Widget copy problem

[Xentrum]

Hello,
In my application, i need to get one widget from a QList and add it into a layout. So i have : @layout->addWidget(myList.at(i));@ .

After modifiying my code in
@layout->addWidget(new QLabel(myList.at(i).text()));@

i've got some critical error : @In file included from ....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qobject.h:50,
from ....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qabstractanimation.h:45,
from ....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/QtCore:3,
from ....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/QtGui:3,
from ..\CSS_Explicit/mainwidget.h:4,
from ..\CSS_Explicit\mainwidget.cpp:1:
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtGui/qlineedit.h: In member function 'void QList<T>::node_construct(QList<T>::Node*, const T&) [with T = QLineEdit]':
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:512: instantiated from 'void QList<T>::append(const T&) [with T = QLineEdit]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:334: instantiated from 'QList<T>& QList<T>::operator<<(const T&) [with T = QLineEdit]'
..\CSS_Explicit\mainwidget.cpp:11: instantiated from here
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtGui/qlineedit.h:279: error: 'QLineEdit::QLineEdit(const QLineEdit&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:372: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtGui/qlineedit.h:279: error: 'QLineEdit::QLineEdit(const QLineEdit&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:373: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtGui/qlineedit.h:279: error: 'QLineEdit& QLineEdit::operator=(const QLineEdit&)' is private@

[Xentrum]

@....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:378: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qlabel.h: In member function 'void QList<T>::node_construct(QList<T>::Node*, const T&) [with T = QLabel]':
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:512: instantiated from 'void QList<T>::append(const T&) [with T = QLabel]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:334: instantiated from 'QList<T>& QList<T>::operator<<(const T&) [with T = QLabel]'
..\CSS_Explicit\mainwidget.cpp:13: instantiated from here
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qlabel.h:165: error: 'QLabel::QLabel(const QLabel&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:372: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qlabel.h:165: error: 'QLabel::QLabel(const QLabel&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:373: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qlabel.h:165: error: 'QLabel& QLabel::operator=(const QLabel&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:378: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtGui/qlineedit.h: In member function 'void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = QLineEdit]':
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:681: instantiated from 'QList<T>::Node* QList<T>::detach_helper_grow(int, int) [with T = QLineEdit]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:510: instantiated from 'void QList<T>::append(const T&) [with T = QLineEdit]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:334: instantiated from 'QList<T>& QList<T>::operator<<(const T&) [with T = QLineEdit]'
..\CSS_Explicit\mainwidget.cpp:11: instantiated from here
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtGui/qlineedit.h:279: error: 'QLineEdit::QLineEdit(const QLineEdit&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:399: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtGui/qlineedit.h:279: error: 'QLineEdit::QLineEdit(const QLineEdit&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:412: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qlabel.h: In member function 'void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = QLabel]':
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:681: instantiated from 'QList<T>::Node* QList<T>::detach_helper_grow(int, int) [with T = QLabel]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:510: instantiated from 'void QList<T>::append(const T&) [with T = QLabel]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:334: instantiated from 'QList<T>& QList<T>::operator<<(const T&) [with T = QLabel]'
..\CSS_Explicit\mainwidget.cpp:13: instantiated from here
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qlabel.h:165: error: 'QLabel::QLabel(const QLabel&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:399: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qlabel.h:165: error: 'QLabel::QLabel(const QLabel&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:412: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qboxlayout.h: In member function 'void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = QHBoxLayout]':
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:711: instantiated from 'void QList<T>::detach_helper(int) [with T = QHBoxLayout]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:725: instantiated from 'void QList<T>::detach_helper() [with T = QHBoxLayout]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:446: instantiated from 'QList<T>& QList<T>::operator=(const QList<T>&) [with T = QHBoxLayout]'
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:766: instantiated from 'void QList<T>::clear() [with T = QHBoxLayout]'
..\CSS_Explicit\mainwidget.cpp:15: instantiated from here
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qboxlayout.h:146: error: 'QHBoxLayout::QHBoxLayout(const QHBoxLayout&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:399: error: within this context
....\Qt\Desktop\Qt\4.8.1\mingw\include\QtGui/qboxlayout.h:146: error: 'QHBoxLayout::QHBoxLayout(const QHBoxLayout&)' is private
....\Qt\Desktop\Qt\4.8.1\mingw\include/QtCore/qlist.h:412: error: within this context
mingw32-make.exe[1]: *** [debug/mainwidget.o] Error 1
mingw32-make.exe: *** [debug] Error 2@

All of those errors are in qt files and i can't copy/add widget to another widget !

I need help !
Thanks.
Xentrum

[dbzhang800]

[quote author="Xentrum" date="1339606742"]Hello,
In my application, i need to get one widget from a QList and add it into a layout. So i have : @layout->addWidget(myList.at(i));@ .

