Qt通过重写QGraphicItem实现绘制拖动旋转缩放椭圆

　　本例程通过重写了一个类，继承自QGraphicItem，来实现了在qgraphicsScene上绘制、拖动、旋转、缩放椭圆
　　效果如下：
　　核心代码如下：
　　mygraphicrectitem.h
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　　点击→领取「链接」 1 #ifndef MYGRAPHICRECTITEM_H  2 #define MYGRAPHICRECTITEM_H  3 #include   4 #include   5 #include   6 #include   7 #include   8 #include   9 #include  10 #include  11 #include  12 #include  13 #include  14 enum STATE_FLAG{ 15     DEFAULT_FLAG=0, 16     MOV_LEFT_LINE,//标记当前为用户按下矩形的左边界区域 17     MOV_TOP_LINE,//标记当前为用户按下矩形的上边界区域 18     MOV_RIGHT_LINE,//标记当前为用户按下矩形的右边界区域 19     MOV_BOTTOM_LINE,//标记当前为用户按下矩形的下边界区域 20     MOV_RIGHTBOTTOM_RECT,//标记当前为用户按下矩形的右下角 21     MOV_RECT,//标记当前为鼠标拖动图片移动状态 22     ROTATE//标记当前为旋转状态 23 }; 24 enum SHAPE_TYPE{ 25     RECTANGLE=0, 26     CIRCLE 27 }; 28  29 class myGraphicRectItem:public QObject,public QGraphicsItem 30 { 31     Q_OBJECT 32 public: 33     SHAPE_TYPE m_ShapeType; 34     myGraphicRectItem(QGraphicsItem *parent = nullptr); 35     //myGraphicRectItem(QRectF m_OriginRect = QRectF(0,0,100,100)); 36     QRectF  boundingRect() const; 37     QPainterPath shape() const; 38     QPainterPath getCollideShape(); 39     ~myGraphicRectItem(); 40     void setRectSize(QRectF mrect,bool bResetRotateCenter = true); 41     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget); 42     void mousePressEvent(QGraphicsSceneMouseEvent *event); 43     void mouseMoveEvent(QGraphicsSceneMouseEvent *event); 44     void mouseReleaseEvent(QGraphicsSceneMouseEvent *event); 45     void SetRotate(qreal RotateAngle); 46     QPointF getRotatePoint(QPointF ptCenter, QPointF ptIn, qreal angle);//获取旋转后的点 47     QList getRotatePoints(QPointF ptCenter,QList ptIns,qreal angle);//获取多个旋转后的点 48     QPolygonF getRotatePolygonFromRect(QPointF ptCenter,QRectF rectIn,qreal angle);//将矩形旋转之后返回多边形 49     QRectF getCrtPosRectToSceen(); 50     QPolygonF getCrtPolygonToScreen(); 51  52     QPointF getSmallRotateRectCenter(QPointF ptA,QPointF ptB);//获取旋转时候矩形正上方的旋转标记矩形 53     QRectF  getSmallRotateRect(QPointF ptA,QPointF ptB); 54     bool    m_bRotate; 55     qreal   m_RotateAngle; 56     QPointF m_RotateCenter; 57  58 private: 59     QRectF  m_oldRect; 60     QPolygonF m_oldRectPolygon; 61     QRectF  m_RotateAreaRect; 62     bool    m_bResize; 63     QPolygonF m_insicedPolygon; 64     QRectF  m_insicedRectf; 65     QPolygonF m_leftPolygon; 66     QRectF  m_leftRectf; 67     QPolygonF m_topPolygon; 68     QRectF  m_topRectf; 69     QPolygonF m_rightPolygon; 70     QRectF  m_rightRectf; 71     QPolygonF m_bottomPolygon; 72     QRectF  m_bottomRectf; 73     QRectF m_SmallRotateRect;//矩形顶部用来表示旋转的标记的矩形 74     QPolygonF m_SmallRotatePolygon;//矩形顶部用来表示旋转的标记的矩形旋转后形成的多边形 75 //    QPolygonF m_rbPolygon; 76 //    QRectF  m_rbRectf; 77     QPointF m_startPos; 78     STATE_FLAG m_StateFlag; 79     QPointF *pPointFofSmallRotateRect; 80 protected: 81  82 }; 83  84 #endif // MYGRAPHICRECTITEM_H
