void MyTabBar::mousePressEvent(QMouseEvent *event)
{
    QTabBar::mousePressEvent(event);
    if(event->button()==Qt::LeftButton&&currentIndex()>=0)
    {
        //保存状态
        //pressPos=event->pos();
        theDragPress=true;
    }
}

void MyTabBar::mouseMoveEvent(QMouseEvent *event)
{
    QTabBar::mouseMoveEvent(event);

    //move的时候button为NoButton，但是button's里有
    if(theDragPress&&event->buttons())
    {
        //是否脱离了tabbar的范围
        if(!theDragOut&&!contentsRect().contains(event->pos())){
            theDragOut=true;
            emit beginDragOut(this->currentIndex());

            //QDrag.exec后就不会触发release了，自己手动触发
            //不过他好像还是在鼠标弹起之后才会进行动画，待解决
            QMouseEvent *e=new QMouseEvent(QEvent::MouseButtonRelease,
                                              this->mapFromGlobal(QCursor::pos()),
                                               Qt::LeftButton,
                                               Qt::LeftButton,
                                               Qt::NoModifier);
            //mouseReleaseEvent(event);
            QApplication::postEvent(this,e);
        }
    }
}

void MyTabBar::mouseReleaseEvent(QMouseEvent *event)
{
    QTabBar::mouseReleaseEvent(event);
    theDragPress=false;
    theDragOut=false;
}

void MyTabWidget::initTabBar()
{
MyTabBar *bar=new MyTabBar(this);
//setTabBar是protected成员函数，要使用就得继承
setTabBar(bar);
//点击页签上的关闭按钮时，触发信号
connect(bar,&QTabBar::tabCloseRequested,this,&MyTabWidget::removeNormalIndex);
//拖拽到外部-还未释放鼠标
connect(bar,&MyTabBar::beginDragOut,this,[this,bar](int index){
if(!indexValid(index))
return;
QWidget *drag_tab=this->widget(index);
//固定tab就不让拖出
if(!drag_tab||fixedPage.contains(drag_tab))
return;
//把当前页作为快照拖拽
//尺寸加了标题栏和边框
QPixmap pixmap(drag_tab->size()+QSize(2,31));
pixmap.fill(Qt::transparent);
QPainter painter(&pixmap);
if(painter.isActive())
{
//这里想做标题栏贴在内容之上
//但是没法获取默认标题栏的图像啊，就随便画一个矩形框
//如果设置了外部主题颜色，需要改下
QRect title_rect{0,0,pixmap.width(),30};
painter.fillRect(title_rect,Qt::white);
painter.drawText(title_rect,Qt::AlignLeft|Qt::AlignVCenter,"  "+drag_tab->windowTitle());
painter.drawRect(pixmap.rect().adjusted(0,0,-1,-1));
}
painter.end();
drag_tab->render(&pixmap,QPoint(1,30));
QMimeData *mime=new QMimeData;
QDrag *drag=new QDrag(bar);
drag->setMimeData(mime);
drag->setPixmap(pixmap);
drag->setHotSpot(QPoint(10,0));
//鼠标弹起后drag就释放了，这时候去判断是否拖拽到了外部
connect(drag,&QDrag::destroyed,this,[=]{
QPoint bar_point=bar->mapFromGlobal(QCursor::pos());
//不在范围，拖出
if(!bar->contentsRect().contains(bar_point)){
popPage(drag_tab);
}
});
drag->exec(Qt::MoveAction);
});
}
void MyTabWidget::popPage(QWidget *page)
{
takeNormalPage(page);
//这里套一个自定义标题栏的窗口给page
MyTabPopup *pop=new MyTabPopup(this);
pop->setAttribute(Qt::WA_DeleteOnClose);
pop->setContentWidget(page);
pop->setWindowTitle(page->windowTitle());
pop->resize(page->size());
//拖出来的位置有点偏移
pop->move(QCursor::pos()-QPoint(10,10));
//判断独立窗口是否拖回tab
connect(pop,&MyTabPopup::dragRelease,this,[=](const QPoint &pos){
const QPoint bar_pos=tabBar()->mapFromGlobal(pos);
//如果又拖回了tabbar范围内，就把widget取出来放回tab
if(tabBar()->contentsRect().contains(bar_pos))
{
QWidget *content=pop->getContentWidget();
this->appendNormalPage(content);
pop->disconnect();
//关闭的时候会在原来的位置闪一下？
pop->close();
//this->activateWindow();
}
});
pop->show();
page->show();
pop->activateWindow();
pop->setFocus();
}