如上图所示，绘制矩形之后，可以按住中间缩放、然后按住右侧中间进行旋转，按住右下角进行缩放，按住下方中间进行斜切矩形。
整体都是仿照visionpro里面的矩形卡尺制作的。
这里主要讲一下切变，和切变之后的缩放功能。
注：我的切变暂时只支持宽度方向切变！首先，切变主要使用qt里面的
QTransform &QTransform::shear(qreal sh, qreal sv)
Shears the coordinate system by sh horizontally and sv vertically, and returns a reference to the matrix.
QTransform::shear的参数关系为：
假设矩形正中央为坐标原点（0,0），矩形边上某一点坐标在切变之前为（x1,y1），切变之后为（x2,y2），则x2=x1+sh*y1用法如下：
QTransform trans;
trans.translate(m_RECT.center().x(),m_RECT.center().y());//QRectF m_RECT为切变前的矩形
trans.shear(m_fShearX,0);
trans.translate(-m_RECT.center().x(),-m_RECT.center().y());
m_RECTShear = trans.map(m_RECTShear);//m_RECT斜切之后成了多边形QPolygonF m_RECTShear
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拖动和缩放时候需要用下面这张图来解释：因为要考虑到旋转之后依然支持切变，拖动鼠标进行切变时，切变参数sh的计算是根据鼠标在矩形横向的偏移量来计算的：
假设点pCross3和pCross5的距离dis1，点pc到pCross3的距离为h1（因为制作横向切变，所以h1=矩形高度的一半），则sh = dis1/h1;
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然后在paint（）函数里面就可以根据sh这个参数来绘制切变后的矩形。切变之后的的缩放需要保持原有的切变参数以及旋转角度，所以拖动鼠标进行缩放时，矩形的宽高的偏移量是根据如下方式计算得到的：
假设pos到直线pc pCross1的距离为h2,点pc到pCross1的距离为w2，则缩放后的新矩形参数为：QRectF newRECT = QRectF(pc.x()-w2,pc.y()-h2,w2*2,h2*2);
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核心代码如下：
头文件：#ifndef MYGRAPHICCALIPERITEM_H
#define MYGRAPHICCALIPERITEM_H
#include <QObject>
#include <QWidget>
#include <QMouseEvent>
#include <QGraphicsScene>
#include <QGraphicsRectItem>
#include <QGraphicsSceneMouseEvent>
#include <QRect>
#include <QPainter>
#include <QPolygon>
#include <QList>
#include <QTransform>
#include <QMap>
enum CALIPER_STATE_FLAG{
CALI_DEFAULT=0,
CALI_RECT_TL,//标记当前为用户按下矩形的左上角
CALI_RECT_TR,//标记当前为用户按下矩形的右上角
CALI_RECT_BL,//左下角
CALI_RECT_BR,//右下角
CALI_RECT_SHEAR,//标记当前为用户按下矩形的下边中点的切变矩形
CALI_RECT_MOVE,//标记当前为鼠标拖动矩形移动状态
CALI_RECT_ROTATE,//标记当前为旋转状态
CALIMOV_POLYGON_POINT//移动多边形的某个点
};
enum CALIPER_SHAPE_TYPE{
CALIPER_RECT,//矩形
CALIPER_LINE,
CALIPER_CIRCLE,
CALIPER_ELLIPSE
};class mygraphicCaliperitem:public QObject,public QGraphicsItem
{
Q_OBJECT
public:
CALIPER_SHAPE_TYPE m_ShapeType;
mygraphicCaliperitem(QGraphicsItem *parent = nullptr);
~mygraphicCaliperitem();
//mygraphicCaliperitem(QRectF m_OriginRect = QRectF(0,0,100,100));
QRectF boundingRect() const;
QPainterPath shape() const;
QPainterPath getCollideShape();
QPainterPath getCollideShapeTopLeftAsOriginPoint();
void setRectSize(QRectF mrect,bool bResetRotateCenter = true);
void setShearRectSize(QRectF mrect);
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
void mousePressEvent(QGraphicsSceneMouseEvent *event);
void mouseMoveEvent(QGraphicsSceneMouseEvent *event);
void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);
int type() const;
void SetRotate(qreal RotateAngle);
void SetSideCursorByRotateAngle(qreal RotateAngle);
//计算两点距离
double CalDis(const double x1, const double y1,const double x2, const double y2);
//计算点(ptx,pty)到线段(x1y1,x2y2)的距离
double CalDis(const double ptx, const double pty,const double x1, const double y1,const double x2, const double y2);
double CalDisPoint2longLine(const double ptx, const double pty,const double x1, const double y1,const double x2, const double y2);
//计算斜切后分别经过中心点和鼠标所在点的两平行线的2个焦点
bool get2CrossPt(QPointF p0, QPointF p1, QPointF p2, QPointF pc, QPointF pos, QPointF &pCross1, QPointF &pCross2);
QPointF pCross1,pCross2,pCross3,pCross5;
QPointF getRotatePoint(QPointF ptCenter, QPointF ptIn, qreal angle);//获取旋转后的点
QList<QPointF> getRotatePoints(QPointF ptCenter,QList<QPointF> ptIns,qreal angle);//获取多个旋转后的点
QPolygonF getRotatePolygonFromRect(QPointF ptCenter,QRectF rectIn,qreal angle);//将矩形旋转之后返回多边形
QPolygonF getRotatePolygonFromPolygon(QPointF ptCenter,QPolygonF polyIn,qreal angle);//将多边形旋转之后返回多边形
QRectF getBoundedRectToSceen();
QPolygonF getCrtPolygonToScreen();
QPointF getSmallRotateRectCenter(QPointF ptA,QPointF ptB);//获取旋转时候矩形正上方的旋转标记矩形
QRectF getSmallRotateRect(QPointF ptA,QPointF ptB);
qreal m_RotateAngle;
QPointF m_RotateCenter;
bool m_bKeepShadowLength;//保持投影长度不变
private:
//CALIPER_RECT矩形卡尺使用
QRectF m_RECT;
QRectF m_newShearRECT;
QPolygonF m_RECTShear;//矩形斜切后
