Qt自定义委托

Qt中的委托通常都是继承自QStyledItemDelegate或者QItemDelegate，二者的区别主要在于绘制方式，QStyledItemDelegate会使用当前样式绘制，并且能够使用qss，因此在在自定义委托时，一般使用 QStyledItemDelegate作为基类。除此之外，二者基本没有区别，写法和用法都一样。

继承 QStyledItemDelegate需要实现以下几个函数：

• createEditor()：returns the widget used to change data from the model and can be reimplemented to customize editing behavior.
• setEditorData()： provides the widget with data to manipulate.
•  updateEditorGeometry()：ensures that the editor is displayed correctly with respect to the item view.
• setModelData()：returns updated data to the model.

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

假设一个QTableView中，某一列的数据全是“选项一，选项二，选项三”中的任意一个选项，这种情况下就可以把这一列的代理设置成以QComboBox为基础的，每次修改数据时双击表格中的cell，出现下拉框来选择数据。详细代码如下：

nari_combodelegate.h

#ifndef NARI_COMBODELEGATE_H
#define NARI_COMBODELEGATE_H

class NARI_ComboDelegate : public QItemDelegate
{
    Q_OBJECT
public:
    NARI_ComboDelegate(const QStringList &items, QObject *parent = NULL);
    ~NARI_ComboDelegate();

    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 getItemStr();

private:
    QStringList m_ls_itemtext;
};

#endif // NARI_COMBODELEGATE_H

nari_combodelegate.cpp

#include "nari_combodelegate.h"

NARI_ComboDelegate::NARI_ComboDelegate(const QStringList &items, QObject *parent) :
    QItemDelegate(parent)
{
    m_ls_itemtext = items;
}

NARI_ComboDelegate::~NARI_ComboDelegate(){ }

QWidget *NARI_ComboDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QComboBox *editor = new QComboBox(parent);
    editor->addItems(m_ls_itemtext);
    editor->setEditable(false);
    return editor;
}

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

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

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

QStringList NARI_ComboDelegate::getItemStr()
{
    return m_ls_itemtext;
}

mainwindow.cpp

// ...
ui->tableView->setItemDelegateForColumn(0, new NARI_ComboDelegate(QStringList() << "Item1" << "Item2" << "Item3"));
// ...

其他委托示例

限制输入大小

nari_doubledelegate.h

#ifndef NARI_DOUBLEDELEGATE_H
#define NARI_DOUBLEDELEGATE_H

class NARI_DoubleDelegate : public QItemDelegate
{
    Q_OBJECT
public :
    NARI_DoubleDelegate(double minval, double maxval, QObject *parent = NULL);
    ~NARI_DoubleDelegate();

    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:
    double m_minval, m_maxval;
};

#endif // NARI_DOUBLEDELEGATE_H

nari_doubledelegate.cpp

#include "nari_doubledelegate.h"

NARI_DoubleDelegate::NARI_DoubleDelegate(double minval, double maxval, QObject *parent)
    : QItemDelegate(parent)
{
    m_minval = minval;
    m_maxval = maxval;
}

NARI_DoubleDelegate::~NARI_DoubleDelegate(){  }

QWidget *NARI_DoubleDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QDoubleSpinBox *editor = new QDoubleSpinBox(parent);
    editor->setToolTip(QString::number(m_minval) + " - " + QString::number(m_maxval));
    editor->setMinimum(m_minval);
    editor->setMaximum(m_maxval);
    return editor;
}

void NARI_DoubleDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    double value = index.model()->data(index, Qt::EditRole).toDouble();
    QDoubleSpinBox *spinBox = dynamic_cast<QDoubleSpinBox*>(editor);
    spinBox->setValue(value);
}

void NARI_DoubleDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    QDoubleSpinBox *spinBox = dynamic_cast<QDoubleSpinBox*>(editor);
    spinBox->interpretText();
    int value = spinBox->value();
    model->setData(index, value, Qt::EditRole);
}

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

限制输入IP地址

nari_Ipdelegate.h

#ifndef NARI_IPDELEGATE_H
#define NARI_IPDELEGATE_H

class NARI_IpDelegate : public QItemDelegate
{
public:
    NARI_IpDelegate(QObject *parent = NULL);
    ~NARI_IpDelegate();

    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;
};

#endif // NARI_IPDELEGATE_H

nari_Ipdelegate.cpp

#include "nari_ipdelegate.h"


NARI_IpDelegate::NARI_IpDelegate(QObject *parent)
    : QItemDelegate(parent)
{

}

NARI_IpDelegate::~NARI_IpDelegate(){ }

QWidget *NARI_IpDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QLineEdit *editor = new QLineEdit(parent);
    editor->setValidator(new QRegExpValidator(QRegExp("^((2[0-4]\\d|25[0-5]|[01]?\\d\\d?)\\.){3}(2[0-4]\\d|25[0-5]|[01]?\\d\\d?)$"), parent));
    editor->setInputMask("000.000.000.000;0");  //必须加;0否则前面的正则表达式失效，;0”表示删除时默认填充为0
    return editor;
}

void NARI_IpDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QString value = index.model()->data(index, Qt::EditRole).toString();
    QLineEdit *le = dynamic_cast<QLineEdit*>(editor);
    le->setText(value);
}

void NARI_IpDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    model->setData(index, dynamic_cast<QLineEdit*>(editor)->text(), Qt::EditRole);
}

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