dataChanged 信号不适用于 ComboBoxDelegate

Question

我的问题如下：

有一个QTableView和一个QStandardItemModel这样使用：

ui->tableView->setModel(model);
model->setItem(myrow, mycolumn, myQStandardItem);

和一个组合框委托：

ComboBoxDelegate* mydelegate = new ComboBoxDelegate();
ui->tableView->setItemDelegateForColumn(mycolumn,mydelegate);

每次 table 的单元格的值被更改（通过组合框）我需要捕获新值和单元格的索引只是 modified.I 我正在使用信号 dataChaged 以这种方式关联到模型：

connect(model,SIGNAL(dataChanged(QModelIndex&,QModelIndex&)),this,SLOT(GetChangedValue(QModelIndex&)));

但它不起作用，它从不调用方法 GetChangedValue 尽管组合框已更改其值。我是否跳过了任何步骤？

下面是ComboBoxDelegate的代码：

class ComboBoxDelegate : public QStyledItemDelegate
{
    Q_OBJECT
public:

    ComboBoxDelegate(QVector<QString>& ItemsToCopy,QObject *parent = 0);
    ~ComboBoxDelegate();
     void setItemData(QVector<QString>& ItemsToCopy);

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



    private:
     QVector<QString> Items;

};

ComboBoxDelegate::ComboBoxDelegate(QVector<QString>&  ItemsToCopy,QObject  *parent)
:QStyledItemDelegate(parent)
{
    setItemData(ItemsToCopy);
}


ComboBoxDelegate::~ComboBoxDelegate()
{
}


QWidget *ComboBoxDelegate::createEditor(QWidget *parent, const     QStyleOptionViewItem &option, const QModelIndex &index) const
{

    QComboBox* editor = new QComboBox(parent);
    editor->setEditable(true);



    for (int i = 0; i < Items.size(); ++i)
    {
        editor->addItem(Items[i]);
    }


    editor->setStyleSheet("combobox-popup: 0;");

    return editor;
}




void ComboBoxDelegate::setEditorData(QWidget *editor, const QModelIndex  &index) const
{
    QComboBox *comboBox = static_cast<QComboBox*>(editor);
    QString currentText = index.data(Qt::EditRole).toString();
    int cbIndex = comboBox->findText(currentText);
    comboBox->setCurrentIndex(cbIndex);
}



void ComboBoxDelegate::setModelData(QWidget *editor, QAbstractItemModel    *model, const QModelIndex &index) const
 {
    QComboBox *comboBox = static_cast<QComboBox*>(editor);
    model->setData(index, comboBox->currentText(), Qt::EditRole);

}



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

}



void ComboBoxDelegate::setItemData(QVector<QString>&  ItemsToCopy)
{
    for (int row = 0; row < ItemsToCopy.size(); ++row)
    {

       Items.push_back(ItemsToCopy[row]);


   }

}

Answer 1

您的委托实现的问题是当组合索引更改时您没有发出 commitData 信号。它在 Qt 文档中有说明：

This signal must be emitted when the editor widget has completed editing the data, and wants to write it back into the model.

您可以将组合框作为委托 class 的成员，并将组合框的 currentIndexChanged 信号连接到发出 commitData 的某个插槽：

#include <QItemDelegate>

#include <QComboBox>

class ComboBoxDelegate: public QItemDelegate
{
 Q_OBJECT
public:
    ComboBoxDelegate(QObject *parent = 0);

    QWidget *createEditor( QWidget *parent,
                            const QStyleOptionViewItem &option,
                            const QModelIndex &index ) const;

    void setEditorData( QWidget *editor,
                            const QModelIndex &index ) const;

    void setModelData( QWidget *editor,
                            QAbstractItemModel *model,
                            const QModelIndex &index ) const;

    void updateEditorGeometry( QWidget *editor,
                            const QStyleOptionViewItem &option,
                            const QModelIndex &index ) const;

    QStringList comboItems;

    mutable QComboBox *combo;

private slots:

    void setData(int val);

};

ComboBoxDelegate::ComboBoxDelegate(QObject *parent ):QItemDelegate(parent)
{
        comboItems<<"Item 1"<<"Item 2"<<"Item 3";
}

QWidget *ComboBoxDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    combo = new QComboBox( parent );
    QObject::connect(combo,SIGNAL(currentIndexChanged(int)),this,SLOT(setData(int)));
    combo->addItems(comboItems);
    combo->setMaxVisibleItems(comboItems.count());
    return combo;
}

void ComboBoxDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QString text = index.model()->data( index, Qt::DisplayRole ).toString();

    int comboIndex = comboItems.indexOf(QRegExp(text));

    if(comboIndex>=0)
        (static_cast<QComboBox*>( editor ))->setCurrentIndex(comboIndex);
}

void ComboBoxDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    model->setData( index, static_cast<QComboBox*>( editor )->currentText() );
}


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

void ComboBoxDelegate::setData(int val)
{
    emit commitData(combo);
    //emit closeEditor(combo);
}

如您所见，组合框的 currentIndexChanged 信号连接到 setData 插槽，后者将数据提交给模型。此外，您应该将组合框声明为可变的，以便在 createEditor 中更新它，这是不变的。如果数据成员被声明为可变的，那么从 const 成员函数中为该数据成员赋值是合法的。

现在当组合框的索引改变时，dataChanged信号会被发射。

dataChanged 信号不适用于 ComboBoxDelegate

dataChanged signal does not work with ComboBoxDelegate

c++

qt

combobox

qtableview

qstyleditemdelegate