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当打开 ComboBox 时，我的 ComboBox 填充了 CheckBox，第一个项目的委托 createEditor 未被调用，但是当您移至第二个项目时，它被调用并正确创建了委托。在此之后，当您移回第一项时，代表正在工作。问题仅在于第一次选择第一个项目。如果您在组合框中只有一个项目，则该项目是不可选择的。

这是我的代表的代码：

#include "checkboxlistdelegate.h"

CheckBoxListDelegate::CheckBoxListDelegate(QObject *parent)
  : QItemDelegate(parent) {
}

void CheckBoxListDelegate::paint(QPainter *painter,
                                 const QStyleOptionViewItem &option,
                                 const QModelIndex &index) const {
  //Get item data
  bool value = index.data(Qt::UserRole).toBool();
  QString text = index.data(Qt::DisplayRole).toString();
  // fill style options with item data
  const QStyle *style = QApplication::style();
  QStyleOptionButton opt;
  opt.state |= value ? QStyle::State_On : QStyle::State_Off;
  opt.state |= QStyle::State_Enabled;
  opt.text = text;
  opt.rect = option.rect;
  opt.palette = QPalette(Qt::white);
  // draw item data as CheckBox
  style->drawControl(QStyle::CE_CheckBox,&opt,painter);
}

QWidget* CheckBoxListDelegate::createEditor(QWidget *parent,
                                        const QStyleOptionViewItem& option,
                                        const QModelIndex & index ) const {
  QCheckBox *editor = new QCheckBox(parent);
  editor->setStyleSheet("QCheckBox {background-color: #aaaaaa; color: white;}");
  return editor;
}

void CheckBoxListDelegate::setEditorData(QWidget *editor,
                                         const QModelIndex &index) const {
  QCheckBox *myEditor = static_cast<QCheckBox*>(editor);
  myEditor->setText(index.data(Qt::DisplayRole).toString());
  myEditor->setChecked(index.data(Qt::UserRole).toBool());
}

void CheckBoxListDelegate::setModelData(QWidget *editor,
                                        QAbstractItemModel *model,
                                        const QModelIndex &index) const {
  //get the value from the editor (CheckBox)
  QCheckBox *myEditor = static_cast<QCheckBox*>(editor);
  bool value = myEditor->isChecked();
  //set model data
  QMap<int,QVariant> data;
  data.insert(Qt::DisplayRole,myEditor->text());
  data.insert(Qt::UserRole,value);
  model->setItemData(index,data);
  emit indexChanged(index);
}

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

这是我的 QComboBox 子类的代码：

CheckBoxList::CheckBoxList(QWidget *widget)
  : QComboBox(widget),title(""),selection() {
  // set delegate items view
  view()->setItemDelegate(new CheckBoxListDelegate(this));
  view()->setStyleSheet("QAbstractItemView {background-color:white;}");
  // Enable editing on items view
  view()->setEditTriggers(QAbstractItemView::AllEditTriggers);
  connect(view()->model(), SIGNAL(dataChanged(QModelIndex,QModelIndex)),
          this, SLOT(onItemClicked(QModelIndex)));
}

void CheckBoxList::paintEvent(QPaintEvent *) {
  QStylePainter painter(this);
  painter.setPen(palette().color(QPalette::Text));
  QStyleOptionComboBox opt;
  initStyleOption(&opt);
  opt.currentText = title;
  painter.drawComplexControl(QStyle::CC_ComboBox, opt);
  painter.drawControl(QStyle::CE_ComboBoxLabel, opt);
}

void CheckBoxList::setDisplayText(QString text) {
  title = text;
}

QString CheckBoxList::getDisplayText() const {
  return title;
}

bool CheckBoxList::isChecked(const QModelIndex& index) const {
  return view()->model()->itemData(index).value(Qt::UserRole).toBool();
}

谢谢你。

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