效果圖
qwharrowitem類標頭檔案
#ifndef qwharrowitem_h
#define qwharrowitem_h
#include #include "qwhcircleitem.h"
class qwharrowitem : public qgraphicslineitem
; explicit qwharrowitem(qwhcircleitem *startitem, qwhcircleitem *enditem, qgraphicsitem *parent = nullptr);
~qwharrowitem();
int type() const override;
qrectf boundingrect() const override;
qpainterpath shape() const override;
protected:
void paint(qpainter *painter, const qstyleoptiongraphicsitem *option, qwidget *widget = nullptr) override;
public:
//位置更新
void updateposition();
//獲取起始item
qwhcircleitem *getstartitem();
//獲取結束item
qwhcircleitem *getenditem();
private:
qwhcircleitem *m_startitem; //起始item
qwhcircleitem *m_enditem; //結束item
qreal m_arrowsize; //箭頭大小
qcolor m_linecolor; //線條顏色
qcolor m_arrowcolor; //箭頭顏色
};#endif // qwharrowitem_h
void qwharrowitem::paint(qpainter *painter, const qstyleoptiongraphicsitem *option, qwidget *widget)
radians += m_pi;
//獲取圓和直線的交點，箭頭繪製在交點處，不繪製在圓心（直線末端）
qpointf startpoint = line().p1() + qpointf(startitemradius * qcos(radians + m_pi), -startitemradius * qsin(radians + m_pi));
qpointf endpoint = line().p2() + qpointf(enditemradius * qcos(radians), -enditemradius * qsin(radians));
double radiusl = radians - qdegreestoradians(30.0); //箭頭左邊線段，角度可變
double radiusr = radians + qdegreestoradians(30.0); //箭頭右邊線段，角度可變
qpointf pointl = qpointf(endpoint.x() + m_arrowsize * qcos(radiusl), endpoint.y() - m_arrowsize * qsin(radiusl));
qpointf pointr = qpointf(endpoint.x() + m_arrowsize * qcos(radiusr), endpoint.y() - m_arrowsize * qsin(radiusr));
qlinef linel = qlinef(endpoint, pointl);
qlinef liner = qlinef(endpoint, pointr);
painter->setpen(qpen(m_linecolor, 2, qt::solidline, qt::roundcap, qt::roundjoin));
painter->drawline(startpoint, endpoint);
qpainterpath path;
path.moveto(endpoint);
path.lineto(pointl);
path.lineto(pointr);
painter->fillpath(path, m_arrowcolor);
}
#ifndef qwhcircleitem_h
#define qwhcircleitem_h
#include class qwharrowitem;
class qwhcircleitem : public qgraphicsellipseitem
; explicit qwhcircleitem(qpointf pos, qreal radius, qgraphicsitem *parent = nullptr);
~qwhcircleitem();
int type() const override;
public:
//新增箭頭
void addarrow(qwharrowitem *arrow);
//移除箭頭
void removearrow(qwharrowitem *arrow);
//移出所有箭頭
void removearrows();
//獲取半徑
qreal radius();
protected:
//位置改變
qvariant itemchange(qgraphicsitem::graphicsitemchange change, const qvariant &value) override;
private:
qlistm_arrows; //箭頭集合
qreal m_radius; //半徑
};#endif // qwhcircleitem_h
void qwhcircleitem::removearrows()
}qvariant qwhcircleitem::itemchange(qgraphicsitem::graphicsitemchange change, const qvariant &value)
return value;
}
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