bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
    if (event->type() == QEvent::MouseMove) {  //鼠标移动事件
        QMouseEvent *mouseMove = static_cast<QMouseEvent*>(event);  
        QRect rect = widget->frameGeometry();  //widget区域
        if (rect.contains(mouseMove->pos())) {  //鼠标在widget区域内则显示
            //颜色处理
        }
    }
    return QWidget::eventFilter(obj, event);
}