how can i get Delegate for QTableWidget?

[srikanth]

Problem in getting delegates on QTableWidget, I'm trying to use two delegates (comboboxdelegate, spinbox delegate) to control user input in a QTableWidget with 2 columns and one row, but after reading the Delegate Classes page and looking through the SpinBox & comboox Delegate example, I thought I'd figured out how things work, but clearly haven't.

(sorry for my english), any help is appreciated.

The code is as follows.

notepad.h file

#ifndef NOTEPAD_H
#define NOTEPAD_H
#include <QtGui>

class Notepad : public QMainWindow
{
    Q_OBJECT

   public:
		//Notepad(QWidget *parent = 0, Qt::WFlags flags = 0);
		Notepad();
		void test();
		QTableWidget* table ;
    public slots:
        void add();
        void Delete();
		void mouseReleaseEvent ( QMouseEvent * event );

    private:
        QAction *add_action;
        QAction *Delete_action;
		
};

class SpinBoxDelegate : public QStyledItemDelegate,public Notepad
{
    Q_OBJECT
public:
    SpinBoxDelegate(QObject *parent = 0);
    QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option,
                          const QModelIndex &index) /*const Q_DECL_OVERRIDE*/;

    void setEditorData(QWidget *editor, const QModelIndex &index) /*const Q_DECL_OVERRIDE*/;
    void setModelData(QWidget *editor, QAbstractItemModel *model,
                      const QModelIndex &index) /*const Q_DECL_OVERRIDE*/;

    void updateEditorGeometry(QWidget *editor,
        const QStyleOptionViewItem &option, const QModelIndex &index) /*const Q_DECL_OVERRIDE*/;
};

class ComboBoxDelegate : public QStyledItemDelegate,public Notepad
{
Q_OBJECT

public:
ComboBoxDelegate(QObject *parent = 0);

QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option,
const QModelIndex &index) const;

void setEditorData(QWidget *editor, const QModelIndex &index) const;
void setModelData(QWidget *editor, QAbstractItemModel *model,
const QModelIndex &index) const;

void updateEditorGeometry(QWidget *editor,
const QStyleOptionViewItem &option, const QModelIndex &index) const;
};

#endif // NOTEPAD_H

notepad.cpp file

#include "notepad.h"
#include <QMessageBox>
#include <QTableView>
#include <QMouseEvent>
#include <QSpinBox>
#include <QComboBox>
#include <QStandardItemModel>
Notepad::Notepad()
{
	table = new QTableWidget();
	 test() ;
		SpinBoxDelegate();
		ComboBoxDelegate();
	add_action = new QAction(tr("Add cell"), this);
	add_action->setIcon(QIcon("add.jpg"));
    Delete_action = new QAction(tr("Delete cell"), this);
	Delete_action->setIcon(QIcon("delete.jpg"));
    
	connect(Delete_action, SIGNAL(triggered()), this, SLOT(Delete()));
	connect(add_action, SIGNAL(triggered()), this, SLOT(add()));
  	
	//tableItem->setFlags(tableItem->flags() ^ Qt::ItemIsEditable);
	
	centralWidget()->setAttribute(Qt::WA_TransparentForMouseEvents);
	centralWidget()->setAttribute(Qt::WA_MouseTracking,true);
	
	setMouseTracking(true);
	
}
void Notepad::test() 
{	    
	
	QTableWidgetItem* tableItem = new QTableWidgetItem();
	
	table->setRowCount(1);
	table->setColumnCount(3);
	table->setItem(0,0,new QTableWidgetItem());
	table->setItem(0,1,new QTableWidgetItem());
	table->setItem(0,2,new QTableWidgetItem());

	table->setMouseTracking(true);
    table->viewport()->setMouseTracking(true);
    table->installEventFilter(this);
    table->viewport()->installEventFilter(this);

	table->setSelectionBehavior(QAbstractItemView::SelectRows);
    table->setSelectionMode(QAbstractItemView::SingleSelection);
	
	QStandardItemModel model((table->rowCount()),(table->columnCount()));
	SpinBoxDelegate sdelegate;

	ComboBoxDelegate comDel;
	 for (int row = 0; row < 4; ++row)
	{
		QWidget *parent;
		QStyleOptionViewItem option;
        for (int column = 0; column < 1; ++column)
		{
			
			table->setItemDelegateForColumn( column, &comDel);
			QModelIndex index = model.index(row, column, QModelIndex());
            model.setData(index, QVariant((row + 1) * (column + 1)));
        }
		for (int column = 1; column < 2; ++column) 
		{
		
		table->setItemDelegateForColumn( column, &sdelegate  );
		QModelIndex index = model.index(row, column, QModelIndex());
        model.setData(index, QVariant((row + 1) * (column + 1)));
		}
	}




	table->setHorizontalHeaderItem(0, new QTableWidgetItem("combobox"));
	table->setHorizontalHeaderItem(1, new QTableWidgetItem("spinbox"));
	table->setHorizontalHeaderItem(2, new QTableWidgetItem("lineEdit"));
	tableItem->setFlags(tableItem->flags() ^ Qt::ItemIsEditable);
	table->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);
	setCentralWidget(table);
	