　　mygraphicrectitem.cpp   1 #include ＂mygraphicrectitem.h＂   2 #include    3 #include    4    5 myGraphicRectItem::myGraphicRectItem(QGraphicsItem *parent):   6     m_ShapeType(RECTANGLE),   7     m_bResize(false),   8     m_oldRect(0,0,100,100),   9     m_bRotate(false),  10     m_RotateAngle(0),  11     m_StateFlag(DEFAULT_FLAG)  12 {  13     //setParent(parent);  14     setRectSize(m_oldRect);  15     setToolTip(＂Click and drag me!＂);  //提示  16     setCursor(Qt::ArrowCursor);   //改变光标形状,手的形状  17     setFlag(QGraphicsItem::ItemIsMovable);  18     pPointFofSmallRotateRect = new QPointF[4];  19     SetRotate(0);  20     //setFlag(QGraphicsItem::ItemIsSelectable);//  21     setFlags(QGraphicsItem::ItemIsSelectable|QGraphicsItem::ItemIsMovable);  22 }  23   24 QRectF myGraphicRectItem::boundingRect() const//用来控制本item绘制区域  25 {  26     QPainterPath path;  27     path.addPolygon(m_oldRectPolygon);  28     path.addPolygon(m_SmallRotatePolygon);  29     return path.boundingRect();  30 }  31   32 QPainterPath myGraphicRectItem::shape() const//用来控制检测碰撞collide和鼠标点击hit响应区域  33 {  34     QPainterPath path;  35     path.addPolygon(m_oldRectPolygon);  36     path.addPolygon(m_SmallRotatePolygon);  37     return path;  38 }  39   40 QPainterPath myGraphicRectItem::getCollideShape()  41 {  42     QPainterPath path;  43     if(m_ShapeType==RECTANGLE)  44     {  45         path.addPolygon(m_oldRectPolygon);  46     }  47     else if(m_ShapeType == CIRCLE)  48     {  49         QPainterPath pathTemp;  50         pathTemp.addEllipse(m_oldRect);  51         QTransform trans;  52         trans.translate(m_RotateCenter.x(),m_RotateCenter.y());  53         trans.rotate(m_RotateAngle);//QTransform是绕（0,0）点旋转的，所以转之前要先平移到圆心，然后旋转，然后再平移回来  54         trans.translate(-m_RotateCenter.x(),-m_RotateCenter.y());  55         path = trans.map(pathTemp);  56     }  57     return path;  58 }  59   60 myGraphicRectItem::~myGraphicRectItem()  61 {  62     delete []pPointFofSmallRotateRect;  63     pPointFofSmallRotateRect = nullptr;  64 }  65   66 void myGraphicRectItem::setRectSize(QRectF mrect, bool bResetRotateCenter)  67 {  68     m_oldRect = mrect;  69     if(bResetRotateCenter)  70     {  71         m_RotateCenter.setX(m_oldRect.x()+m_oldRect.width()/2);  72         m_RotateCenter.setY(m_oldRect.y()+m_oldRect.height()/2);  73     }  74     m_oldRectPolygon = getRotatePolygonFromRect(m_RotateCenter,m_oldRect,m_RotateAngle);  75   76     m_insicedRectf = QRectF(m_oldRect.x()+8,m_oldRect.y()+8,m_oldRect.width()-16,m_oldRect.height()-16);  77     m_insicedPolygon =getRotatePolygonFromRect(m_RotateCenter,m_insicedRectf,m_RotateAngle);  78   79     m_leftRectf = QRectF(m_oldRect.x(),m_oldRect.y(),8,m_oldRect.height()-8);  80     m_leftPolygon = getRotatePolygonFromRect(m_RotateCenter,m_leftRectf,m_RotateAngle);  81   82     m_topRectf = QRectF(m_oldRect.x()+8,m_oldRect.y(),m_oldRect.width()-8,8);  83     m_topPolygon = getRotatePolygonFromRect(m_RotateCenter,m_topRectf,m_RotateAngle);  84   85     m_rightRectf = QRectF(m_oldRect.right()-8,m_oldRect.y()+8,8,m_oldRect.height()-16);  86     m_rightPolygon = getRotatePolygonFromRect(m_RotateCenter,m_rightRectf,m_RotateAngle);  87   88     m_bottomRectf = QRectF(m_oldRect.x(),m_oldRect.bottom()-8,m_oldRect.width()-8,8);  89     m_bottomPolygon = getRotatePolygonFromRect(m_RotateCenter,m_bottomRectf,m_RotateAngle);  90   91     m_SmallRotateRect = getSmallRotateRect(mrect.topLeft(),mrect.topRight());//矩形正上方的旋转标记矩形  92     m_SmallRotatePolygon = getRotatePolygonFromRect(m_RotateCenter,m_SmallRotateRect,m_RotateAngle);  93   94 }  95   96 void myGraphicRectItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)  97 {  98     QPen mPen;  99 //    if(this->isSelected()) 100 //    { 101 //        mPen= QPen(Qt::lightGray); 102 //    } 103 //    else 104 //    { 105         mPen= QPen(Qt::yellow); 106 //    } 107     painter->setPen(mPen); 108     