简述

上节分享了使用自定义模型QAbstractTableModel来实现复选框。下面我们来介绍另外一种方式：
自定义委托-QAbstractItemDelegate。

效果

QAbstractTableModel

源码

table_model.cpp

#define CHECK_BOX_COLUMN 0
#define File_PATH_COLUMN 1

TableModel::TableModel(QObject *parent)
    : QAbstractTableModel(parent)
{

}

TableModel::~TableModel()
{

}

// 更新表格数据
void TableModel::updateData(QList<FileRecord> recordList)
{
    m_recordList = recordList;
    beginResetModel();
    endResetModel();
}

// 行数
int TableModel::rowCount(const QModelIndex &parent) const
{
    return m_recordList.count();
}

// 列数
int TableModel::columnCount(const QModelIndex &parent) const
{
    return 2;
}

// 设置表格项数据
bool TableModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    if (!index.isValid())
        return false;

    int nColumn = index.column();
    FileRecord record = m_recordList.at(index.row());
    switch (role)
    {
    case Qt::DisplayRole:
    {
        if (nColumn == File_PATH_COLUMN)
        {
            record.strFilePath = value.toString();

            m_recordList.replace(index.row(), record);
            emit dataChanged(index, index);
            return true;
        }
    }
    case Qt::CheckStateRole:
    case Qt::UserRole:
    {
        if (nColumn == CHECK_BOX_COLUMN)
        {
            record.bChecked = value.toBool();

            m_recordList.replace(index.row(), record);
            emit dataChanged(index, index);
            return true;
        }
    }
    default:
        return false;
    }
    return false;
}

// 表格项数据
QVariant TableModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

    int nRow = index.row();
    int nColumn = index.column();
    FileRecord record = m_recordList.at(nRow);

    switch (role)
    {
    case Qt::TextColorRole:
        return QColor(Qt::white);
    case Qt::TextAlignmentRole:
        return QVariant(Qt::AlignLeft | Qt::AlignVCenter);
    case Qt::DisplayRole:
    {
        if (nColumn == File_PATH_COLUMN)
            return record.strFilePath;
        return "";
    }
    case Qt::UserRole:
    {
        if (nColumn == CHECK_BOX_COLUMN)
            return record.bChecked;
    }
    default:
        return QVariant();
    }

    return QVariant();
}

// 表头数据
QVariant TableModel::headerData(int section, Qt::Orientation orientation, int role) const
{
    switch (role)
    {
    case Qt::TextAlignmentRole:
        return QVariant(Qt::AlignLeft | Qt::AlignVCenter);
    case Qt::DisplayRole:
    {
        if (orientation == Qt::Horizontal)
        {
            if (section == CHECK_BOX_COLUMN)
                return QStringLiteral("状态");

            if (section == File_PATH_COLUMN)
                return QStringLiteral("文件路径");
        }
    }
    default:
        return QVariant();
    }

    return QVariant();
}

// 表格可选中、可复选
Qt::ItemFlags TableModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return QAbstractItemModel::flags(index);

    Qt::ItemFlags flags = Qt::ItemIsEnabled | Qt::ItemIsSelectable;

    return flags;
}

接口说明

• updateData
  主要用于更新数据，刷新界面。

• data
  用来显示数据，根据角色（颜色、文本、对齐方式、选中状态等）判断需要显示的内容。

• setData
  用来设置数据，根据角色（颜色、文本、对齐方式、选中状态等）判断需要设置的内容。

• headerData
  用来显示水平/垂直表头的数据。

• flags
  用来设置单元格的标志（可用、可选中、可复选等）。

QStyledItemDelegate

源码

CheckBoxDelegate::CheckBoxDelegate(QObject *parent)
    : QStyledItemDelegate(parent)
{

}

CheckBoxDelegate::~CheckBoxDelegate()
{

}

// 绘制复选框
void CheckBoxDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QStyleOptionViewItem viewOption(option);
    initStyleOption(&viewOption, index);
    if (option.state.testFlag(QStyle::State_HasFocus))
        viewOption.state = viewOption.state ^ QStyle::State_HasFocus;

