#include "DraggableLine.h"
void DraggableLine::mousePressEvent(QGraphicsSceneMouseEvent* event) {
    // 判断点击的是起点还是终点
    QPointF clickPos = event->pos();
    if (distance(clickPos, line().p1()) < 10) {
        draggingStart = true;
    } else if (distance(clickPos, line().p2()) < 10) {
        draggingEnd = true;
    }
}

void DraggableLine::mouseMoveEvent(QGraphicsSceneMouseEvent* event)  {
    if (draggingStart) {
        // 更新起点坐标
        QLineF newLine(event->scenePos(), line().p2());
        setLine(newLine);
    } else if (draggingEnd) {
        // 更新终点坐标
        QLineF newLine(line().p1(), event->scenePos());
        setLine(newLine);
    }
    update();
}
void DraggableLine::mouseReleaseEvent(QGraphicsSceneMouseEvent*)  {
    draggingStart = draggingEnd = false;
}

void DraggableLine::paint(QPainter* painter, const QStyleOptionGraphicsItem*, QWidget*) {
    painter->setPen(QPen(Qt::blue, 2));
    painter->drawLine(line());

    // 绘制可拖拽端点
    painter->setBrush(Qt::red);
    painter->drawEllipse(line().p1(), 5, 5);
    painter->drawEllipse(line().p2(), 5, 5);
}

double DraggableLine::distance(const QPointF& p1, const QPointF& p2) {
    return QLineF(p1, p2).length();
}