diagrams-fable-qt/src/scene/EdgeItem.cpp

#include "EdgeItem.h"

#include "DiagramScene.h"
#include "core/NetworkModel.h"
#include "core/Router.h"

#include <QPainter>
#include <QPainterPathStroker>
#include <QtMath>

namespace diag {

EdgeItem::EdgeItem(DiagramScene* scene, QUuid edgeId) : m_scene(scene), m_id(edgeId)
{
    setFlag(ItemIsSelectable);
    setZValue(0);
    setAcceptHoverEvents(true);
}

NetworkModel* EdgeItem::model() const
{
    return m_scene->model();
}

void EdgeItem::setRoute(const QList<QPointF>& poly, const QList<QPointF>& hops)
{
    prepareGeometryChange();
    m_poly = poly;
    m_hops = hops;
    const RouteConfig& cfg = m_scene->routeConfig();
    m_path = Router::toPath(poly, cfg.arcOnIntersection ? hops : QList<QPointF>{},
                            cfg.arcRadius);
    update();
}

QRectF EdgeItem::boundingRect() const
{
    const double m = 14;
    return m_path.boundingRect().adjusted(-m, -m, m, m);
}

QPainterPath EdgeItem::shape() const
{
    QPainterPathStroker stroker;
    stroker.setWidth(qMax(10.0, basePen().widthF() + 6));
    return stroker.createStroke(m_path);
}

QPen EdgeItem::basePen() const
{
    const Theme& theme = m_scene->theme();
    const Edge* e = model()->edge(m_id);
    QColor color;
    const QString colorName = model()->edgeProperty(m_id, QStringLiteral("color")).toString();
    if (QColor::isValidColorName(colorName))
        color = QColor(colorName);
    else
        color = theme.relationColor(e ? model()->registry()->relation(e->relation) : nullptr);

    const double width = model()->edgeProperty(m_id, QStringLiteral("lineWidth")).toDouble();
    const QString style = model()->edgeProperty(m_id, QStringLiteral("lineStyle")).toString();
    Qt::PenStyle penStyle = Qt::SolidLine;
    if (style == QLatin1String("Dashed"))
        penStyle = Qt::DashLine;
    else if (style == QLatin1String("Dotted"))
        penStyle = Qt::DotLine;
    else if (style == QLatin1String("DashDot"))
        penStyle = Qt::DashDotLine;

    QPen pen(color, qMax(0.5, width), penStyle, Qt::FlatCap, Qt::MiterJoin);
    return pen;
}

void EdgeItem::paint(QPainter* painter, const QStyleOptionGraphicsItem*, QWidget*)
{
    if (m_poly.size() < 2)
        return;
    painter->setRenderHint(QPainter::Antialiasing);
    const Theme& theme = m_scene->theme();
    const QPen pen = basePen();

    if (isSelected()) {
        QColor halo = theme.selection;
        halo.setAlpha(90);
        painter->setPen(QPen(halo, pen.widthF() + 6, Qt::SolidLine, Qt::RoundCap));
        painter->setBrush(Qt::NoBrush);
        painter->drawPath(m_path);
    }

    painter->setPen(pen);
    painter->setBrush(Qt::NoBrush);
    painter->drawPath(m_path);

    // End decorations sit on the raw polyline ends (arcs never reach ends).
    const QString head = model()->edgeProperty(m_id, QStringLiteral("headDecoration")).toString();
    const QString tail = model()->edgeProperty(m_id, QStringLiteral("tailDecoration")).toString();
    drawDecoration(painter, head, m_poly.last(), m_poly.at(m_poly.size() - 2), pen.color(),
                   pen.widthF());
    drawDecoration(painter, tail, m_poly.first(), m_poly.at(1), pen.color(), pen.widthF());

    if (m_scene->flowAnimationEnabled())
        drawFlowOverlay(painter, m_path, pen.widthF());

    const QString title = model()->edgeProperty(m_id, QStringLiteral("title")).toString();
    if (!title.isEmpty()) {
        const QPointF mid = Router::pointAt(m_poly, 0.5);
        painter->setPen(theme.label);
        QFont f = painter->font();
        f.setPointSizeF(8.0);
        painter->setFont(f);
        painter->drawText(QRectF(mid.x() - 60, mid.y() - 18, 120, 14), Qt::AlignCenter, title);
    }
}

void EdgeItem::drawDecoration(QPainter* painter, const QString& kind, QPointF tip, QPointF back,
                              const QColor& color, double width) const
{
    if (kind.isEmpty() || kind == QLatin1String("None"))
        return;
    QLineF dir(back, tip);
    if (dir.length() < 1e-6)
        return;
    dir.setLength(1.0);
    const QPointF u = dir.p2() - dir.p1();       // unit vector toward the tip
    const QPointF n(-u.y(), u.x());              // unit normal
    const double s = qMax(8.0, width * 3.5);     // decoration size

    painter->save();
    painter->setPen(QPen(color, qMax(1.0, width * 0.8)));
    painter->setBrush(color);
    if (kind == QLatin1String("Arrow")) {
        QPolygonF poly{tip, tip - u * s + n * s * 0.45, tip - u * s - n * s * 0.45};
        painter->drawPolygon(poly);
    } else if (kind == QLatin1String("Circle")) {
        painter->drawEllipse(tip - u * s * 0.5, s * 0.5, s * 0.5);
    } else if (kind == QLatin1String("Diamond")) {
        const QPointF c = tip - u * s * 0.5;
        QPolygonF poly{tip, c + n * s * 0.4, tip - u * s, c - n * s * 0.4};
        painter->drawPolygon(poly);
    } else if (kind == QLatin1String("Bar")) {
        painter->setPen(QPen(color, qMax(1.5, width)));
        painter->drawLine(tip + n * s * 0.5, tip - n * s * 0.5);
    }
    painter->restore();
}

void EdgeItem::drawFlowOverlay(QPainter* painter, const QPainterPath& path, double width) const
{
    const Edge* e = model()->edge(m_id);
    if (!e || qAbs(e->flowRate) < 1e-9)
        return;
    const double maxFlow = qMax(1e-9, m_scene->maxAbsFlow());
    const double ratio = qBound(0.15, qAbs(e->flowRate) / maxFlow, 1.0);

    // Moving dashes: speed and thickness encode volume, offset sign encodes
    // direction (positive flow runs from tail to head).
    QPen pen(m_scene->theme().flowOverlay, qMax(1.0, width * (0.25 + 0.45 * ratio)),
             Qt::CustomDashLine, Qt::FlatCap);
    pen.setDashPattern({1.2, 3.2});
    const double dir = e->flowRate > 0 ? -1.0 : 1.0;
    pen.setDashOffset(dir * m_scene->animationPhase() * (0.4 + 1.6 * ratio));
    painter->setPen(pen);
    painter->setBrush(Qt::NoBrush);
    painter->drawPath(path);
}

}  // namespace diag