QPolygonF m_RECT_Pol;//矩形旋转后
QPolygonF m_RECT_TL_Pol;//左上角顶点旋转后
QRectF m_RECT_TL;//左上角顶点
QPolygonF m_RECT_TR_Pol;//右上角顶点旋转后
QRectF m_RECT_TR;//右上角顶点
QPolygonF m_RECT_BL_Pol;//左下角顶点旋转后
QRectF m_RECT_BL;//左下角顶点
QPolygonF m_RECT_BR_Pol;//右下角顶点旋转后
QRectF m_RECT_BR;//右下角顶点
QPolygonF m_RECT_Inside_Pol;//内部区域旋转后
QPolygonF m_RECT_InsideShear;//内部区域斜切后
QRectF m_RECT_Inside;//内部区域
QPolygonF m_RECT_Scan_Dir_Pol;//扫描方向标记旋转后
QRectF m_RECT_Scan_Dir;//扫描方向标记
QPolygonF m_RECT_Shadow_Dir_Pol;//投影方向标记旋转后
QRectF m_RECT_Shadow_Dir;//投影方向标记
qreal m_fShadowLength;//投影长度
QPolygonF m_RECT_Rotate_Pol;//旋转的标记的矩形旋转后形成的多边形
QRectF m_RECT_Rotate;//旋转的标记的矩形
QPolygonF m_RECT_Shear_Pol;//切变矩形标记旋转后
QRectF m_RECT_Shear;//切变矩形标记
qreal m_fShearX;//切变矩形x方向参数 //
QPointF m_startPos;
CALIPER_STATE_FLAG m_StateFlag;
QMenu *pMenu;//弹出菜单
QPolygonF m_oldPolygon;
QMap<qreal,int> m_MapDis2Line;//记录鼠标右击时的坐标离m_oldPolygon中每一条线段的距离
qreal m_MinDis;//记录鼠标右击时，离m_oldPolygon最近一条线段的距离；
int m_nPolygonMovePointIndex;//移动多边形顶点的索引
int m_nPolyRemoveIndex; bool m_bResize;
protected:
private slots:
void onMenuEvent();//弹出菜单点击后响应函数
};#endif // MYGRAPHICCALIPERITEM_H
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源文件：#include "myGraphicCaliperItem.h"
#include <QtMath>
#include <QDebug>
#include <QMenu>#pragma execution_character_set("utf-8")//让能够正常显示中文字符串
mygraphicCaliperitem::mygraphicCaliperitem(QGraphicsItem *parent):
m_ShapeType(CALIPER_RECT),
m_bResize(false),
m_RECT(-100,-200,200,400),
m_RotateAngle(0),
m_bKeepShadowLength(false),
m_fShearX(0),
m_StateFlag(CALI_DEFAULT)
{
//setParent(parent);
m_newShearRECT.setWidth(0);
setRectSize(m_RECT);
//setToolTip("Click and drag me!"); //提示
setCursor(Qt::ArrowCursor); //改变光标形状,手的形状
setFlag(QGraphicsItem::ItemIsMovable);
//SetRotate(0);
//setFlag(QGraphicsItem::ItemIsSelectable);//
setFlags(QGraphicsItem::ItemIsSelectable|QGraphicsItem::ItemIsMovable);
// //创建菜单对象
// pMenu = new QMenu();//((QWidget*)this);
// QAction *pActionAddPt = new QAction("添加顶点", pMenu);
// QAction *pActionDelPt = new QAction("删除顶点", pMenu);
// //1:添加多边形顶点 2:删除多边形顶点
// pActionAddPt->setData(1);
// pActionDelPt->setData(2);// //把QAction对象添加到菜单上
// pMenu->addAction(pActionAddPt);
// pMenu->addAction(pActionDelPt);// //连接鼠标右键点击信号
// connect(pActionAddPt, SIGNAL(triggered()), this, SLOT(onMenuEvent()));
// connect(pActionDelPt, SIGNAL(triggered()), this, SLOT(onMenuEvent()));
}
void mygraphicCaliperitem::onMenuEvent()
{
// QAction *pEven = qobject_cast<QAction *>(this->sender()); //this->sender()就是发信号者 QAction
// //获取发送信息类型 //1:添加多边形顶点 2:删除多边形顶点
// int iType = pEven->data().toInt();
// switch (iType)
// {
// case 1://添加多边形顶点
// m_oldPolygon.insert(m_MapDis2Line.value(m_MinDis)+1,m_startPos);
// break;
// case 2://删除多边形顶点
// if(m_oldPolygon.count()>3)
// {
// m_oldPolygon.remove(m_nPolyRemoveIndex);
// }
// break;
// default:
// break;
// }
// scene()->update();
}
QRectF mygraphicCaliperitem::boundingRect() const//用来控制本item绘制区域
{
QPainterPath path;
if(m_ShapeType == CALIPER_RECT)
{
path.setFillRule(Qt::WindingFill);
path.addPolygon(m_RECT_Pol);
path.addPolygon(m_RECT_Rotate_Pol);
path.addPolygon(m_RECT_TL_Pol);
path.addPolygon(m_RECT_TR_Pol);
path.addPolygon(m_RECT_BL_Pol);
path.addPolygon(m_RECT_BR_Pol);
path.addPolygon(m_RECT_Shadow_Dir_Pol);
path.addPolygon(m_RECT_Shear_Pol);
}
return path.boundingRect();
}QPainterPath mygraphicCaliperitem::shape() const//用来控制检测碰撞collide和鼠标点击hit响应区域
{
QPainterPath path;
if(m_ShapeType == CALIPER_RECT)
{
path.setFillRule(Qt::WindingFill);
path.addPolygon(m_RECT_Pol);
path.addPolygon(m_RECT_Rotate_Pol);
path.addPolygon(m_RECT_TL_Pol);
path.addPolygon(m_RECT_TR_Pol);
path.addPolygon(m_RECT_BL_Pol);
path.addPolygon(m_RECT_BR_Pol);
path.addPolygon(m_RECT_Shadow_Dir_Pol);
path.addPolygon(m_RECT_Shear_Pol);
}
return path;
}QPainterPath mygraphicCaliperitem::getCollideShape()
{
QPainterPath path;
if(m_ShapeType == CALIPER_RECT)
{
path.addPolygon(m_RECT_Pol);
}
return path;
}QPainterPath mygraphicCaliperitem::getCollideShapeTopLeftAsOriginPoint()//返回左上角移动到item的（0,0）位置的collide区域
