(target.path):target.path==$$QT_PREFIX/plugins
INSTALLS += target
TEMPLATE = lib
CONFIG += qt warn_on release plugin
INCLUDEPATH += $(QTDIR)/tools/designer/interfaces
DBFILE = CustomWidgetPlugin.db
PROJECTNAME = CustomWidgetPlugin
LANGUAGE = C++


Thanks in advance for your help.

[wysota]

I don't know if it is connected to the error you mention, but in the constructor the base class constructor should be called.

[yellowmat]

So, I changed my constructor implementation as follow:

CustomWidgetPlugin::CustomWidgetPlugin()
:QWidgetPlugin()
{
}

... but I still have the same problems, it does not compile. :confused:

It may be due to the way I'm trying to compile my sources, here is the method :
* I go in the folder where the sources are and type the two following commands :
qmake -o Makefile CustomWidgetPlugin.pro
nmake

Pfff, sometimes, developping getting on my nerves :mad:

[jacek]

Try adding a semicolon after the closing brace of your class definition.

[yellowmat]

Even if I had a semicolon it still does not compile and I have the same error messages.

I don't understand why it crashes, crual world.

The situation is locked for the moment. The custom widget FileChooser works, I am sure of this because I use it in an application. But how impossible it seems to be to integrate it in a plugin.

I hope someone will find out what's wrong with my code.

[jacek]

Try this way:
class QT_WIDGET_PLUGIN_EXPORT CustomWidgetPlugin : public QWidgetPlugin
{
// ...
};What is the first error you get?

[yellowmat]

So here is the code of my custom widget plugin
... the .h

#include <qwidgetplugin.h>

class QT_WIDGET_PLUGIN_EXPORT CustomWidgetPlugin : public QWidgetPlugin
{
public:
CustomWidgetPlugin();

QStringList keys() const;
QWidget* create(const QString& classname, QWidget* parent=0, const char* name=0);
QString group(const QString&) const;
QIconSet iconSet(const QString&) const;
QString includeFile(const QString&) const;
QString toolTip(const QString&) const;
QString whatsThis(const QString&) const;
bool isContainer(const QString&) const;
}

... and the .cpp

#include "CustomWidgetPlugin.h"

CustomWidgetPlugin::CustomWidgetPlugin()
:QWidgetPlugin()
{

}

QStringList CustomWidgetPlugin::keys() const
{
QStringList list;
list << "FileChooser";
return list;
}

QWidget* CustomWidgetPlugin::create(const QString& key, QWidget* parent, const char* name) const
{
if( key == "FileChooser" )
return new FileChooser(parent, name);
return null ;
}

QString CustomWidgetPlugin::includeFile(const QString& feature) const
{
if( feature == "FileChooser" )
return "filechooser.h";
return QString::null;
}

QString CustomWidgetPlugin::group(const QString& feature) const
{
if( feature == "FileChooser" )
return "Input";
return QString::null;
}

QIconSet CustomWidgetPlugin::iconSet(const QString& feature) const
{
return QIconSet( QPixmap("filechooser_pixmap.png"));
}

QString CustomWidgetPlugin::toolTip(const QString& feature) const
{
if( feature == "FileChooser" )
return "File Chooser Widget";
return QString::null;
}

QString CustomWidgetPlugin::whatsThis(const QString& feature) const
{
if( feature == "FileChooser" )
return "A widget to choose a file";
return QString::null;
}

bool CustomWidgetPlugin::isContainer(const QString& feature) const
{
return FALSE;
}

Q_EXPORT_PLUGIN( CustomWidgetPlugin )

and my .pro

################################################## ####################
# Automatically generated by qmake (1.07a) dim. 29. janv. 10:37:16 2006
################################################## ####################