if(m_ShapeType == RECTANGLE) 109     { 110         //绘制旋转后的矩形 111         painter->drawPolygon(m_oldRectPolygon); 112         //绘制旋转圆形 113         mPen.setWidth(2); 114         mPen.setColor(Qt::green); 115         painter->setPen(mPen); 116         QPointF pf = getSmallRotateRectCenter(m_oldRectPolygon[0],m_oldRectPolygon[1]); 117         QRectF rect = QRectF(pf.x()-10,pf.y()-10,20,20); 118         painter->drawEllipse(rect);//绘制圆形 119         painter->drawPoint(pf);//绘制点 120         //有重叠的情况 121         if(!this->scene()->collidingItems(this).isEmpty()) 122         { 123            QPainterPath path,pathOthers; 124            QList lstcolliItems = this->scene()->collidingItems(this); 125            int nColliNum = lstcolliItems.count(); 126            for(int i = 0;iscene()->collidingItems(this)[i]; 129                if(pTempItem->zValue()==0) 130                { 131                    QPainterPath tempPath = pTempItem->getCollideShape(); 132                    tempPath.translate(pTempItem->pos());//转换到view中的坐标 133                    pathOthers += tempPath;//记录与本item重叠的item的路径 134                } 135            } 136            path.addPolygon(m_oldRectPolygon); 137            path.translate(this->pos());//转换到view中的坐标 138            path &= pathOthers;//计算重叠部分的路径path 139            path.translate(-this->pos().x(),-this->pos().y());//转换回本Item中的坐标 140            QBrush brush(Qt::cyan); 141            mPen.setColor(Qt::blue); 142            painter->setPen(mPen); 143            painter->setBrush(brush); 144            painter->drawPath(path);//绘制重叠区域 145         } 146     } 147     else if(m_ShapeType == CIRCLE) 148     { 149 //        //绘制旋转后的矩形 150 //        painter->drawRect(m_oldRect); 151 //        painter->drawPolygon(m_oldRectPolygon); 152         //绘制旋转后的圆形 153         QTransform trans0; 154         QPainterPath path0; 155         trans0.translate(m_RotateCenter.x(),m_RotateCenter.y()); 156         trans0.rotate(m_RotateAngle,Qt::ZAxis); 157         trans0.translate(-m_RotateCenter.x(),-m_RotateCenter.y()); 158         path0.addEllipse(m_oldRect); 159         path0 = trans0.map(path0);//将pathTemp旋转m_RotateAngle角度 160         painter->drawPath(path0);//drawPolygon(m_oldRectPolygon); 161         //绘制旋转圆形标记 162         mPen.setWidth(2); 163         mPen.setColor(Qt::green); 164         painter->setPen(mPen); 165         QPointF pf = getSmallRotateRectCenter(m_oldRectPolygon[0],m_oldRectPolygon[1]); 166         QRectF rect = QRectF(pf.x()-10,pf.y()-10,20,20); 167         painter->drawEllipse(rect);//绘制圆形 168         painter->drawPoint(pf);//绘制点 169         //有重叠的情况 170         if(!this->scene()->collidingItems(this).isEmpty()) 171         { 172            QPainterPath path,pathOthers; 173            QList lstcolliItems = this->scene()->collidingItems(this); 174            int nColliNum = lstcolliItems.count(); 175            for(int i = 0;iscene()->collidingItems(this)[i]; 178                if(pTempItem->zValue()==0) 179                { 180                    QPainterPath tempPath = pTempItem->getCollideShape(); 181                    tempPath.translate(pTempItem->pos());//转换到view中的坐标 182                    pathOthers += tempPath;//记录与本item重叠的item的路径 183                } 184            } 185            QTransform trans; 186            //旋转的时候，QTransform是绕坐标轴的（0,0）点旋转的，所以先要平移到坐标轴0，0点，然后的旋转，然后移回到原来的位置 187            trans.translate(m_RotateCenter.x(),m_RotateCenter.y()); 