{
QPainterPath path;
if(m_ShapeType == CALIPER_RECT)
{
QTransform trans;
path.addPolygon(m_RECT_Pol);
trans.translate(-path.boundingRect().x(),-path.boundingRect().y());
path = trans.map(path);
}
return path;
}mygraphicCaliperitem::~mygraphicCaliperitem()
{}
void mygraphicCaliperitem::setRectSize(QRectF mrect, bool bResetRotateCenter)
{
m_RECT = mrect;
// if(m_newShearRECT.width() == 0)
// {
m_newShearRECT = m_RECT;
// }
if(bResetRotateCenter)
{
m_RotateCenter.setX(m_RECT.x()+m_RECT.width()/2);
m_RotateCenter.setY(m_RECT.y()+m_RECT.height()/2);
}
//test 扭曲
m_RECTShear = QPolygonF(m_RECT);
QTransform trans;
trans.translate(m_RECT.center().x(),m_RECT.center().y());
trans.shear(m_fShearX,0);
trans.translate(-m_RECT.center().x(),-m_RECT.center().y());
m_RECTShear = trans.map(m_RECTShear);//斜切之后的矩形
//test
m_RECT_Pol = getRotatePolygonFromPolygon(m_RotateCenter,m_RECTShear,m_RotateAngle); //m_RECT_Inside = QRectF(m_RECTShear[0].x()+5,m_RECTShear[0].y()+5,m_RECT.width()-10,m_RECT.height()-10);
m_RECT_InsideShear.clear();
m_RECT_InsideShear.append(QPointF(m_RECTShear[0].x()+5,m_RECTShear[0].y()+5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[1].x()-5,m_RECTShear[1].y()+5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[2].x()-5,m_RECTShear[2].y()-5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[3].x()+5,m_RECTShear[3].y()-5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[0].x()+5,m_RECTShear[0].y()+5));
m_RECT_Inside_Pol = getRotatePolygonFromPolygon(m_RotateCenter,m_RECT_InsideShear,m_RotateAngle); m_RECT_TL = QRectF(m_RECTShear[0].x()-5,m_RECTShear[0].y()-5,10,10);//左上角顶点
m_RECT_TL_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_TL,m_RotateAngle); m_RECT_TR = QRectF(m_RECTShear[1].x()-5,m_RECTShear[1].y()-5,10,10);//右上角顶点
m_RECT_TR_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_TR,m_RotateAngle); m_RECT_BL = QRectF(m_RECTShear[3].x()-5,m_RECTShear[3].y()-5,10,10);//左下角顶点
m_RECT_BL_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_BL,m_RotateAngle); m_RECT_BR = QRectF(m_RECTShear[2].x()-5,m_RECTShear[2].y()-5,10,10);//右下角顶点
m_RECT_BR_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_BR,m_RotateAngle); m_RECT_Rotate = QRectF((m_RECTShear[1].x()+m_RECTShear[2].x())/2-10,(m_RECTShear[1].y()+m_RECTShear[2].y())/2-10,20,20);//矩形右侧旋转标记矩形
m_RECT_Rotate_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_Rotate,m_RotateAngle); m_RECT_Scan_Dir = QRectF((m_RECTShear[0].x()+m_RECTShear[1].x())/2-5,(m_RECTShear[0].y()+m_RECTShear[1].y())/2-5,10,10);
QPolygonF tempPol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_Scan_Dir,m_RotateAngle);
QVector<QPointF> tempv;
tempv.append(QPointF(tempPol[0]));
tempv.append(QPointF((tempPol[1].x()+tempPol[2].x())/2,(tempPol[1].y()+tempPol[2].y())/2));
tempv.append(QPointF(tempPol[3]));
m_RECT_Scan_Dir_Pol = QPolygonF(tempv);//扫描方向的三角形 m_RECT_Shadow_Dir = QRectF(m_RECT.x()-5,m_RECT.bottomLeft().y()-15,10,10);//投影方向的三角形标记
QPolygonF tempShadow = QPolygonF(m_RECT_Shadow_Dir);
tempShadow = trans.map(tempShadow);
m_RECT_Shadow_Dir_Pol = getRotatePolygonFromPolygon(m_RotateCenter,tempShadow,m_RotateAngle); m_RECT_Shear = QRectF((m_RECTShear[2].x()+m_RECTShear[3].x())/2-5,(m_RECTShear[2].y()+m_RECTShear[3].y())/2-5,10,10);
// tempPol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_Shear,m_RotateAngle);
// tempv.clear();
// tempv.append(QPointF((tempPol[0].x()+tempPol[1].x())/2,(tempPol[0].y()+tempPol[1].y())/2));
// tempv.append(tempPol[1]);
// tempv.append(QPointF((tempPol[2].x()+tempPol[3].x())/2,(tempPol[2].y()+tempPol[3].y())/2));
// tempv.append(tempPol[3]);
// m_RECT_Shear_Pol = QPolygonF(tempv);//切变矩形标记
QPolygonF tempShear = QPolygonF(m_RECT_Shear);
QTransform transShear;
transShear.translate(m_RECT_Shear.center().x(),m_RECT_Shear.center().y());//先把中心移动到m_RECT_Shear中心
transShear.shear(1,0);
transShear.translate(-m_RECT_Shear.center().x(),-m_RECT_Shear.center().y());//先把中心移动到m_RECT_Shear中心
tempShear = transShear.map(tempShear);//斜切之后的矩形
