Combo Boxes in Item Views: Difference between revisions

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=Combo Boxes in Item Views=
{{LangSwitch}}
[[Category:Snippets]]
Sample code to use combo boxes as editor widgets in an item view or item widget.
 
The delegate creates a combo box if the index is in the second column of a list view. For the other columns it just returns the default editor, that {{DocLink|QStyledItemDelegate}} creates.
 
File comboboxitemdelegate.h
 
  <nowiki>
#ifndef COMBOBOXITEMDELEGATE_H
#define COMBOBOXITEMDELEGATE_H
 
#include <QStyledItemDelegate>
 
class ComboBoxItemDelegate : public QStyledItemDelegate
{
    Q_OBJECT
public:
    ComboBoxItemDelegate(QObject *parent = nullptr);
    ~ComboBoxItemDelegate();
 
    QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
    void setEditorData(QWidget *editor, const QModelIndex &index) const override;
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override;
};
 
#endif // COMBOBOXITEMDELEGATE_H
  </nowiki>
 
File comboboxitemdelegate.cpp
 
  <nowiki>
#include "comboboxitemdelegate.h"
#include <QComboBox>
 
ComboBoxItemDelegate::ComboBoxItemDelegate(QObject *parent)
    : QStyledItemDelegate(parent)
{
}
 
 
ComboBoxItemDelegate::~ComboBoxItemDelegate()
{
}
 
 
QWidget *ComboBoxItemDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    // Create the combobox and populate it
    QComboBox *cb = new QComboBox(parent);
    const int row = index.row();
    cb->addItem(QString("one in row %1").arg(row));
    cb->addItem(QString("two in row %1").arg(row));
    cb->addItem(QString("three in row %1").arg(row));
    return cb;
}
 


Sample code to use combo boxes as editor widgets in an item view or item widget.
void ComboBoxItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QComboBox *cb = qobject_cast<QComboBox *>(editor);
    Q_ASSERT(cb);
    // get the index of the text in the combobox that matches the current value of the item
    const QString currentText = index.data(Qt::EditRole).toString();
    const int cbIndex = cb->findText(currentText);
    // if it is valid, adjust the combobox
    if (cbIndex >= 0)
      cb->setCurrentIndex(cbIndex);
}


The delegate creates a combo box if the index is in the second column of a list view. For the other columns it just returns the default editor, that [http://doc.qt.io/qt-5.0/qtwidgets/qstyleditemdelegate.html QStyledItemDelegate] ''[qt.io]'' creates.


File itemdelegate.h
void ComboBoxItemDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    QComboBox *cb = qobject_cast<QComboBox *>(editor);
    Q_ASSERT(cb);
    model->setData(index, cb->currentText(), Qt::EditRole);
}
  </nowiki>


File itemdelegate.cpp


File main.cpp
File main.cpp


===Categories:===
  <nowiki>
#include <QApplication>
#include <QTableWidget>
 
#include "comboboxitemdelegate.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QTableWidget tw;
 
    ComboBoxItemDelegate* cbid = new ComboBoxItemDelegate(&tw);
    // ComboBox only in column 2
    tw.setItemDelegateForColumn(1, cbid);
    tw.setColumnCount(4);
    tw.setRowCount(10);
    tw.resize(600,400);
    tw.show();


* [[:Category:snippets|snippets]]
    return a.exec();
}
  </nowiki>

Latest revision as of 20:31, 24 May 2021

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Sample code to use combo boxes as editor widgets in an item view or item widget.

The delegate creates a combo box if the index is in the second column of a list view. For the other columns it just returns the default editor, that QStyledItemDelegate creates.

File comboboxitemdelegate.h

 
#ifndef COMBOBOXITEMDELEGATE_H
#define COMBOBOXITEMDELEGATE_H

#include <QStyledItemDelegate>

class ComboBoxItemDelegate : public QStyledItemDelegate
{
    Q_OBJECT
public:
    ComboBoxItemDelegate(QObject *parent = nullptr);
    ~ComboBoxItemDelegate();

    QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
    void setEditorData(QWidget *editor, const QModelIndex &index) const override;
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override;
};

#endif // COMBOBOXITEMDELEGATE_H
  

File comboboxitemdelegate.cpp

 
#include "comboboxitemdelegate.h"
#include <QComboBox>

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


ComboBoxItemDelegate::~ComboBoxItemDelegate()
{
}


QWidget *ComboBoxItemDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    // Create the combobox and populate it
    QComboBox *cb = new QComboBox(parent);
    const int row = index.row();
    cb->addItem(QString("one in row %1").arg(row));
    cb->addItem(QString("two in row %1").arg(row));
    cb->addItem(QString("three in row %1").arg(row));
    return cb;
}


void ComboBoxItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QComboBox *cb = qobject_cast<QComboBox *>(editor);
    Q_ASSERT(cb);
    // get the index of the text in the combobox that matches the current value of the item
    const QString currentText = index.data(Qt::EditRole).toString();
    const int cbIndex = cb->findText(currentText);
    // if it is valid, adjust the combobox
    if (cbIndex >= 0)
       cb->setCurrentIndex(cbIndex);
}


void ComboBoxItemDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    QComboBox *cb = qobject_cast<QComboBox *>(editor);
    Q_ASSERT(cb);
    model->setData(index, cb->currentText(), Qt::EditRole);
}
  


File main.cpp

 
#include <QApplication>
#include <QTableWidget>

#include "comboboxitemdelegate.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QTableWidget tw;

    ComboBoxItemDelegate* cbid = new ComboBoxItemDelegate(&tw);
    // ComboBox only in column 2 
    tw.setItemDelegateForColumn(1, cbid);
    tw.setColumnCount(4);
    tw.setRowCount(10);
    tw.resize(600,400);
    tw.show();

    return a.exec();
}