QT用QGraphicsLineItem实现曼哈顿连线，直接可以用，方便移植项目

#include "manhattanlineitem.h" ManhattanLineItem::ManhattanLineItem(QPointF start, QPointF end, QGraphicsLineItem *parent) : QGraphicsLineItem(parent), mStart(start), mEnd(end) { // 设置画笔、画刷、包围盒等属性 setZValue(-1); prepareGeometryChange(); } QRectF ManhattanLineItem::boundingRect() const { qreal minX = qMin(mStart.x(), mEnd.x()); qreal minY = qMin(mStart.y(), mEnd.y()); qreal maxX = qMax(mStart.x(), mEnd.x()); qreal maxY = qMax(mStart.y(), mEnd.y()); return QRectF(minX, minY, maxX - minX, maxY - minY); } void ManhattanLineItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) { painter->setRenderHint(QPainter::Antialiasing, true); painter->setPen(QPen(Qt::red, 2)); //painter->setBrush(QBrush(Qt::red)); // 计算曼哈顿距离 QPointF delta = mEnd - mStart; qreal length = qAbs(delta.x()) + qAbs(delta.y()); // 构造QPainterPath对象 QPainterPath path(mStart); if (delta.x() > 0) { path.lineTo(mStart.x() + qMin(delta.x(), length / 2), mStart.y()); if (delta.y() > 0) { path.lineTo(mStart.x() + qMin(delta.x(), length / 2), mEnd.y()); path.lineTo(mEnd.x(), mEnd.y()); } else { path.lineTo(mStart.x() + qMin(delta.x(), length / 2), mEnd.y()); path.lineTo(mEnd.x(), mEnd.y()); } } else { path.lineTo(mStart.x() - qMin(-delta.x(), length / 2), mStart.y()); if (delta.y() > 0) { path.lineTo(mStart.x() - qMin(-delta.x(), length / 2), mEnd.y()); path.lineTo(mEnd.x(), mEnd.y()); } else { path.lineTo(mStart.x() - qMin(-delta.x(), length / 2), mEnd.y()); path.lineTo(mEnd.x(), mEnd.y()); } } painter->drawPath(path); } void ManhattanLineItem::updateLine(QPointF start, QPointF end) { prepareGeometryChange(); mStart = start; mEnd = end; }