QTableWidget 安装事件过滤器无法监听到鼠标按下事件

不能直接给该窗体installEventFilter,而是该窗体的viewport添加事件过滤

与此类似的还有：

• QTreeWidget
• QTreeView
• QTableView
• QListWidget
• QListView
• QGraphicsView

在添加事件过滤器的时候，需要给视窗添加，同时在eventFilter重载函数中也需要检测窗口指针。通常情况下继承于QAbstractScrollArea的对象，都需要给viewport添加事件过滤器才会生效。

有如下继承关系图

QAbstractScrollArea
    QAbstractItemView
        QColumnView
        QHeaderView
        QListView
            QListWidget
            QUndoView
        QTableView
            QTableWidget
        QTreeView
            QTreeWidget
    QGraphicsView
    QMdiArea
    QPlainTextEdit
    QScrollArea
    QTextEdit
        QTextBrowser

示例

用户鼠标左键点击的时候，可以知道当前激活的是哪一个窗口，代码示例如下：

TestDlg::TestDlg(QWidget *parent)
    : QDialog(parent)
{
    ui.setupUi(this);

    m_pHelathTable = ui.tableWidget_health;//展示生命值的table
    m_pAttackTable = ui.tableWidget_attack;//展示攻击值的table

    m_pHelathTable->setMouseTracking(true);
    m_pAttackTable->setMouseTracking(true);
    
    m_pHelathTable->installEventFilter(this);
    m_pAttackTable->installEventFilter(this);
        
}


bool TestDlg::eventFilter(QObject * obj, QEvent * e)
{
    if(obj == m_pAttackTable->viewport()){
        if(e->type() == QEvent::MouseButtonPress){
            QMouseEvent* me = static_cast<QMouseEvent*>(e);
            if(me->button() == Qt::LeftButton)
                m_curTable = m_pAttackTable;
        }
    }
    else if(obj == m_pHelathTable->viewport()){
        if(e->type() == QEvent::MouseButtonPress){
            QMouseEvent* me = static_cast<QMouseEvent*>(e);
            if(me->button() == Qt::LeftButton)
                m_curTable = m_pHelathTable;
        }
    }
    return QDialog::eventFilter(obj,e);
}

树形控件的拖拽事件，不分监听代码如下：

bool TestDlg::eventFilter(QObject * obj, QEvent * e)
{
    if(obj == m_ETTreeWidget->viewport()){
        QEvent::Type eType = e->type();
        if(eType == QEvent::MouseMove){
            printf("MouseMove.\n");
        }
        else if(eType == QEvent::DragMove){
            printf("DragMove.\n");
        }
        else if(eType == QEvent::DragEnter){
            printf("DragEnter.\n");
        }
        else if(eType == QEvent::Drop){
            printf("Drop.\n");
        }
    }
    return QDialog::eventFilter(obj,e);
}