SOURCES += CustomWidgetPlugin.cpp ../FileChooser/FileChooser.cpp
HEADERS += CustomWidgetPlugin.h ../FileChooser/FileChooser.h
DESTDIR = $(QTDIR)/plugins/designer
TARGET = filechooser

target.path = $$plugins.path
isEmpty(target.path):target.path==$$QT_PREFIX/plugins
INSTALLS += target
TEMPLATE = lib
CONFIG += qt warn_on release plugin
INCLUDEPATH += $(QTDIR)/tools/designer/interfaces
DBFILE = plugin.db
PROJECTNAME = Plugin
LANGUAGE = C++


So, I go to the folder where are those files I type in console mode the two following commands :

qmake -o Makefile CustomWidgetPlugin.pro

nmake

Then the console displays me the following errors :

.\CustomWidgetPlugin.cpp(4) : error C2533 : 'CustomWidgetPlugin::CustomWidgetPlugin' : constructors not allowed a retrun type


.\CustomWidgetPlugin.cpp(17) : error C2511 : 'create' : overloaded member function 'class QWidget*(const class QString&, class Widget*, const char*) const not found in CustomWidgetPlugin ./CustomWidgetPlugin.h(3) : see declaration of CustomWidgetPlugin

.\CustomWidgetPlugin.cpp(61) : error C2264 : 'CustomWidgetPlugin::CustomWidgetPlugin' : error in function definiton or declaration; function not called

That 's all information I can give you.

I hope you will be able to help me.

Thanks in advance.

[wysota]

Try adding #include <qwidget.h> to the header file. And a semicolon after class declaration. And Q_EXPORT_PLUGIN( ) macro.

[yellowmat]

Ok, that's what I did.

I alse add the following line in my plugin header

#include ".\\..\\FileChooser\\FileChooser.h"

I still have some errors, but different this time. Here they are :

.\CustomWidgetPlugin.cpp(62) : error C2259: 'CustomWidgetPlugin' : cannot instantiate abstract class due to following members : /.CustomWidgetPlugin.h(4) : see declaration of 'CustomWidgetPlugin'

The line 62 in this file points to the following :

Q_EXPORT_PLUGIN( CustomWidgetPlugin );

[jacek]

Remove "const" after CustomWidgetPlugin::create() in .cpp file.

[yellowmat]

Thanks Jacek because you lead me to the victory :) with your final advise.

I also thanks all other contributors without who I would not be able to realize my first plugin :)

Just in case if someone else try to make its own widget as a plugin, I write the full code :

FileChooser.h

// FileChooser.h: interface for the CFileChooser class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_FILECHOOSER_H__59B1F80E_2AB6_4FAD_BA4 D_DEAA892068B8__INCLUDED_)
#define AFX_FILECHOOSER_H__59B1F80E_2AB6_4FAD_BA4D_DEAA892 068B8__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <qwidget.h>

class QLineEdit;
class QPushButton;

class CFileChooser : public QWidget
{
Q_OBJECT
Q_PROPERTY( QString fileName READ fileName WRITE setFileName)
// Constructor / Destructor
public:
CFileChooser(QWidget* parent=0, const char* name=0);
virtual ~CFileChooser();

// Slots
public slots:
void setFileName( const QString& fn );

private slots:
void chooseFile();

// Signals
signals:
void fileNameChanged( const QString& fn );

// Functions
public:
QString fileName() const;

// Members
private:
QLineEdit* lineEdit;
QPushButton* button;
};

#endif // !defined(AFX_FILECHOOSER_H__59B1F80E_2AB6_4FAD_BA4 D_DEAA892068B8__INCLUDED_)


FileChooser.cpp

// FileChooser.cpp: implementation of the CFileChooser class.
//
//////////////////////////////////////////////////////////////////////

#include "FileChooser.h"
#include <qlayout.h>
#include <qlineedit.h>
#include <qpushbutton.h>
#include <qfiledialog.h>