m_RECT_Shear_Pol = getRotatePolygonFromPolygon(m_RotateCenter,tempShear,m_RotateAngle);}
void mygraphicCaliperitem::setShearRectSize(QRectF mrect)
{
m_newShearRECT = mrect;
m_RotateCenter.setX(m_newShearRECT.x()+m_newShearRECT.width()/2);
m_RotateCenter.setY(m_newShearRECT.y()+m_newShearRECT.height()/2);
//test 扭曲
m_RECTShear = QPolygonF(m_newShearRECT);
QTransform trans;
trans.translate(m_newShearRECT.center().x(),m_newShearRECT.center().y());
trans.shear(m_fShearX,0);
trans.translate(-m_newShearRECT.center().x(),-m_newShearRECT.center().y());
m_RECTShear = trans.map(m_RECTShear);//斜切之后的矩形
//test
m_RECT_Pol = getRotatePolygonFromPolygon(m_RotateCenter,m_RECTShear,m_RotateAngle); //m_RECT_Inside = QRectF(m_RECTShear[0].x()+5,m_RECTShear[0].y()+5,m_RECT.width()-10,m_RECT.height()-10);
m_RECT_InsideShear.clear();
m_RECT_InsideShear.append(QPointF(m_RECTShear[0].x()+5,m_RECTShear[0].y()+5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[1].x()-5,m_RECTShear[1].y()+5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[2].x()-5,m_RECTShear[2].y()-5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[3].x()+5,m_RECTShear[3].y()-5));
m_RECT_InsideShear.append(QPointF(m_RECTShear[0].x()+5,m_RECTShear[0].y()+5));
m_RECT_Inside_Pol = getRotatePolygonFromPolygon(m_RotateCenter,m_RECT_InsideShear,m_RotateAngle); m_RECT_TL = QRectF(m_RECTShear[0].x()-5,m_RECTShear[0].y()-5,10,10);//左上角顶点
m_RECT_TL_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_TL,m_RotateAngle); m_RECT_TR = QRectF(m_RECTShear[1].x()-5,m_RECTShear[1].y()-5,10,10);//右上角顶点
m_RECT_TR_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_TR,m_RotateAngle); m_RECT_BL = QRectF(m_RECTShear[3].x()-5,m_RECTShear[3].y()-5,10,10);//左下角顶点
m_RECT_BL_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_BL,m_RotateAngle); m_RECT_BR = QRectF(m_RECTShear[2].x()-5,m_RECTShear[2].y()-5,10,10);//右下角顶点
m_RECT_BR_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_BR,m_RotateAngle); m_RECT_Rotate = QRectF((m_RECTShear[1].x()+m_RECTShear[2].x())/2-10,(m_RECTShear[1].y()+m_RECTShear[2].y())/2-10,20,20);//矩形右侧旋转标记矩形
m_RECT_Rotate_Pol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_Rotate,m_RotateAngle); m_RECT_Scan_Dir = QRectF((m_RECTShear[0].x()+m_RECTShear[1].x())/2-5,(m_RECTShear[0].y()+m_RECTShear[1].y())/2-5,10,10);
QPolygonF tempPol = getRotatePolygonFromRect(m_RotateCenter,m_RECT_Scan_Dir,m_RotateAngle);
QVector<QPointF> tempv;
tempv.append(QPointF(tempPol[0]));
tempv.append(QPointF((tempPol[1].x()+tempPol[2].x())/2,(tempPol[1].y()+tempPol[2].y())/2));
tempv.append(QPointF(tempPol[3]));
m_RECT_Scan_Dir_Pol = QPolygonF(tempv);//扫描方向的三角形 m_RECT_Shadow_Dir = QRectF(m_newShearRECT.x()-5,m_newShearRECT.bottomLeft().y()-15,10,10);//投影方向的三角形标记
QPolygonF tempShadow = QPolygonF(m_RECT_Shadow_Dir);
tempShadow = trans.map(tempShadow);
m_RECT_Shadow_Dir_Pol = getRotatePolygonFromPolygon(m_RotateCenter,tempShadow,m_RotateAngle); m_RECT_Shear = QRectF((m_RECTShear[2].x()+m_RECTShear[3].x())/2-5,(m_RECTShear[2].y()+m_RECTShear[3].y())/2-5,10,10);
QPolygonF tempShear = QPolygonF(m_RECT_Shear);
QTransform transShear;
transShear.translate(m_RECT_Shear.center().x(),m_RECT_Shear.center().y());//先把中心移动到m_RECT_Shear中心
transShear.shear(1,0);
transShear.translate(-m_RECT_Shear.center().x(),-m_RECT_Shear.center().y());//先把中心移动到m_RECT_Shear中心
tempShear = transShear.map(tempShear);//斜切之后的矩形
m_RECT_Shear_Pol = getRotatePolygonFromPolygon(m_RotateCenter,tempShear,m_RotateAngle);}
void mygraphicCaliperitem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QPen mPen;
mPen= QPen(Qt::yellow);
painter->setPen(mPen);
if(m_ShapeType == CALIPER_RECT)
{
//绘制旋转后的矩形
painter->drawPolygon(m_RECT_Pol);
//绘制旋转圆形
mPen.setWidth(2);
mPen.setColor(Qt::green);
painter->setPen(mPen);
QPointF pf = QPointF((m_RECT_Pol[1].x()+m_RECT_Pol[2].x())/2,(m_RECT_Pol[1].y()+m_RECT_Pol[2].y())/2);
QRectF rect = QRectF(pf.x()-10,pf.y()-10,20,20);
painter->drawEllipse(rect);//绘制圆形
painter->drawPoint(pf);//绘制点
