Qt获取多边形(QGraphicsPolygonItem)或Qt图形组件与直线(QLineF)的交点 - 推酷

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//已知点和多边形//A、B点可通过多边形的boundingRect().width()/2获取;

QPointF A;

QPointF B;

QGraphicsPolygonItem yellowItem;

QLineF lineAB(A,B);

//AB连线QPointF arrowPoint; //设置交点

QPolygonF yellowtPolygon = yellowItem->polygon();

QPointF p1 = yellowtPolygon.first() + yellowItem->pos();

//遍历各边连线for (int i = 1; i < yellowtPolygon.count(); ++i) { QPointF p2 = yellowtPolygon.at(i) + yellowItem->pos();

QLineF polyLine = QLineF(p1, p2);

//核心：判断是否相交 QLineF::IntersectType intersectType = polyLine.intersect(lineAB, &arrowPoint); if (intersectType == QLineF::BoundedIntersection) break;

p1 = p2;

}

//arrowPoint 即为交点

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QPointF A;

QPointF B;

QLineF lineAB(A,B);

//AB连线

Q普通组件 m_CommentItem;

qreal commentWidth  = m_CommentItem->boundingRect().width();

qreal commentHeight = m_CommentItem->boundingRect().height();

QPointF intersectPoint;

//四个边-四条线QLineF line1(0,0,commentWidth,0

);

QLineF line2(

0,0,0

,commentHeight);

QLineF line3(commentWidth,

0

,commentWidth,commentHeight);

QLineF line4(

0

,commentHeight,commentWidth,commentHeight);

QList<QLineF> lineList;

lineList.append(line1);

lineList.append(line2);

lineList.append(line3);

lineList.append(line4);

//遍历四条线foreach

(QLineF oneline,lineList)

{

QLineF::IntersectType intersectType = oneline.intersect(lineAB, &intersectPoint); if (intersectType == QLineF::BoundedIntersection) break

;

}

//intersectPoint 即为交点