    QStyledItemDelegate::paint(painter, viewOption, index);

    if (index.column() == CHECK_BOX_COLUMN)
    {
        bool data = index.model()->data(index, Qt::UserRole).toBool();

        QStyleOptionButton checkBoxStyle;
        checkBoxStyle.state = data ? QStyle::State_On : QStyle::State_Off;
        checkBoxStyle.state |= QStyle::State_Enabled;
        checkBoxStyle.iconSize = QSize(20, 20);
        checkBoxStyle.rect = option.rect;

        QCheckBox checkBox;
        checkBoxStyle.iconSize = QSize(20, 20);
        checkBoxStyle.rect = option.rect;
        QApplication::style()->drawPrimitive(QStyle::PE_IndicatorCheckBox, &checkBoxStyle, painter, &checkBox);
    }
}

// 响应鼠标事件，更新数据
bool CheckBoxDelegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{
    QRect decorationRect = option.rect;

    QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event);
    if (event->type() == QEvent::MouseButtonPress && decorationRect.contains(mouseEvent->pos()))
    {
        if (index.column() == CHECK_BOX_COLUMN)
        {
            bool data = model->data(index, Qt::UserRole).toBool();
            model->setData(index, !data, Qt::UserRole);
        }
    }

    return QStyledItemDelegate::editorEvent(event, model, option, index);
}

接口说明

• paint
  用来设置表格样式，绘制复选框-状态、大小、显示区域等。

• editorEvent
  用来设置数据，响应鼠标事件，判断当前选中状态，互相切换。

样式

复选框样式：

QCheckBox{
        spacing: 5px;
        color: white;
}
QCheckBox::indicator {
        width: 17px;
        height: 17px;
}
QCheckBox::indicator:enabled:unchecked {
        image: url(:/Images/checkBox);
}
QCheckBox::indicator:enabled:unchecked:hover {
        image: url(:/Images/checkBoxHover);
}
QCheckBox::indicator:enabled:unchecked:pressed {
        image: url(:/Images/checkBoxPressed);
}
QCheckBox::indicator:enabled:checked {
        image: url(:/Images/checkBoxChecked);
}
QCheckBox::indicator:enabled:checked:hover {
        image: url(:/Images/checkBoxCheckedHover);
}
QCheckBox::indicator:enabled:checked:pressed {
        image: url(:/Images/checkBoxCheckedPressed);
}
QCheckBox::indicator:enabled:indeterminate {
        image: url(:/Images/checkBoxIndeterminate);
}
QCheckBox::indicator:enabled:indeterminate:hover {
        image: url(:/Images/checkBoxIndeterminateHover);
}
QCheckBox::indicator:enabled:indeterminate:pressed {
        image: url(:/Images/checkBoxIndeterminatePressed);
}

使用

QTableView *pTableView = new QTableView(this);
TableModel *pModel = new TableModel(this);
CheckBoxDelegate *pDelegate = new CheckBoxDelegate(this);

// 设置单行选中、最后一列拉伸、表头不高亮、无边框等
pTableView->setSelectionBehavior(QAbstractItemView::SelectRows);
pTableView->horizontalHeader()->setStretchLastSection(true);
pTableView->horizontalHeader()->setHighlightSections(false);
pTableView->verticalHeader()->setVisible(false);
pTableView->setShowGrid(false);
pTableView->setFrameShape(QFrame::NoFrame);
pTableView->setSelectionMode(QAbstractItemView::SingleSelection);
pTableView->setModel(pModel);
pTableView->setItemDelegate(pDelegate);

// 加载数据、更新界面
QList<FileRecord> recordList;
for (int i = 0; i < 5; ++i)
{
    FileRecord record;
    record.bChecked = false;
    record.strFilePath = QString("E:/Qt/image_%1.png").arg(i + 1);
    recordList.append(record);
}
pModel->updateData(recordList);