在QWidget上安装EventFilter(qt4.4.3/kde4)

class CustomEventFilter : public QObject
{
    Q_OBJECT

public:
    CustomEventFilter(QObject *parent = 0);

protected:
    bool eventFilter(QObject *obj, QEvent *event);
};

CustomEventFilter::CustomEventFilter(QObject *parent)
    : QObject(parent)
{
}

bool CustomEventFilter::eventFilter(QObject *obj, QEvent *event)
{
    // 在这里处理事件
    return QObject::eventFilter(obj, event);
}

MyWidget::MyWidget(QWidget *parent)
    : QWidget(parent)
{
    CustomEventFilter *filter = new CustomEventFilter(this);
    installEventFilter(filter);
}