Qt实现可拉伸矩形、圆等，可旋转角度

if(isSelected())

{

if(m_dir == Right && (event->buttons() & Qt::RightButton)){

double ang = 0;

double x = m_cenPt.x()-m_movePoint.x();

double y = m_cenPt.y()-m_movePoint.y();

if(abs(x) > 0.001){

if(x < 0){

ang = atan(y/x)*180/PI; //通过弧度求角度

if(ang < 0)

ang = atan(y/x)*180/PI 360; //通过弧度求角度

}

else

ang = atan(y/x)*180/PI 180; //通过弧度求角度

}

double oldAng = rotation();

setTransformOriginPoint(m_cenPt); //设置旋转中心

setRotation(ang oldAng); //旋转角度,如果不加oldAng,则角度旋转不对

}

else if(m_selectMod == SizeMode){

resizeTo(m_dir,event->scenePos());

}

else

QGraphicsItem::mouseMoveEvent(event); //如果在拉伸时也调用，则会位置设置不对

}