188            trans.rotate(m_RotateAngle); 189            trans.translate(-m_RotateCenter.x(),-m_RotateCenter.y()); 190            path.addEllipse(m_oldRect); 191            path = trans.map(path);//将pathTemp旋转m_RotateAngle角度 192            path.translate(this->pos());//转换到view中的坐标 193            path &= pathOthers;//计算重叠部分的路径path 194            path.translate(-this->pos().x(),-this->pos().y());//转换回本Item中的坐标 195            QBrush brush(Qt::cyan); 196            mPen.setColor(Qt::blue); 197            painter->setPen(mPen); 198            painter->setBrush(brush); 199            painter->drawPath(path);//绘制重叠区域 200         } 201     } 202 //scene()->update(); 203 } 204  205 void myGraphicRectItem::mousePressEvent(QGraphicsSceneMouseEvent *event) 206 { 207     if(event->button()== Qt::LeftButton) 208     { 209         //setSelected(true); 210         m_startPos = event->pos();//鼠标左击时，获取当前鼠标在图片中的坐标， 211         if(m_SmallRotatePolygon.containsPoint(m_startPos,Qt::WindingFill))//旋转矩形 212         { 213             setCursor(Qt::PointingHandCursor); 214             m_StateFlag = ROTATE; 215         } 216         else if(m_insicedPolygon.containsPoint(m_startPos,Qt::WindingFill))//在矩形内框区域时按下鼠标，则可拖动图片 217         { 218             setCursor(Qt::ClosedHandCursor);   //改变光标形状,手的形状 219             m_StateFlag = MOV_RECT;//标记当前为鼠标拖动图片移动状态 220         } 221         else if(m_leftPolygon.containsPoint(m_startPos,Qt::WindingFill)) 222         { 223             setCursor(Qt::SizeHorCursor); 224             m_StateFlag = MOV_LEFT_LINE;//标记当前为用户按下矩形的左边界区域 225         } 226         else if(m_rightPolygon.containsPoint(m_startPos,Qt::WindingFill)) 227         { 228             setCursor(Qt::SizeHorCursor); 229             m_StateFlag = MOV_RIGHT_LINE;//标记当前为用户按下矩形的右边界区域 230         } 231         else if(m_topPolygon.containsPoint(m_startPos,Qt::WindingFill)) 232         { 233             setCursor(Qt::SizeVerCursor); 234             m_StateFlag = MOV_TOP_LINE;//标记当前为用户按下矩形的上边界区域 235         } 236         else if(m_bottomPolygon.containsPoint(m_startPos,Qt::WindingFill)) 237         { 238             setCursor(Qt::SizeVerCursor); 239             m_StateFlag = MOV_BOTTOM_LINE;//标记当前为用户按下矩形的下边界区域 240         } 241 //        else if(m_rbPolygon.containsPoint(m_startPos,Qt::WindingFill)) 242 //        { 243 //            setCursor(Qt::SizeFDiagCursor); 244 //            m_StateFlag = MOV_RIGHTBOTTOM_RECT;//标记当前为用户按下矩形的右下角 245 //        } 246         else 247         { 248             m_StateFlag = DEFAULT_FLAG; 249         } 250     } 251     else 252     { 253         QGraphicsItem::mousePressEvent(event); 254     } 255 } 256  257 void myGraphicRectItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event) 258 { 259     if(m_StateFlag == ROTATE) 260     { 261        int nRotateAngle = atan2((event->pos().x()-m_RotateCenter.x()),(event->pos().y()-m_RotateCenter.y()))*180/M_PI; 262        SetRotate(180-nRotateAngle);        263        //qDebug()<pos() - m_startPos); 268         moveBy(point.x(), point.y()); 269         setRectSize(m_oldRect); 270         scene()->update(); 271     } 272     else if(m_StateFlag == MOV_LEFT_LINE) 273     { 274         QPointF pf = QPointF((m_oldRectPolygon.at(1).x()+m_oldRectPolygon.at(2).x())/2,((m_oldRectPolygon.at(1).y()+m_oldRectPolygon.at(2).y())/2)); 275         //计算到右侧边中点的距离 276         qreal dis = sqrt((event->pos().x()-pf.x())*(event->pos().x()-pf.x()) +(event->pos().y()-pf.y())*(event->pos().y()-pf.y())); 277         qreal dis2LT = sqrt((event->pos().x()-m_oldRectPolygon.at(0).x())*(event->pos().x()-m_oldRectPolygon.at(0).x()) +(event->pos().y()-m_oldRectPolygon.at(0).y())*(event->pos().y()-m_oldRectPolygon.at(0).y())); 278         qreal dis2RT = sqrt((event->pos().x()-m_oldRectPolygon.at(1).x())*(event->pos().x()-m_oldRectPolygon.at(1).x()) +(event->pos().y()-m_oldRectPolygon.at(1).y())*(event->pos().y()-m_oldRectPolygon.at(1).y())); 279         if(dis<16||dis2LT>dis2RT) 280         { 281             return; 282         } 283         else 284         { 285             QRectF newRect(m_oldRect); 286             newRect.setLeft(m_oldRect.right()-dis); 287             newRect.setRight(m_oldRect.right()); 288             setRectSize(newRect,false); 289             m_RotateCenter=QPointF((m_oldRectPolygon.at(0).x()+m_oldRectPolygon.at(2).x())/2,(m_oldRectPolygon.at(0).y()+m_oldRectPolygon.at(2).y())/2); 290             m_oldRect.moveCenter(m_RotateCenter); 291             setRectSize(m_oldRect); 292             scene()->update();//必须要用scene()->update()，不能用update();否则会出现重影 293         } 294     } 295     else if(m_StateFlag == MOV_TOP_LINE) 296     { 297         //底边中点 298         QPointF pf = QPointF((m_oldRectPolygon.at(2).x()+m_oldRectPolygon.at(3).x())/2,((m_oldRectPolygon.at(2).y()+m_oldRectPolygon.at(3).y())/2)); 299         //计算到底边中点的距离 300         qreal dis = sqrt((event->pos().x()-pf.x())*(event->pos().x()-pf.x()) +(event->pos().y()-pf.y())*(event->pos().y()-pf.y())); 301         qreal dis2LT = sqrt((event->pos().x()-m_oldRectPolygon.at(0).x())*(event->pos().x()-m_oldRectPolygon.at(0).x()) +(event->pos().y()-m_oldRectPolygon.at(0).y())*(event->pos().y()-m_oldRectPolygon.at(0).y())); 302         qreal dis2LB = sqrt((event->pos().x()-m_oldRectPolygon.at(3).x())*(event->pos().x()-m_oldRectPolygon.at(3).x()) +(event->pos().y()-m_oldRectPolygon.at(3).y())*(event->pos().y()-m_oldRectPolygon.at(3).y())); 303         if(dis<16||dis2LT>dis2LB) 304         { 305             return; 306         } 307         else 308         { 309             QRectF newRect(m_oldRect); 310             newRect.setTop(m_oldRect.bottom()-dis); 311             newRect.setBottom(m_oldRect.bottom()); 312             setRectSize(newRect,false); 313             m_RotateCenter=QPointF((m_oldRectPolygon.at(0).x()+m_oldRectPolygon.at(2).x())/2,(m_oldRectPolygon.at(0).y()+m_oldRectPolygon.at(2).y())/2); 314             m_oldRect.moveCenter(m_RotateCenter); 315             setRectSize(m_oldRect); 316             scene()->update();//必须要用scene()->update()，不能用update();否则会出现重影 317         } 318     } 319     else if(m_StateFlag == MOV_RIGHT_LINE) 320     { 321         QPointF pf = QPointF((m_oldRectPolygon.at(0).x()+m_oldRectPolygon.at(3).x())/2,((m_oldRectPolygon.at(0).y()+m_oldRectPolygon.at(3).y())/2)); 322         //计算到左侧边中点的距离 323         qreal dis = sqrt((event->pos().x()-pf.x())*(event->pos().x()-pf.x()) +(event->pos().y()-pf.y())*(event->pos().y()-pf.y())); 324         qreal dis2LT = sqrt((event->pos().x()-m_oldRectPolygon.at(0).x())*(event->pos().x()-m_oldRectPolygon.at(0).x()) +(event->pos().y()-m_oldRectPolygon.at(0).y())*(event->pos().y()-m_oldRectPolygon.at(0).y())); 325         qreal dis2RT = sqrt((event->pos().x()-m_oldRectPolygon.at(1).x())*(event->pos().x()-m_oldRectPolygon.at(1).x()) +(event->pos().y()-m_oldRectPolygon.at(1).y())*(event->pos().y()-m_oldRectPolygon.at(1).y())); 