//绘制4个顶点矩形
mPen.setWidth(1);
painter->setPen(mPen);
// painter->drawPolygon(m_RECT_TL_Pol);
// painter->drawPolygon(m_RECT_TR_Pol);
// painter->drawPolygon(m_RECT_BL_Pol);
painter->drawPolygon(m_RECT_BR_Pol);
//绘制投影标记
QPointF pt0 = m_RECT_Shadow_Dir_Pol[0];
QPointF pt1 = QPointF((m_RECT_Shadow_Dir_Pol[2].x()+m_RECT_Shadow_Dir_Pol[3].x())/2,(m_RECT_Shadow_Dir_Pol[2].y()+m_RECT_Shadow_Dir_Pol[3].y())/2);
QPointF pt2 = m_RECT_Shadow_Dir_Pol[1];
painter->drawLine(pt0,pt1);
painter->drawLine(pt2,pt1);
//绘制扫描方向标记
painter->drawPolygon(m_RECT_Scan_Dir_Pol);
//绘制切变矩形标记
painter->drawPolygon(m_RECT_Shear_Pol); //painter->drawPolygon(m_RECT_Inside_Pol);
// mPen.setColor(Qt::red);
// mPen.setWidth(5);
// painter->setPen(mPen);
// painter->drawPoint(pCross1);
// painter->drawPoint(pCross2);
// painter->drawPoint(pCross3);
// painter->drawPoint(m_RECT.center());
}
}double mygraphicCaliperitem::CalDis(const double x1, const double y1, const double x2, const double y2)
{
return sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
}double mygraphicCaliperitem::CalDis(const double ptx, const double pty, const double x1, const double y1, const double x2, const double y2)
{
double f = (x2-x1)*(ptx-x1) + (y2-y1)*(pty-y1);
if (f<=0)
return CalDis(ptx, pty, x1, y1);
double d = (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1);
if (f>d)
return CalDis(ptx, pty, x2, y2);
f = f/d;
double projX = (x1 + (x2 - x1)*f);
double projY = (y1 + (y2 - y1)*f);
return CalDis(ptx, pty, projX, projY);
}double mygraphicCaliperitem::CalDisPoint2longLine(const double ptx, const double pty, const double x1, const double y1, const double x2, const double y2)
{
// double f = (x2-x1)*(ptx-x1) + (y2-y1)*(pty-y1);
if (f<=0)
return CalDis(ptx, pty, x1, y1);
// double d = (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1);
if (f>d)
return CalDis(ptx, pty, x2, y2);
// f = f/d;
// double projX = (x1 + (x2 - x1)*f);
// double projY = (y1 + (y2 - y1)*f);
// return CalDis(ptx, pty, projX, projY); //求点(ptx,pty)到直线(x1,y1)(x2,y2)的距离
//直线(x1,y1)(x2,y2)的方程为y=kx+b;
//过点(ptx,pty)的直线(x1,y1)(x2,y2)的中垂线方程为y=k2x+b2;两线交点为pCross(x0,y0)
qreal k,b,k2,b2,x0,y0;
if(x1==x2)
{
//直线方程为：x=x1
if(y1==y2)
{
//垂线方程为：x=ptx
//该情况异常，返回-1
return -1;
}
else
{
k2 = (x2-x1)/(y1-y2);
b2 = pty-k2*ptx;
x0=x1;
y0 = k2*x0+b2;
}
}
else
{
k = (y1-y2)/(x1-x2);
b = y1-k*x1;
if(y1==y2)
{
//垂线方程为：x=ptx
x0=ptx;
y0=k*x0+b;
}
else
{
k2 = (x2-x1)/(y1-y2);
b2 = pty-k2*ptx;
if(k==k2)
return -1;
else
{
x0=(b-b2)/(k2-k);
y0=k*x0+b;
}
}
}
return CalDis(x0,y0,ptx,pty);
}bool mygraphicCaliperitem::get2CrossPt(QPointF p0, QPointF p1, QPointF p2, QPointF pc, QPointF pos, QPointF &pCross1, QPointF &pCross2)
{
qreal k1,k2,b1,b2;
//假设经过pc的平行于p0p1的直线方程为：y=k1*x+b1;
if(p1.x()!=p0.x())
{
k1 = (p1.y()-p0.y())/(p1.x()-p0.x());
b1 = pc.y()-k1*pc.x();
}
//假设经过pos的平行于p1p2的直线方程为：y=k2*x+b2;
if(p1.x()!=p2.x())
{
k2 = (p2.y()-p1.y())/(p2.x()-p1.x());
b2 = pos.y()-k2*pos.x();
}
//假设两线交点为(x,y)
qreal x,y;
if(p1.x()==p0.x())
{
//则k1不存在,直线1为x=pc.x()
if(p1.x()==p2.x())
{
//k2不存在，直线2为x=pos.x()
//则两线焦点不存在，直接return
return false;
}
else
{
x=pc.x();
y = k2*x+b2;
}
}
else
{
if(p1.x()==p2.x())
{
//k2不存在，直线2为x=pos.x()
x = pos.x();
y = k1*x+b1;
}
else
{
if(k1==k2)
return false;
x=(b1-b2)/(k2-k1);
y = k1*x+b1;
}
}
pCross1=QPointF(x,y);//经过pc的平行于p0p1的直线 与 经过Pos的平行于p1p2的直线 的焦点 //假设经过pos的平行于p0p1的直线方程为：y=k3*x+b3;
//假设两线交点为(x2,y2)
qreal k3,k4,b3,b4,x2,y2;
if(p1.x()!=p0.x())
{
k3 = (p1.y()-p0.y())/(p1.x()-p0.x());
b3 = pos.y()-k3*pos.x();
}
//假设经过pc的平行于p1p2的直线方程为：y=k4*x+b4;
if(p1.x()!=p2.x())
{
k4 = (p2.y()-p1.y())/(p2.x()-p1.x());
b4 = pc.y()-k4*pc.x();
}
if(p1.x()==p0.x())
{
//则k3不存在,直线1为x=pos.x()
if(p1.x()==p2.x())
{
//k4不存在，直线2为x=pc.x()
//则两线焦点不存在，直接return
return false;
}
else
{
x2=pos.x();
y2 = k4*x2+b4;
}
}
else
{
if(p1.x()==p2.x())
{
//k4不存在，直线2为x=pc.x()
x2=pc.x();
y2 = k3*x2+b3;
}
else
{
if(k3==k4)
return false;
x2=(b3-b4)/(k4-k3);
y2 = k3*x2+b3;
}
}
pCross2=QPointF(x2,y2);//经过pc的平行于p0p1的直线 与 经过Pos的平行于p1p2的直线 的焦点
return true;
