簡述

前面分享了QTableView中如何新增複選框。本節主要介紹QTableView中的表頭-QHeaderView新增複選框的功能，下面以水平表頭為例，垂直表頭類似！

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效果

QHeaderView

原始碼

TableHeaderView::TableHeaderView(Qt::Orientation orientation, QWidget *parent)
    : QHeaderView(orientation, parent),
      m_bPressed(false),
      m_bChecked(false),
      m_bTristate(false
 
),
      m_bNoChange(false),
      m_bMoving(false)
{
    // setStretchLastSection(true);
    setHighlightSections(false);
    setMouseTracking(true);

    // 響應滑鼠
    setSectionsClickable(true);
}

// 槽函式，用於更新複選框狀態
void TableHeaderView::onStateChanged(int state)
{
    if (state == Qt::PartiallyChecked) {
        m_bTristate =
 
 true;
        m_bNoChange = true;
    } else {
        m_bNoChange = false;
    }

    m_bChecked = (state != Qt::Unchecked);
    update();
}

// 繪製複選框
void TableHeaderView::paintSection(QPainter *painter, const QRect &rect, int logicalIndex) const
{
    painter->save();
    QHeaderView::paintSection
 
(painter, rect, logicalIndex);
    painter->restore();

    if (logicalIndex == CHECK_BOX_COLUMN)
    {
        QStyleOptionButton option;
        option.initFrom(this);

        if (m_bChecked)
            option.state |= QStyle::State_Sunken;

        if (m_bTristate && m_bNoChange)
            option.state |= QStyle::State_NoChange;
        else
            option.state |= m_bChecked ? QStyle::State_On : QStyle::State_Off;
        if (testAttribute(Qt::WA_Hover) && underMouse()) {
            if (m_bMoving)
                option.state |= QStyle::State_MouseOver;
            else
                option.state &= ~QStyle::State_MouseOver;
        }

        QCheckBox checkBox;
        option.iconSize = QSize(20, 20);
        option.rect = rect;
        style()->drawPrimitive(QStyle::PE_IndicatorCheckBox, &option, painter, &checkBox);
        //style()->drawItemPixmap(painter, rect, Qt::AlignCenter, QPixmap(":/images/checkBoxChecked"));
        //style()->drawControl(QStyle::CE_CheckBox, &option, painter, this);
    }
}

// 滑鼠按下表頭
void TableHeaderView::mousePressEvent(QMouseEvent *event)
{
    int nColumn = logicalIndexAt(event->pos());
    if ((event->buttons() & Qt::LeftButton) && (nColumn == CHECK_BOX_COLUMN))
    {
        m_bPressed = true;
    }
    else
    {
        QHeaderView::mousePressEvent(event);
    }
}

// 滑鼠從表頭釋放，傳送訊號，更新model資料
void TableHeaderView::mouseReleaseEvent(QMouseEvent *event)
{
    if (m_bPressed)
    {
        if (m_bTristate && m_bNoChange)
        {
            m_bChecked = true;
            m_bNoChange = false;
        }
        else
        {
            m_bChecked = !m_bChecked;
        }

        update();

        Qt::CheckState state = m_bChecked ? Qt::Checked : Qt::Unchecked;

        emit stateChanged(state);
    }
    else
    {
        QHeaderView::mouseReleaseEvent(event);
    }

    m_bPressed = false;
}

// 滑鼠滑過、離開，更新複選框狀態
bool TableHeaderView::event(QEvent *event)
{
    if (event->type() == QEvent::Enter || event->type() == QEvent::Leave)
    {
        QMouseEvent *pEvent = static_cast<QMouseEvent *>(event);
        int nColumn = logicalIndexAt(pEvent->x());
        if (nColumn == CHECK_BOX_COLUMN)
        {
            m_bMoving = (event->type() == QEvent::Enter);

            update();
            return true;
        }
    }

    return QHeaderView::event(event);
}

介面說明

• onStateChanged
  槽函式，與model關聯，當model的資料發生變化時，表頭複選中狀態也隨之變化。

• paintSection
  繪製部分，主要用於繪製複選框，主要設定QStyleOptionButton的狀態，然後通過QStyle的drawPrimitive繪製樣式。

• mousePressEvent
  滑鼠按下表頭，設定被按下的標誌為true。

• mouseReleaseEvent
  滑鼠從表頭釋放，傳送訊號，更新model資料。

• event
  滑鼠滑過、離開，更新複選框狀態。

QAbstractTableModel

原始碼

// 設定表格項資料
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);

            if (role == Qt::UserRole)
                onStateChanged();
            return true;
        }
    }
    default:
        return false;
    }
    return false;
}

// 複選狀態改變，通知表頭更新複選狀態
void TableModel::onStateChanged()
{
    Qt::CheckState state = Qt::Unchecked;
    int nCount = m_recordList.count();
    int nSelectedCount = 0;
    FileRecord record;
    for (int i = 0; i < nCount; ++i)
    {
        record = m_recordList.at(i);
        if (record.bChecked)
            ++nSelectedCount;
    }

    if (nSelectedCount >= nCount)
    {
        state = Qt::Checked;
    }
    else if (nSelectedCount > 0)
    {
        state = Qt::PartiallyChecked;
    }

    emit stateChanged(state);
}

// 接收表頭複選狀態更新變化，修改表格複選狀態
void TableModel::onStateChanged(int state)
{
    QModelIndex index;
    for (int i = 0; i < rowCount(); ++i)
    {
        index = this->index(i, CHECK_BOX_COLUMN);
        setData(index, state == Qt::Checked, Qt::CheckStateRole);
    }
}

介面說明

• setData
  設定表格項資料，關鍵程式碼：當role為Qt::UserRole時候，會呼叫onStateChanged()函式，來更新表頭！

• onStateChanged
  複選狀態改變，通知表頭更新複選狀態。

• onStateChanged(int state)
  槽函式，接收表頭複選狀態更新變化，修改表格複選狀態。

使用

這時，就需要將header與model的訊號與槽關聯起來，更新複選框狀態了！

QTableView *pTableView = new QTableView(this);
TableModel *pModel = new TableModel(this);
TableHeaderView *pHeader = new TableHeaderView(Qt::Horizontal, this);
CheckBoxDelegate *pDelegate = new CheckBoxDelegate(this);

pTableView->setHorizontalHeader(pHeader);
pTableView->setModel(pModel);
pTableView->setItemDelegate(pDelegate);

connect(pModel, SIGNAL(stateChanged(int)), pHeader, SLOT(onStateChanged(int)));
connect(pHeader, SIGNAL(stateChanged(int)), pModel, SLOT(onStateChanged(int)));