alignmentguide.h

Go to the documentation of this file.

/*
    SPDX-License-Identifier: GPL-2.0-or-later
    SPDX-FileCopyrightText: 2025 Umbrello UML Modeller Authors <umbrello-devel@kde.org>
*/
 
#ifndef ALIGNMENTGUIDE_H
#define ALIGNMENTGUIDE_H
 
#include <QPointF>
#include <QList>
#include <QLineF>
 
class UMLWidget;
class UMLScene;

class AlignmentGuide
{
public:
    enum class GuideType {
        None,
        LeftEdge,
        RightEdge,
        HorizontalCenter,
        TopEdge,
        BottomEdge,
        VerticalCenter
    };

    struct GuideLine {
        GuideType type;
        qreal position;  // X coordinate for vertical lines, Y for horizontal
 
        GuideLine() : type(GuideType::None), position(0.0) {}
        GuideLine(GuideType t, qreal pos) : type(t), position(pos) {}
 
        bool isHorizontal() const {
            return type == GuideType::TopEdge ||
                   type == GuideType::BottomEdge ||
                   type == GuideType::VerticalCenter;
        }
 
        bool isVertical() const {
            return type == GuideType::LeftEdge ||
                   type == GuideType::RightEdge ||
                   type == GuideType::HorizontalCenter;
        }
    };
 
    explicit AlignmentGuide(UMLScene *scene);
    ~AlignmentGuide();

    QPointF snapPosition(UMLWidget *widget, const QPointF &proposedPos);

    void snapResize(UMLWidget *widget, qreal proposedWidth, qreal proposedHeight,
                    qreal &newWidth, qreal &newHeight);

    QList<GuideLine> activeGuides() const;

    void clear();

    void setSnapThreshold(qreal threshold);

    qreal snapThreshold() const;

    void setEnabled(bool enabled);

    bool isEnabled() const;
 
private:
    struct AlignmentPoints {
        qreal left;
        qreal right;
        qreal hCenter;  // horizontal center
        qreal top;
        qreal bottom;
        qreal vCenter;  // vertical center
    };
 
    AlignmentPoints getAlignmentPoints(UMLWidget *widget, const QPointF &pos) const;

    void findBestSnap(qreal position, const QList<qreal> &candidates,
                      qreal &minDistance, qreal &bestSnap, qreal &offset,
                      GuideType &bestGuideType, GuideType guideType) const;
 
    UMLScene *m_scene;
    QList<GuideLine> m_activeGuides;
    qreal m_snapThreshold;
    bool m_enabled;
};
 
#endif // ALIGNMENTGUIDE_H