}void mygraphicCaliperitem::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
if(event->button()== Qt::LeftButton)
{
//setSelected(true);
m_startPos = event->pos();//鼠标左击时，获取当前鼠标在图片中的坐标，
if(m_ShapeType == CALIPER_RECT)//矩形卡尺
{
if(m_RECT_Rotate_Pol.containsPoint(m_startPos,Qt::WindingFill))//旋转矩形
{
m_StateFlag = CALIPER_STATE_FLAG::CALI_RECT_ROTATE;
setCursor(Qt::PointingHandCursor);
}
// else if(m_RECT_TL_Pol.containsPoint(m_startPos,Qt::WindingFill))
// {
// m_StateFlag = CALI_RECT_TL;//标记当前为用户按下矩形的左上角顶点矩形区域
// setCursor(Qt::SizeAllCursor);
// //SetSideCursorByRotateAngle(m_RotateAngle);
// }
// else if(m_RECT_TR_Pol.containsPoint(m_startPos,Qt::WindingFill))
// {
// m_StateFlag = CALI_RECT_TR;//标记当前为用户按下矩形的右上角顶点矩形区域
// setCursor(Qt::SizeAllCursor);
// //SetSideCursorByRotateAngle(m_RotateAngle);
// }
else if(m_RECT_BR_Pol.containsPoint(m_startPos,Qt::WindingFill))
{
m_StateFlag = CALI_RECT_BR;//标记当前为用户按下矩形的右下角顶点矩形区域
setCursor(Qt::SizeAllCursor);
//SetSideCursorByRotateAngle(m_RotateAngle);
}
// else if(m_RECT_BL_Pol.containsPoint(m_startPos,Qt::WindingFill))
// {
// m_StateFlag = CALI_RECT_BL;//标记当前为用户按下矩形的左下角顶点矩形区域
// setCursor(Qt::SizeAllCursor);
// //SetSideCursorByRotateAngle(m_RotateAngle);
// }
else if(m_RECT_Shear_Pol.containsPoint(m_startPos,Qt::WindingFill))//在矩形内框区域时按下鼠标，则可拖动图片
{
m_StateFlag = CALIPER_STATE_FLAG::CALI_RECT_SHEAR;//标记当前为鼠标拖动图片移动状态
setCursor(Qt::PointingHandCursor); //改变光标形状,手指的形状
}
else if(m_RECT_Inside_Pol.containsPoint(m_startPos,Qt::WindingFill))//在矩形内框区域时按下鼠标，则可拖动图片
{
m_StateFlag = CALIPER_STATE_FLAG::CALI_RECT_MOVE;//标记当前为鼠标拖动图片移动状态
setCursor(Qt::ClosedHandCursor); //改变光标形状,手的形状
}
else
{
m_StateFlag = CALI_DEFAULT;
}
}
}
else if(event->button()== Qt::RightButton)
{
m_startPos = event->pos();
//pMenu->exec(event->screenPos());//弹出菜单
}
else
{
QGraphicsItem::mousePressEvent(event);
}
}void mygraphicCaliperitem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
if(m_ShapeType == CALIPER_RECT)//矩形
{
if(m_StateFlag == CALI_RECT_ROTATE)
{
int nRotateAngle = atan2((event->pos().x()-m_RotateCenter.x()),(event->pos().y()-m_RotateCenter.y()))*180/M_PI;
SetRotate(90-nRotateAngle);
//qDebug()<<nRotateAngle;
}
else if(m_StateFlag == CALI_RECT_MOVE)
{
QPointF point = (event->pos() - m_startPos);
moveBy(point.x(), point.y());
scene()->update();
}
else if(m_StateFlag == CALI_RECT_SHEAR)//控制矩形斜切
{
QPointF pc,p0,p1,p2,p3;//,pCross1,pCross2;
pc = m_RotateCenter;
p0 = m_RECT_Pol[0];
p1 = m_RECT_Pol[1];
p2 = m_RECT_Pol[2];
p3 = m_RECT_Pol[3];
if(!get2CrossPt(p0,p1,p2,pc,event->pos(),pCross1,pCross2))
return;
//过pc做p2p3的垂线line3,line3方程为y=k3x+b3,line3与p2,p3交点为pCross3
qreal k3,b3,k4,b4;
qreal x3,y3;//pCross3(x3,y3),//y3=k3x3+b3,y3=k4x3+b4,求x3,y3
if(p3.y()==p2.y())
{
//k3不存在，lin3为x=pc.x()
//直线p2p3为y=k4x+b4
if(p3.x()==p2.x())
{
//k4不存在，直线p2p3为x=p2.x()
return;
}
else
{
k4=(p3.y()-p2.y())/(p3.x()-p2.x());
b4 = p2.y()-k4*p2.x();
//TODO:求(x3,y3)
x3 = pc.x();
y3 = k4*x3+b4;
}
}
else
{
k3 = (p2.x()-p3.x())/(p3.y()-p2.y());
b3=pc.y()-k3*pc.x();
//直线p2p3为y=k4x+b4
if(p3.x()==p2.x())
{
//k4不存在，直线p2p3为x=p2.x()
//TODO:求(x3,y3)
x3 = p2.x();
y3 = k3*x3+b3;
}
else
{
k4=(p3.y()-p2.y())/(p3.x()-p2.x());
b4 = p2.y()-k4*p2.x();
//TODO:求(x3,y3)
if(k3!=k4)
{
x3 = (b4-b3)/(k3-k4);
y3 = k3*x3+b3;
}
}
}
pCross3= QPointF(x3,y3); //过pos做p2p3的垂线line5,line5方程为y=k5x+b5,line5与p2,p3交点为pCross5
qreal k5,b5;
qreal x5,y5;//pCross5(x5,y5),//y5=k5x5+b5,y5=k4x5+b4,求x5,y5
if(p3.y()==p2.y())
{
//k3不存在，lin5为x=event->pos().x()
//直线p2p3为y=k4x+b4
if(p3.x()==p2.x())
{
//k4不存在，直线p2p3为x=p2.x()
return;
}
else
{
k4=(p3.y()-p2.y())/(p3.x()-p2.x());
b4 = p2.y()-k4*p2.x();
//TODO:求(x5,y5)
x5 = event->pos().x();
y5 = k4*x5+b4;
}
}
else
{
k5 = (p2.x()-p3.x())/(p3.y()-p2.y());
b5=event->pos().y()-k5*event->pos().x();
//直线p2p3为y=k4x+b4
if(p3.x()==p2.x())
{
//k4不存在，直线p2p3为x=p2.x()
//TODO:求(x5,y5)
x5 = p2.x();
y5 = k5*x5+b5;
}
else
{
k4=(p3.y()-p2.y())/(p3.x()-p2.x());
b4 = p2.y()-k4*p2.x();
//TODO:求(x5,y5)
if(k5!=k4)
{
x5 = (b4-b5)/(k5-k4);
y5 = k5*x5+b5;
}
}
}
pCross5= QPointF(x5,y5); //求pos到垂线line3的距离为disShear