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CFileChooser::CFileChooser(QWidget* parent, const char* name)
:QWidget(parent, name)
{
QHBoxLayout* layout = new QHBoxLayout(this);
layout->setMargin(0);

lineEdit = new QLineEdit(this, "filechooser_lineedit");
layout->addWidget(lineEdit);

connect(lineEdit, SIGNAL(textChanged(const QString&)), this, SIGNAL(fileNameChanged(const QString&)));

button = new QPushButton("...", this, "filechooser_button");
button->setFixedWidth(button->fontMetrics().width("..."));
layout->addWidget(button);

connect(button, SIGNAL(clicked()), this, SLOT(chooseFile()));

setFocusProxy(lineEdit);
}



CFileChooser::~CFileChooser()
{

}



void CFileChooser::setFileName(const QString& fn)
{
lineEdit->setText(fn);
}



QString CFileChooser::fileName() const
{
return lineEdit->text();
}



void CFileChooser::chooseFile()
{
QString fn;
fn = QFileDialog::getOpenFileName(lineEdit->text(), QString::null, this);

if( !fn.isEmpty() )
{
lineEdit->setText(fn);
emit fileNameChanged(fn);
}
}

Plugin.h

#include <qwidgetplugin.h>
#include <qwidget.h>

class QT_WIDGET_PLUGIN_EXPORT CustomWidgetPlugin : public QWidgetPlugin
{
public:
CustomWidgetPlugin();

QStringList keys() const;
QWidget* create(const QString& classname, QWidget* parent=0, const char* name=0);
QString group(const QString&) const;
QIconSet iconSet(const QString&) const;
QString includeFile(const QString&) const;
QString toolTip(const QString&) const;
QString whatsThis(const QString&) const;
bool isContainer(const QString&) const;
};

Plugin.cpp

#include "CustomWidgetPlugin.h"
#include ".\\..\\FileChooser\\FileChooser.h"

CustomWidgetPlugin::CustomWidgetPlugin()
:QWidgetPlugin()
{

}

QStringList CustomWidgetPlugin::keys() const
{
QStringList list;
list << "CFileChooser";
return list;
}

QWidget* CustomWidgetPlugin::create(const QString& key, QWidget* parent, const char* name)
{
if( key == "CFileChooser" )
return new CFileChooser(parent, name);
return 0;
}

QString CustomWidgetPlugin::includeFile(const QString& feature) const
{
if( feature == "CFileChooser" )
return "filechooser.h";
return QString::null;
}

QString CustomWidgetPlugin::group(const QString& feature) const
{
if( feature == "CFileChooser" )
return "Input";
return QString::null;
}

QIconSet CustomWidgetPlugin::iconSet(const QString& feature) const
{
return QIconSet( QPixmap("filechooser_pixmap.png"));
}

QString CustomWidgetPlugin::toolTip(const QString& feature) const
{
if( feature == "CFileChooser" )
return "File Chooser Widget";
return QString::null;
}

QString CustomWidgetPlugin::whatsThis(const QString& feature) const
{
if( feature == "CFileChooser" )
return "A widget to choose a file";
return QString::null;
}

bool CustomWidgetPlugin::isContainer(const QString& feature) const
{
return FALSE;
}

Q_EXPORT_PLUGIN( CustomWidgetPlugin );

Plugin.pro

################################################## ####################
# Automatically generated by qmake (1.07a) dim. 29. janv. 10:37:16 2006
################################################## ####################

SOURCES += CustomWidgetPlugin.cpp ../FileChooser/FileChooser.cpp
HEADERS += CustomWidgetPlugin.h ../FileChooser/FileChooser.h
DESTDIR = $(QTDIR)/plugins/designer
TARGET = filechooser

target.path = $$plugins.path
isEmpty(target.path):target.path==$$QT_PREFIX/plugins
INSTALLS += target
TEMPLATE = lib
CONFIG += qt warn_on release plugin
INCLUDEPATH += $(QTDIR)/tools/designer/interfaces
DBFILE = plugin.db
PROJECTNAME = Plugin
LANGUAGE = C++