I have been re-writing this project from the bottom up to "correctly" use the Model/View framework. I have a database with several tables. I have set up two views in a QMainWindow, along with a QSqlTableModel for each table I need, and when I need, I just swap a view to a different model and reconfigure columns, etc. That is all working out nicely. I have also managed to subclass QStyledItem to create a combobox to present a list of text entries, display the chosen text entry in the cell, but store its corresponding "id" number in the backend table/database.

I am now attempting to set up some columns with QCheckBox for boolean values, and I am close, but not quite there.

Here's what I have.

cbitemdelegate.h

Qt Code: 
  1. #ifndef CBITEMDELEGATE_H
  2. #define CBITEMDELEGATE_H
  3.  
  4. #include <QItemDelegate>
  5.  
  6. class CBItemDelegate : public QItemDelegate
  7. {
  8.     Q_OBJECT
  9. public:
  10.     explicit CBItemDelegate(QObject *parent = 0);
  11.     QWidget *createEditor(QWidget *parent,
  12.                           const QStyleOptionViewItem &option,
  13.                           const QModelIndex &index) const;
  14.     void setEditorData(QWidget *editor,
  15.                        const QModelIndex &index) const;
  16.     void setModelData(QWidget *editor,
  18.                       const QModelIndex &index) const;
  19.     void updateEditorGeometry(QWidget *editor,
  20.                               const QStyleOptionViewItem &option,
  21.                               const QModelIndex &index) const;
  22.     void paint(QPainter *painter,
  23.                const QStyleOptionViewItem &option,
  24.                const QModelIndex &index) const;
  25. };
  26.  
  27. #endif //CBITEMDELEGATE_H
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cbitemdelegate.cpp

Qt Code: 
  1. #include "cbitemdelegate.h"
  2. #include <QApplication>
  3. #include <QtGui>
  4.  
  5. CBItemDelegate::CBItemDelegate(QObject *parent)
  6. : QItemDelegate(parent)
  7. {
  8. }
  9.  
  10. QWidget *CBItemDelegate::createEditor(QWidget *parent,
  11.                                       const QStyleOptionViewItem &option,
  12.                                       const QModelIndex &index) const {
  13.     QCheckBox *editor = new QCheckBox(parent);
  14.     editor->installEventFilter(const_cast<CBItemDelegate*>(this));
  15.     return editor;
  16. }
  17.  
  18. void CBItemDelegate::setEditorData(QWidget *editor,
  19.                                    const QModelIndex &index) const {
  20.     int value = index.model()->data(index, Qt::DisplayRole).toInt();
  21.  
  22.     QCheckBox *checkBox = static_cast<QCheckBox*>(editor);
  23.     if(value == 1)
  24.         checkBox->setCheckState(Qt::Checked);
  25.     else
  26.         checkBox->setCheckState(Qt::Unchecked);
  27. }
  28.  
  29. void CBItemDelegate::setModelData(QWidget *editor,
  31.                                   const QModelIndex &index) const {
  32.     QCheckBox *checkBox = static_cast<QCheckBox*>(editor);
  33.     int value;
  34.     if(checkBox->checkState() == Qt::Checked)
  35.         value = 1;
  36.     else
  37.         value = 0;
  38.  
  39.     model->setData(index, value);
  40. }
  41.  
  42. void CBItemDelegate::updateEditorGeometry(QWidget *editor,
  43.                                           const QStyleOptionViewItem &option,
  44.                                           const QModelIndex &index) const {
  45.     editor->setGeometry(option.rect);
  46. }
  47.  
  48. void CBItemDelegate::paint(QPainter *painter,
  49.                            const QStyleOptionViewItem &option,
  50.                            const QModelIndex &index) const {
  51.     bool data = index.model()->data(index, Qt::DisplayRole).toBool();
  52.     QStyleOptionButton checkboxstyle;
  53.     QRect checkbox_rect = QApplication::style()->subElementRect(QStyle::SE_CheckBoxIndicator, &checkboxstyle);
  54.     checkboxstyle.rect = option.rect;
  55.     checkboxstyle.rect.setLeft(option.rect.x() + option.rect.width()/2 - checkbox_rect.width()/2);
  56.     if(data)
  57.         checkboxstyle.state = QStyle::State_On|QStyle::State_Enabled;
  58.     else
  59.         checkboxstyle.state = QStyle::State_Off|QStyle::State_Enabled;
  60.  
  61.     QApplication::style()->drawControl(QStyle::CE_CheckBox, &checkboxstyle, painter);
  62. }
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I then create an instance to a CBItemDelegate, and use setItemDelegateForColumn to install it to the view.

When I first bring the table up, it looks wonderful, all of the checkboxes are checked/unchecked appropriately, and they are all centered horizontally and vertically in their cells, thanks to the paint procedure.

Then when I click to edit the cells things start to go wrong. The checkbox jumps to the side of the cell, it responds, it is just on the side. I presume it is because in the createEditor function I am creating an actual QCheckBox with its attached (blank) QLabel, and that throws things off. Could somebody please help me past this point?