double disShear = CalDisPoint2longLine(event->pos().x(),event->pos().y(),pc.x(),pc.y(),pCross3.x(),pCross3.y());
// double disp3pos = CalDis(p3.x(),p3.y(),event->pos().x(),event->pos().y());
// double disp2pos = CalDis(p2.x(),p2.y(),event->pos().x(),event->pos().y());
// double disp3pCross3 = CalDis(p3.x(),p3.y(),pCross3.x(),pCross3.y());
// double disp2pCross3 = CalDis(p2.x(),p2.y(),pCross3.x(),pCross3.y());
// double disVertical2RightLine = CalDisPoint2longLine(event->pos().x(),event->pos().y(),p1.x(),p1.y(),p2.x(),p2.y());
// double disVertical2LeftLine = CalDisPoint2longLine(event->pos().x(),event->pos().y(),p0.x(),p0.y(),p3.x(),p3.y());
double newHalfHeight;
if(m_bKeepShadowLength)
{
if(disShear>m_RECT.height()/2-1)
disShear = m_RECT.height()/2-1;
newHalfHeight = sqrt(qPow(m_RECT.height()/2,2)-disShear*disShear);
m_fShearX = disShear/newHalfHeight;
}
else
{
m_fShearX = disShear/(m_RECT.height()/2);
}
//确定往左斜切还是往右斜切
if(((-90<m_RotateAngle)&&(m_RotateAngle<90))||(m_RotateAngle>270 &&m_RotateAngle<360)||m_RotateAngle==360)
{
if(pCross5.x()<pCross3.x())
m_fShearX = -m_fShearX;
}
else if(m_RotateAngle == 90)
{
if(pCross5.y()<pCross3.y())
m_fShearX = -m_fShearX;
}
else if(m_RotateAngle>90&&m_RotateAngle<270)
{
if(pCross5.x()>pCross3.x())
m_fShearX = -m_fShearX;
}
else if(m_RotateAngle==270 ||m_RotateAngle == -90)
{
if(pCross5.y()>pCross3.y())
m_fShearX = -m_fShearX;
}
if(m_bKeepShadowLength)
{
setShearRectSize(QRectF(pc.x()-m_RECT.width()/2,pc.y()-newHalfHeight,m_newShearRECT.width(),newHalfHeight*2));//这个函数不会重置原始矩形的大小
}
else
{
setRectSize(m_RECT);
}
scene()->update();
// //如果是要保持投影长度不变，则矩形需要重新及计算切变前矩形的高度
// if(m_bKeepShadowLength)
// {
// double newHalfHeight = sqrt(qPow(m_RECT.height()/2,2)/(m_fShearX*m_fShearX+1));
// setShearRectSize(QRectF(pc.x()-m_RECT.width()/2,pc.y()-newHalfHeight,m_RECT.width(),newHalfHeight*2));//这个函数不会重置原始矩形的大小
// }
// else
// {
// setRectSize(m_RECT);
// }
}
else if(m_StateFlag == CALI_RECT_BR)//右下角顶点
{
QPointF pc,p0,p1,p2,p3;//,pCross1,pCross2;
pc = m_RotateCenter;
p0 = m_RECT_Pol[0];
p1 = m_RECT_Pol[1];
p2 = m_RECT_Pol[2];
p3 = m_RECT_Pol[3];
if(!get2CrossPt(p0,p1,p2,pc,event->pos(),pCross1,pCross2))
return;
// //该段代码可禁止矩形被反向拉伸！！！
// double disVertical2RightLine = CalDisPoint2longLine(event->pos().x(),event->pos().y(),p1.x(),p1.y(),p2.x(),p2.y());
// double disVertical2LeftLine = CalDisPoint2longLine(event->pos().x(),event->pos().y(),p0.x(),p0.y(),p3.x(),p3.y());
// if(disVertical2RightLine>disVertical2LeftLine)
// return;
// double disVertical2BottomLine = CalDisPoint2longLine(event->pos().x(),event->pos().y(),p2.x(),p2.y(),p3.x(),p3.y());
// double disVertical2TopLine = CalDisPoint2longLine(event->pos().x(),event->pos().y(),p0.x(),p0.y(),p1.x(),p1.y());
// if(disVertical2BottomLine>disVertical2TopLine)
// return;
// //该段代码可禁止矩形被反向拉伸！！！
if(m_bKeepShadowLength && m_fShearX!=0)//保证投影长度不变
{
double disp2pc = CalDis(m_RECTShear[2].x(),m_RECTShear[2].y(),pc.x(),pc.y());
double dispospc = CalDis(event->pos().x(),event->pos().y(),pc.x(),pc.y());
double newHeight = dispospc/disp2pc*m_newShearRECT.height();
double newWidth = dispospc/disp2pc*m_newShearRECT.width();
setShearRectSize(QRectF(pc.x()-newWidth/2,pc.y()-newHeight/2,newWidth,newHeight));
double newHeightOld = dispospc/disp2pc*m_RECT.height();
double newWidthOld = dispospc/disp2pc*m_RECT.width();
m_RECT = QRectF(pc.x()-newWidthOld/2,pc.y()-newHeightOld/2,newWidthOld,newHeightOld);
}
else//投影长度可变
{
//新矩形宽度一半：
double dispcpCross1 = CalDis(pc.x(),pc.y(),pCross1.x(),pCross1.y());
if(dispcpCross1<10)
return;//矩形宽度不能小于20
//新矩形高度一半：
double disVertical = CalDisPoint2longLine(event->pos().x(),event->pos().y(),pc.x(),pc.y(),pCross1.x(),pCross1.y());
if(disVertical<10)
return;//矩形高度不能小于20
setRectSize(QRectF(pc.x()-dispcpCross1,pc.y()-disVertical,dispcpCross1*2,disVertical*2)); }
scene()->update();
}
}
}void mygraphicCaliperitem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
setCursor(Qt::ArrowCursor);
m_StateFlag = CALI_DEFAULT;
// if(m_StateFlag == CALI_RECT_MOVE)
