计算两条直线QLineF的重叠部分

效果

使用示例

    QLineF intersection;bool isSuccess = GetOverlapSegment(line1, line2, intersection);

源码

// 判断两个QLineF对象在斜率相同时是否存在重叠部分
bool DoLineOverlapWithSameSlope(const QLineF& line1, const QLineF& line2)
{qreal slope1 = line1.dy() / line1.dx();qreal slope2 = line2.dy() / line2.dx();// 引入误差范围qreal epsilon = 1e-6;if (std::abs(slope1 - slope2) > epsilon) {return false; // 斜率不相等，直接返回false}qreal b1 = line1.p1().y() - slope1 * line1.p1().x();qreal b2 = line2.p1().y() - slope1 * line2.p1().x();qreal x_overlap = (b2 - b1) / (slope1 - slope2);if (x_overlap < qMin(line1.p1().x(), line1.p2().x()) ||x_overlap > qMax(line1.p1().x(), line1.p2().x()) ||x_overlap < qMin(line2.p1().x(), line2.p2().x()) ||x_overlap > qMax(line2.p1().x(), line2.p2().x())) {return false;}return true;
}bool GetOverlapSegment(const QLineF& line1, const QLineF& line2, QLineF& overlap)
{bool is_overlap = DoLineOverlapWithSameSlope(line1, line2);if (!is_overlap) return false;qreal start1 = qMin(line1.p1().x(), line1.p2().x());qreal end1 = qMax(line1.p1().x(), line1.p2().x());qreal start2 = qMin(line2.p1().x(), line2.p2().x());qreal end2 = qMax(line2.p1().x(), line2.p2().x());qreal overlapStart = qMax(start1, start2);qreal overlapEnd = qMin(end1, end2);if (overlapStart <= overlapEnd) {qreal minY1 = qMin(line1.p1().y(), line1.p2().y());qreal maxY1 = qMax(line1.p1().y(), line1.p2().y());qreal minY2 = qMin(line2.p1().y(), line2.p2().y());qreal maxY2 = qMax(line2.p1().y(), line2.p2().y());qreal overlapMinY = qMax(minY1, minY2);qreal overlapMaxY = qMin(maxY1, maxY2);overlap.setP1(QPointF(overlapStart, overlapMinY));overlap.setP2(QPointF(overlapEnd, overlapMaxY));return true;}return false;
}