Custom Delegate

Hello all again!
I am stucked and need little help. I have QTableView and Costum Delegate for tableView's second column.
I think best way to express my problem is to show screenshots and source code:
mainwindow.cpp

Code:

---

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "cdelegate.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    model = new QStandardItemModel;
    for(int r = 0; r < 10; ++r){
        QStandardItem *item = new QStandardItem("Item " + QString::number(r));
        model->setItem(r,0,item);
        model->setItem(r,1,new QStandardItem("Qt is cool"));
    }
 
    ui->tableView->setModel(model);
    CDelegate *cdelegate = new CDelegate;
    ui->tableView->setItemDelegateForColumn(1,cdelegate);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}

---

cdelegate.h

Code:

---

#ifndef CDELEGATE_H
#define CDELEGATE_H
#include <QAbstractItemDelegate>
 
class CDelegate : public QAbstractItemDelegate
{
public:
    CDelegate();
 
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const;
    QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const;
 
 
    //I think this method would help to my problem
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const;
};
 
#endif // CDELEGATE_H

---

and cdelegate.cpp

Code:

---

#include "cdelegate.h"
#include <QPainter>
#include <QTableView>
 
CDelegate::CDelegate()
{
}
QSize CDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    return QSize(45,30);
}
void CDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if(index.row()%2 == 0){
        painter->setBrush(QColor(239,239,239));
        painter->fillRect(option.rect,painter->brush());
    }
}
void CDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    //...
}

---

So,result is this:
Attachment 10070

This is a problem:
I achieved what I wanted BUT the text: "Qt is cool" isn't appeared in the second column,for every row.
I tried many solution but without any result.


Have any idea? :)

The reason why you're text isn't appeared is obvious: You are reimplementing QAbstractItemDelegate::paint. Your reimplementation doesn't paint any text (only a filled rectangle).

To achieve a background color to be painted I suggest subclassing QAbstractItemModel or QAbstractTableModel. When implementing the data method, you can return the desired background color (as QBrush) for Qt::BackgroundRole.
You can also subclass QStyledItemDelegate and overwrite the initStyleOption method to set the desired background color.

Quote:

---

Originally Posted by Higgs

Have any idea? :)

---

Have you tried calling the base class implementation of paint()?

Quote:

---

Originally Posted by anda_skoa

Have you tried calling the base class implementation of paint()?

---

Quote:

---

Originally Posted by Infinity

The reason why you're text isn't appeared is obvious: You are reimplementing QAbstractItemDelegate::paint. Your reimplementation doesn't paint any text (only a filled rectangle).

To achieve a background color to be painted I suggest subclassing QAbstractItemModel or QAbstractTableModel. When implementing the data method, you can return the desired background color (as QBrush) for Qt::BackgroundRole.
You can also subclass QStyledItemDelegate and overwrite the initStyleOption method to set the desired background color.

---

Thank you both. I did subclass QStyleItemDelegate and overwrite paint method,then I called base class implementation of paint in overwritten method. that works.

That is a code:

Code:

---

#include "cdelegate.h"
#include <QPainter>
#include <QTableView>
CDelegate::CDelegate()
{
}
void CDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if(index.row()%2 == 0){
        painter->setBrush(QColor(239,239,239));
        painter->fillRect(option.rect,painter->brush());
        QStyledItemDelegate::paint(painter,option,index);
    }else
        QStyledItemDelegate::paint(painter,option,index);
}

---

Attachment 10071

When I Subclass QAbstractItemDelegate and then call base class implementation of paint,compiler gives me an error :)



And last question in this thread,In documentation I read that QItemDelegate and QStyledItem Delegates is default for all Item view. But in reallity which one is default delegate for all item view?

QStyledItemDelegate. It has taken over the job of being the default delegate, i.e. it is newer than QItemDelegate.

The Qt documentation says this: "Note that QStyledItemDelegate has taken over the job of drawing Qt's item views. We recommend the use of QStyledItemDelegate when creating new delegates."

Cheers,
_