// {
// m_StateFlag = CALI_DEFAULT;
// }
// else {
// QGraphicsItem::mouseReleaseEvent(event);
// }
QGraphicsItem::mouseReleaseEvent(event);
//setSelected(false);
}int mygraphicCaliperitem::type() const
{
return UserType+1;//表示mygraphicCaliperitem
}void mygraphicCaliperitem::SetRotate(qreal RotateAngle)
{
m_RotateAngle = RotateAngle;
if(m_bKeepShadowLength && m_newShearRECT.width() != 0)
{
setShearRectSize(m_newShearRECT);
}
else
{
setRectSize(m_RECT);
}
if(this->scene()!=nullptr)
this->scene()->update();
}void mygraphicCaliperitem::SetSideCursorByRotateAngle(qreal RotateAngle)
{
if((RotateAngle>45&&RotateAngle<135) ||(RotateAngle>225&&RotateAngle<315))
{
if(m_StateFlag==CALI_RECT_TR ||m_StateFlag==CALI_RECT_BL)
{
setCursor(Qt::SizeFDiagCursor);
}
else if(m_StateFlag==CALI_RECT_TL ||m_StateFlag==CALI_RECT_BR)
{
setCursor(Qt::SizeBDiagCursor);
}
}
else
{
if(m_StateFlag==CALI_RECT_TR ||m_StateFlag==CALI_RECT_BL)
{
setCursor(Qt::SizeBDiagCursor);
}
else if(m_StateFlag==CALI_RECT_TL ||m_StateFlag==CALI_RECT_BR)
{
setCursor(Qt::SizeFDiagCursor);
}
}
}QPointF mygraphicCaliperitem::getRotatePoint(QPointF ptCenter, QPointF ptIn, qreal angle)
{
double dx = ptCenter.x();
double dy = ptCenter.y();
double x = ptIn.x();
double y = ptIn.y();
double xx,yy;
xx = (x-dx)*cos(angle*M_PI/180)-(y-dy)*sin(angle*M_PI/180)+dx;
yy = (x-dx)*sin(angle*M_PI/180)+(y-dy)*cos(angle*M_PI/180)+dy; return QPointF(xx,yy);
}QList<QPointF> mygraphicCaliperitem::getRotatePoints(QPointF ptCenter, QList<QPointF> ptIns, qreal angle)
{
QList<QPointF> lstPt;
for(int i = 0;i<ptIns.count();i++)
{
lstPt.append(getRotatePoint(ptCenter,ptIns.at(i),angle));
}
return lstPt;
}QPolygonF mygraphicCaliperitem::getRotatePolygonFromRect(QPointF ptCenter, QRectF rectIn, qreal angle)
{
QVector<QPointF> vpt;
QPointF pf = getRotatePoint(ptCenter,rectIn.topLeft(),angle);
vpt.append(pf);
pf = getRotatePoint(ptCenter,rectIn.topRight(),angle);
vpt.append(pf);
pf = getRotatePoint(ptCenter,rectIn.bottomRight(),angle);
vpt.append(pf);
pf = getRotatePoint(ptCenter,rectIn.bottomLeft(),angle);
vpt.append(pf);
pf = getRotatePoint(ptCenter,rectIn.topLeft(),angle);
vpt.append(pf);
return QPolygonF(vpt);
}QPolygonF mygraphicCaliperitem::getRotatePolygonFromPolygon(QPointF ptCenter, QPolygonF polyIn, qreal angle)
{
QVector<QPointF> vpt;
for(int i = 0;i<polyIn.count();i++)
{
QPointF pf = getRotatePoint(ptCenter,polyIn[i],angle);
vpt.append(pf);
}
return QPolygonF(vpt);
}QRectF mygraphicCaliperitem::getBoundedRectToSceen()
{
return QRectF(m_RECT_Pol.boundingRect().x()+pos().x(),m_RECT_Pol.boundingRect().y()+pos().y(),m_RECT_Pol.boundingRect().width(),m_RECT_Pol.boundingRect().height());
}QPolygonF mygraphicCaliperitem::getCrtPolygonToScreen()
{
QVector<QPointF> vpt;
if(m_ShapeType == CALIPER_ELLIPSE)
{
for(int i = 0;i<m_RECT_Pol.length();i++)
{
vpt.append(QPointF(m_RECT_Pol[i].x()+pos().x(),m_RECT_Pol[i].y()+pos().y()));
}
}
return QPolygonF(vpt);
}
QRectF mygraphicCaliperitem::getSmallRotateRect(QPointF ptA,QPointF ptB)
{
QPointF pt = getSmallRotateRectCenter(ptA,ptB);
return QRectF(pt.x()-10,pt.y()-10,20,20);
}QPointF mygraphicCaliperitem::getSmallRotateRectCenter(QPointF ptA,QPointF ptB)
{
QPointF ptCenter = QPointF((ptA.x()+ptB.x())/2,(ptA.y()+ptB.y())/2);//A,B点的中点C
//中垂线方程式为 y=x*k + b;
qreal x,y;//旋转图标矩形的中心
if(abs(ptB.y()-ptA.y())<0.1)
{
if(ptA.x()<ptB.x())//矩形左上角在上方
{
x = ptCenter.x();
y = ptCenter.y()-20;
}
else//矩形左上角在下方
{
x = ptCenter.x();
y = ptCenter.y()+20;
}
}
else if(ptB.y()>ptA.y())//顺时针旋转0-180
{
qreal k = (ptA.x()-ptB.x())/(ptB.y()-ptA.y());//中垂线斜率
qreal b = (ptA.y()+ptB.y())/2-k*(ptA.x()+ptB.x())/2;
//求AB线中垂线上离AB中点20个像素的点C的坐标
x = 20*cos(atan(k))+ptCenter.x();
y = k*x+b;
}
else if(ptB.y()<ptA.y())//顺时针旋转180-360
{
qreal k = (ptA.x()-ptB.x())/(ptB.y()-ptA.y());//中垂线斜率
qreal b = (ptA.y()+ptB.y())/2-k*(ptA.x()+ptB.x())/2;
//求AB线中垂线上离AB中点20个像素的点C的坐标
x = -20*cos(atan(k))+ptCenter.x();
y = k*x+b;
}
return QPointF(x,y);
}本文章为转载内容，我们尊重原作者对文章享有的著作权。如有内容错误或侵权问题，欢迎原作者联系我们进行内容更正或删除文章。
