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

bool getOverlapSegment(const QLineF& line1, const QLineF& line2, QLineF& overlap)
{
    qreal slope1 = (line1.p2().y() - line1.p1().y()) / (line1.p2().x() - line1.p1().x());
    qreal slope2 = (line2.p2().y() - line2.p1().y()) / (line2.p2().x() - line2.p1().x());

    // Check if the lines are parallel
    if (qAbs(slope1 - slope2) < 0.0001) {
        // Check if the lines are not overlapping
        if (qAbs(line1.p1().x() - line2.p2().x()) > 0.0001 && qAbs(line1.p1().y() - line2.p2().y()) > 0.0001 &&
            qAbs(line1.p2().x() - line2.p1().x()) > 0.0001 && qAbs(line1.p2().y() - line2.p1().y()) > 0.0001) {
            return false; // Lines are parallel but not overlapping
        }
    }

    // Calculate intersection point
    qreal x = (slope1 * line1.p1().x() - slope2 * line2.p1().x() + line2.p1().y() - line1.p1().y()) / (slope1 - slope2);
    qreal y = slope1 * (x - line1.p1().x()) + line1.p1().y();

    // Check if the intersection point is within the line segments
    if (x < qMin(line1.p1().x(), line1.p2().x()) || x > qMax(line1.p1().x(), line1.p2().x()) ||
        x < qMin(line2.p1().x(), line2.p2().x()) || x > qMax(line2.p1().x(), line2.p2().x()) ||
        y < qMin(line1.p1().y(), line1.p2().y()) || y > qMax(line1.p1().y(), line1.p2().y()) ||
        y < qMin(line2.p1().y(), line2.p2().y()) || y > qMax(line2.p1().y(), line2.p2().y())) {
        return false; // Lines intersect, but not within line segments
    }

    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;
}