Custom Delegate

[Higgs]

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

#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;
}

#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;
}

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cdelegate.h

#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

#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

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and cdelegate.cpp

#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
{
    //...
}

#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
{
    //...
}

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So,result is this:
Capture.JPG

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?

[Infinity]

The reason why you're text isn't appeared is obvious: You are reimplementing QAbstractItemDelegate:aint. 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.

[anda_skoa]

Have any idea?

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

[Higgs]

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

The reason why you're text isn't appeared is obvious: You are reimplementing QAbstractItemDelegate:aint. 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:

#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);
}

#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);
}

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Capture.JPG

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?

[anda_skoa]

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,
_