}

void Notepad::mouseReleaseEvent (QMouseEvent * event )
{	
	QMessageBox* msgBox;
	if(event->button() == Qt::RightButton)
	  {
QMouseEvent *mouseEvent = static_cast<QMouseEvent*> (event);
       QMenu *menu = new QMenu(this);
       menu->addAction(add_action);
       menu->addAction(Delete_action);
       menu->exec(mouseEvent->globalPos());
	   //msgBox->setInformativeText("u pressed right button");   	  	  
	} 
}
void Notepad::add() 
{
					
	table->insertRow( 1);
	
	setCentralWidget(table);
	centralWidget()->setAttribute(Qt::WA_TransparentForMouseEvents);
	setMouseTracking(true);
}
void Notepad::Delete() 
{
	
	table->removeRow(1);

	setCentralWidget(table);
	centralWidget()->setAttribute(Qt::WA_TransparentForMouseEvents);
    setMouseTracking(true);
}








SpinBoxDelegate::SpinBoxDelegate(QObject *parent)
    : QStyledItemDelegate(parent)
{
}
QWidget *SpinBoxDelegate::createEditor(QWidget *parent,
    const QStyleOptionViewItem &/* option */,
    const QModelIndex &/* index */)/* const*/
{

    QSpinBox *editor = new QSpinBox(parent);
    editor->setFrame(false);
    editor->setMinimum(0);
    editor->setMaximum(100);
    return editor;
}

void SpinBoxDelegate::setEditorData(QWidget *editor,
                                    const QModelIndex &index) /*const*/
{
    int value = index.model()->data(index, Qt::EditRole).toInt();
    QSpinBox *spinBox = static_cast<QSpinBox*>(editor);
    spinBox->setValue(value);
}

void SpinBoxDelegate::setModelData(QWidget *editor, QAbstractItemModel *model,
                                   const QModelIndex &index) /*const*/
{
    QSpinBox *spinBox = static_cast<QSpinBox*>(editor);
    spinBox->interpretText();
    int value = spinBox->value();
    model->setData(index, value, Qt::EditRole);
}

void SpinBoxDelegate::updateEditorGeometry(QWidget *editor,
    const QStyleOptionViewItem &option, const QModelIndex &/* index */) /*const*/
{
    editor->setGeometry(option.rect);
}

ComboBoxDelegate::ComboBoxDelegate(QObject *parent)
: QStyledItemDelegate(parent)
{
}

QWidget *ComboBoxDelegate::createEditor(QWidget *parent,
const QStyleOptionViewItem &/* option */,
const QModelIndex &/* index */) const
{
QComboBox *editor = new QComboBox(parent);
QStringList list ;
list << "srikanth" << "dilip";
editor->addItems(list);
//editor->installEventFilter(const_cast<ComboBoxDelegate*>(this));

return editor;
}

void ComboBoxDelegate::setEditorData(QWidget *editor,
const QModelIndex &index) const
{
QString value = index.model()->data(index, Qt::DisplayRole).toString();

QComboBox *comboBox = static_cast<QComboBox*>(editor);
comboBox->addItem(value);
}

void ComboBoxDelegate::setModelData(QWidget *editor, QAbstractItemModel *model,
const QModelIndex &index) const
{
QComboBox *comboBox = static_cast<QComboBox*>(editor);
QString value = comboBox->currentText();

model->setData(index, value);
}

void ComboBoxDelegate::updateEditorGeometry(QWidget *editor,
const QStyleOptionViewItem &option, const QModelIndex &/* index */) const
{
editor->setGeometry(option.rect);
}

main.cpp file

#include <QtGui>
#include <notepad.h>
int main(int argv, char **args)  {
    QApplication app(argv, args);
	
   Notepad notepad;
 
    notepad.show();

    return app.exec();
}

[mrjj]

Hi and welcome
in ::test()
you have
ComboBoxDelegate comDel;
This will be deleted as soon as Test ends. ( running out of scope)
So thats not so good as we want it to live longer :)

Please try
ComboBoxDelegate * comDel = new ComboBoxDelegate ();

for your delegates so they outlive the function where created.

[srikanth]

@mrjj ComboBoxDelegate comDel; and SpinBoxDelegate sdelegate;
are the class objects , am calling here to execute on those objects .

[mrjj]

@srikanth
But you set them to the view and
void Notepad::test()
{
..
ComboBoxDelegate comDel;; <<< lives here. not in class

Will die as soon as test() is executed and the view will point to invalid object.

here u give it address of this local variable that will be deleted soon.
table->setItemDelegateForColumn( column, &comDel);

So it does NOT look right to me :)

[srikanth]

@mrjj so what can i do ta add delegates , actually Notepad class is to create a window with tablewidget contains 3 columns and 1 row,am using mouse event to add rows and delete rows by using ActinEvent methods, up to here everything is doing good, now i am trying to add combobox delegate to 1st column and spinbox delegate to 2nd column so am not able to do please give me the solution please...