After modifiying my code in
@layout->addWidget(new QLabel(myList.at(i).text()));@

[/quote]
Yes, If I am right, what you want it is
@layout->addWidget(new QLabel(myList.at(i)->text()));@

[Xentrum]

Yes. Principal error is about copying the widget : the overloaded constructor for copying QLabel/QLineEdit... Is suggested by Qt Creator but the debbuger says that this constructor is private

[Eddy]

This "link":http://qt-project.org/doc/qt-4.8/object.html#identity-vs-value can help understanding why.

[mlong]

Copying QWidgets is inherently prohibited. (What is a "copy" of a widget supposed to include?)

What is the purpose of your list of widgets? Would you be better off keeping a list of widget pointers?

That way you could work without having to make copies of the widgets themselves.

[Xentrum]

I want to do dynamics lines with 2 QLineEdit and 1 Label. The number of lines depend of the size of my QList which is the same as two other QList. Each list contains one widget(QLineEdit/Qlabel) and i'm doing "for" loop for creating my layout :
@for(int i = 0;i <= propertyList.size();i++){
QHBoxLayout *layoutExample = new QHBoxLayout();
layoutExample->addWidget(new QLabel(labelList.at(i).text()));
layoutExample->addWidget(new QLineEdit(propertyList.at(i).text()));
layoutExample->addWidget(new QLineEdit(valueList.at(i).text()));
layout->addLayout(layoutExample);
}@

EDIT : I just recompiled my codes and even when i've deleted this part the pb stay. Maybe should i repair my Qt installation ?

[mlong]

So what types are the QLists of? Where do they come from? Is it sufficient for the QLists to just contain QString values for the text, rather than widgets?

[Edit to add:]

You might also consider creating a custom widget class which contains your Label and TextEntry fields. Might make things a little tidier in working with things. (Just a suggestion, though.)

[Xentrum]

this is already a new widget. here's my complete code :
mainwidget.h:
@#ifndef MAINWIDGET_H
#define MAINWIDGET_H

#include <QtGui>

class MainWidget : public QWidget
{
Q_OBJECT
public:
explicit MainWidget(QWidget *parent = 0);
MainWidget(QString name);

signals:

public slots:

private:
QVBoxLayout *layout;
QString tabName;
QList<QLineEdit> propertyList;
QList<QLineEdit> valueList;
QList<QLabel> labelList;
QList<QHBoxLayout> *linePropertyList;
};

#endif // MAINWIDGET_H
@

and mainwidget.cpp :

@
#include "mainwidget.h"

MainWidget::MainWidget(QWidget *parent) :
QWidget(parent)
{
linePropertyList = new QList<QHBoxLayout>;
QHBoxLayout *mainlayout = new QHBoxLayout;
QString tabName = "New";
layout = new QVBoxLayout;
if(propertyList.isEmpty()){
propertyList <<QLineEdit("color");
valueList << QLineEdit("black");
labelList << QLabel(tr("Property 1"));
}
linePropertyList->clear();
for(int i = 0;i <= propertyList.size();i++){
QHBoxLayout *layoutExample = new QHBoxLayout();
layoutExample->addWidget(new QLabel(labelList.at(i).text()));
layoutExample->addWidget(new QLineEdit(propertyList.at(i).text()));
layoutExample->addWidget(new QLineEdit(valueList.at(i).text()));
layout->addLayout(layoutExample);
}
mainlayout->addLayout(layout);
mainlayout->addWidget(new QTextEdit());
setLayout(mainlayout);
}
MainWidget::MainWidget(QString name)
{
QHBoxLayout *mainlayout = new QHBoxLayout;
QString tabName = name;
layout = new QVBoxLayout;
mainlayout->addLayout(layout);
mainlayout->addWidget(new QTextEdit());
setLayout(mainlayout);
setMinimumSize(400,800);
}
@

[mlong]

Again, I ask...

Why are your lists of widgets, instead of QStrings? You only appear to be using the text values of those widgets in the lists.

Why not:
@
...
QList<QString> propertyList; // Or QStringList propertyList;
QList<QString> valueList;
QList<QString> labelList;
...
if(propertyList.isEmpty()){
propertyList <<"color";
valueList << "black";
labelList << tr("Property 1");
}
...
for(int i = 0;i <= propertyList.size();i++){
QHBoxLayout *layoutExample = new QHBoxLayout();
layoutExample->addWidget(new QLabel(labelList.at(i)));
layoutExample->addWidget(new QLineEdit(propertyList.at(i)));
layoutExample->addWidget(new QLineEdit(valueList.at(i)));
layout->addLayout(layoutExample);
}
...
@

[Xentrum]

i tried to directly create my object in a QList. But maybe your solution is better. I'll try it. Thanks

[Xentrum]

Now, i got another pb : because we are in a for loop, no layout is showed at the end. Do you have a solution ?

EDIT : In fact, there was no pb : i just forget to copy the code in my overloaded constructor