326         if(dis<16||dis2LTupdate();//必须要用scene()->update()，不能用update();否则会出现重影 340         } 341     } 342     else if(m_StateFlag == MOV_BOTTOM_LINE) 343     { 344         //顶边中点 345         QPointF pf = QPointF((m_oldRectPolygon.at(0).x()+m_oldRectPolygon.at(1).x())/2,((m_oldRectPolygon.at(0).y()+m_oldRectPolygon.at(1).y())/2)); 346         //计算到底边中点的距离 347         qreal dis = sqrt((event->pos().x()-pf.x())*(event->pos().x()-pf.x()) +(event->pos().y()-pf.y())*(event->pos().y()-pf.y())); 348         qreal dis2LT = sqrt((event->pos().x()-m_oldRectPolygon.at(0).x())*(event->pos().x()-m_oldRectPolygon.at(0).x()) +(event->pos().y()-m_oldRectPolygon.at(0).y())*(event->pos().y()-m_oldRectPolygon.at(0).y())); 349         qreal dis2LB = sqrt((event->pos().x()-m_oldRectPolygon.at(3).x())*(event->pos().x()-m_oldRectPolygon.at(3).x()) +(event->pos().y()-m_oldRectPolygon.at(3).y())*(event->pos().y()-m_oldRectPolygon.at(3).y())); 350         if(dis<16||dis2LTupdate();//必须要用scene()->update()，不能用update();否则会出现重影 364         } 365     } 366 } 367  368 void myGraphicRectItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) 369 { 370     setCursor(Qt::ArrowCursor); 371     if(m_StateFlag == MOV_RECT) 372     { 373         m_StateFlag = DEFAULT_FLAG; 374     } 375     else { 376         QGraphicsItem::mouseReleaseEvent(event); 377     } 378 } 379  380 void myGraphicRectItem::SetRotate(qreal RotateAngle) 381 { 382     m_bRotate = true; 383     m_RotateAngle = RotateAngle; 384     setRectSize(m_oldRect); 385     if(this->scene()!=nullptr) 386         this->scene()->update(); 387 } 388  389 QPointF myGraphicRectItem::getRotatePoint(QPointF ptCenter, QPointF ptIn, qreal angle) 390 { 391     double dx = ptCenter.x(); 392     double dy = ptCenter.y(); 393     double x = ptIn.x(); 394     double y = ptIn.y(); 395     double xx,yy; 396     xx = (x-dx)*cos(angle*M_PI/180)-(y-dy)*sin(angle*M_PI/180)+dx; 397     yy = (x-dx)*sin(angle*M_PI/180)+(y-dy)*cos(angle*M_PI/180)+dy; 398  399     return QPointF(xx,yy); 400 } 401  402 QList myGraphicRectItem::getRotatePoints(QPointF ptCenter, QList ptIns, qreal angle) 403 { 404     QList lstPt; 405     for(int i = 0;i vpt; 415     QPointF pf = getRotatePoint(ptCenter,rectIn.topLeft(),angle); 416     vpt.append(pf); 417     pf = getRotatePoint(ptCenter,rectIn.topRight(),angle); 418     vpt.append(pf); 419     pf = getRotatePoint(ptCenter,rectIn.bottomRight(),angle); 420     vpt.append(pf); 421     pf = getRotatePoint(ptCenter,rectIn.bottomLeft(),angle); 422     vpt.append(pf); 423     pf = getRotatePoint(ptCenter,rectIn.topLeft(),angle); 424     vpt.append(pf); 425     return QPolygonF(vpt); 426 } 427  428 QRectF myGraphicRectItem::getCrtPosRectToSceen() 429 { 430     QRectF retRect = QRectF(m_oldRect.x()+pos().x(),m_oldRect.y()+pos().y(),m_oldRect.width(),m_oldRect.height()); 431     return retRect; 432 } 433  434 QPolygonF myGraphicRectItem::getCrtPolygonToScreen() 435 { 436     QVector vpt; 437     for(int i = 0;iptA.y())//顺时针旋转0-180 467     { 468         qreal k = (ptA.x()-ptB.x())/(ptB.y()-ptA.y());//中垂线斜率 469         qreal b = (ptA.y()+ptB.y())/2-k*(ptA.x()+ptB.x())/2; 470         //求AB线中垂线上离AB中点20个像素的点C的坐标 471         x = 20*cos(atan(k))+ptCenter.x(); 472         y = k*x+b; 473     } 474     else if(ptB.y()

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