[mrjj]

@srikanth

you just new them instead :)
ComboBoxDelegate * comDel = new ComboBoxDelegate ();
Rest is 100% the same.
except no & in
table->setItemDelegateForColumn( column, &comDel);
-->
table->setItemDelegateForColumn( column, comDel);

[srikanth]

@mrjj but again same problem raising.

[VRonin]

@mrjj The view does not take ownership of the delegate so you have to give a parent to comDel or it will leak

[mrjj]

@VRonin
Thanks. I thought setItemDelegateForColumn would - so thats a very good point;
(Docs clearly states it do not so assumption is the mother of all fups :)

[mrjj]

@srikanth
Hi
You changed to use new?
So what is the exact issue?
No deletegate is shown, or ?

[srikanth]

@mrjj the error is showing like this "Unhandled exception at 0x778e3560 in add or remove colmns.exe:0xC00000FD:Stack overflow. "
and i make changes like this as you said

void Notepad::test() 
{	
	QTableWidgetItem* tableItem = new QTableWidgetItem();
	
	table->setRowCount(1);
	table->setColumnCount(3);
	table->setItem(0,0,new QTableWidgetItem());
	table->setItem(0,1,new QTableWidgetItem());
	table->setItem(0,2,new QTableWidgetItem());

	table->setMouseTracking(true);
    table->viewport()->setMouseTracking(true);
    table->installEventFilter(this);
    table->viewport()->installEventFilter(this);

    table->setSelectionBehavior(QAbstractItemView::SelectRows);
    table->setSelectionMode(QAbstractItemView::SingleSelection);
	
	QStandardItemModel model((table->rowCount()),(table->columnCount()));
	//SpinBoxDelegate sdelegate;
	SpinBoxDelegate *sdelegate = new SpinBoxDelegate ();
	ComboBoxDelegate * comDel = new ComboBoxDelegate ();
	//ComboBoxDelegate comDel;
	 for (int row = 0; row < 4; ++row)
	{
		QWidget *parent;
		QStyleOptionViewItem option;
        for (int column = 0; column < 1; ++column)
		{
			
			table->setItemDelegateForColumn( column, comDel);
			QModelIndex index = model.index(row, column, QModelIndex());
            model.setData(index, QVariant((row + 1) * (column + 1)));
        }
		for (int column = 1; column < 2; ++column) 
		{
		
		table->setItemDelegateForColumn( column, sdelegate  );
		QModelIndex index = model.index(row, column, QModelIndex());
        model.setData(index, QVariant((row + 1) * (column + 1)));
		}
	}


	table->setHorizontalHeaderItem(0, new QTableWidgetItem("combobox"));
	table->setHorizontalHeaderItem(1, new QTableWidgetItem("spinbox"));
	table->setHorizontalHeaderItem(2, new QTableWidgetItem("lineEdit"));
	tableItem->setFlags(tableItem->flags() ^ Qt::ItemIsEditable);
	table->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);
	setCentralWidget(table);
	
}

[mrjj]

Hi
That is a bug in your code, most likely.

Please use debugger and single step to find the line
that gives it.

Its very hard to guess by looking at code.

You get a Stack overflow - which often is a infinite loop or something like that.

[srikanth]

This post is deleted!

[srikanth]

@mrjj

am getting error like this am not able to find where the error is , please help me.

[mrjj]

@srikanth
Most likely in your delegate.
You can insert break point in each function and single step when you reach it.
That way you can find where it crashes.
No way i can just guess it, sadly.

if you think it crash in Notepad::test()
single step should find it.

[Jan-Willem]

Just wondering, but it seems you add a columnDelegate for every row you pass through. If I'm not mistaken, you should add a columnDelegate just once for the entire column.

And you seem to use a for-statement for setting the columDelegate, while you only execute it once. That doesn't make sense to me.

I'm not sure if this would fix anything of your problem, but I think you're code would benefit from it if you if you fixed this.

[srikanth]

@mrjj i did debug by using break points, everything is working fine , in .cpp file up to return app.exec(); in main.cpp , here it is getting crash and showing this error.

[srikanth]

@Jan-Willem thanks a lot the error is fix, when i put for loop in a comment , now how can i assign ComboBoxDelegate for 1st column and SpinBoxDelegate to 2nd cloumn.

[mrjj]

@srikanth
hi
Sounds like you crash when close down then/cleaning up.
I think
@Jan-Willem has a point of you setting multiple times.
setItemDelegateForColumn( column, comDel);
It might delete it multiple times.
So please try set only once. (for test)

[Jan-Willem]

In addidtion to @mrjj, I would suggest before or after the entire

for (int row = 0; row < 4; ++row)