qpathclipper_p.h

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#ifndef QPATHCLIPPER_P_H
#define QPATHCLIPPER_P_H
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
 
#include <QtGui/private/qtguiglobal_p.h>
#include <QtGui/qpainterpath.h>
#include <QtCore/qlist.h>
 
#include <private/qbezier_p.h>
#include <private/qdatabuffer_p.h>
#include <stdio.h>
 
QT_BEGIN_NAMESPACE
 
 
class QWingedEdge;
 
class Q_GUI_EXPORT QPathClipper
{
public:
    enum Operation {
        BoolAnd,
        BoolOr,
        BoolSub,
        Simplify
    };
public:
    QPathClipper(const QPainterPath &subject,
                 const QPainterPath &clip);
 
    QPainterPath clip(Operation op = BoolAnd);
 
    bool intersect();
    bool contains();
 
    static bool pathToRect(const QPainterPath &path, QRectF *rect = nullptr);
    static QPainterPath intersect(const QPainterPath &path, const QRectF &rect);
 
private:
    Q_DISABLE_COPY_MOVE(QPathClipper)
 
    enum ClipperMode {
        ClipMode, // do the full clip
        CheckMode // for contains/intersects (only interested in whether the result path is non-empty)
    };
 
    bool handleCrossingEdges(QWingedEdge &list, qreal y, ClipperMode mode);
    bool doClip(QWingedEdge &list, ClipperMode mode);
 
    QPainterPath subjectPath;
    QPainterPath clipPath;
    Operation op;
 
    int aMask;
    int bMask;
};
 
struct QPathVertex
{
public:
    QPathVertex(const QPointF &p = QPointF(), int e = -1);
    operator QPointF() const;
 
    int edge;
 
    qreal x;
    qreal y;
};
Q_DECLARE_TYPEINFO(QPathVertex, Q_PRIMITIVE_TYPE);
 
class QPathEdge
{
public:
    enum Traversal {
        RightTraversal,
        LeftTraversal
    };
 
    enum Direction {
        Forward,
        Backward
    };
 
    enum Type {
        Line,
        Curve
    };
 
    explicit QPathEdge(int a = -1, int b = -1);
 
    mutable int flag;
 
    int windingA;
    int windingB;
 
    int first;
    int second;
 
    double angle;
    double invAngle;
 
    int next(Traversal traversal, Direction direction) const;
 
    void setNext(Traversal traversal, Direction direction, int next);
    void setNext(Direction direction, int next);
 
    Direction directionTo(int vertex) const;
    int vertex(Direction direction) const;
 
private:
    int m_next[2][2] = { { -1, -1 }, { -1, -1 } };
};
Q_DECLARE_TYPEINFO(QPathEdge, Q_PRIMITIVE_TYPE);
 
class QPathSegments
{
public:
    struct Intersection {
        qreal t;
        int vertex;
        int next;
 
        bool operator<(const Intersection &o) const {
            return t < o.t;
        }
    };
    friend class QTypeInfo<Intersection>;
 
    struct Segment {
        Segment(int pathId, int vertexA, int vertexB)
            : path(pathId)
            , va(vertexA)
            , vb(vertexB)
            , intersection(-1)
        {
        }
 
        int path;
 
        // vertices
        int va;
        int vb;
 
        // intersection index
        int intersection;
 
        QRectF bounds;
    };
    friend class QTypeInfo<Segment>;
 
 
    QPathSegments(int reserve);
 
    void setPath(const QPainterPath &path);
    void addPath(const QPainterPath &path);
 
    int intersections() const;
    int segments() const;
    int points() const;
 
    const Segment &segmentAt(int index) const;
    const QLineF lineAt(int index) const;
    const QRectF &elementBounds(int index) const;
    int pathId(int index) const;
 
    const QPointF &pointAt(int vertex) const;
    int addPoint(const QPointF &point);
 
    const Intersection *intersectionAt(int index) const;
    void addIntersection(int index, const Intersection &intersection);
 
    void mergePoints();
 
private:
    QDataBuffer<QPointF> m_points;
    QDataBuffer<Segment> m_segments;
    QDataBuffer<Intersection> m_intersections;
 
    int m_pathId;
};
Q_DECLARE_TYPEINFO(QPathSegments::Intersection, Q_PRIMITIVE_TYPE);
Q_DECLARE_TYPEINFO(QPathSegments::Segment, Q_PRIMITIVE_TYPE);
 
class Q_AUTOTEST_EXPORT QWingedEdge
{
public:
    struct TraversalStatus
    {
        int edge;
        QPathEdge::Traversal traversal;
        QPathEdge::Direction direction;
 
        void flipDirection();
        void flipTraversal();
 
        void flip();
    };
 
    QWingedEdge();
    QWingedEdge(const QPainterPath &subject, const QPainterPath &clip);
 
    void simplify();
    QPainterPath toPath() const;
 
    int edgeCount() const;
 
    QPathEdge *edge(int edge);
    const QPathEdge *edge(int edge) const;
 
    int vertexCount() const;
 
    int addVertex(const QPointF &p);
 
    QPathVertex *vertex(int vertex);
    const QPathVertex *vertex(int vertex) const;
 
    TraversalStatus next(const TraversalStatus &status) const;
 
    int addEdge(const QPointF &a, const QPointF &b);
    int addEdge(int vertexA, int vertexB);
 
    bool isInside(qreal x, qreal y) const;
 
    static QPathEdge::Traversal flip(QPathEdge::Traversal traversal);
    static QPathEdge::Direction flip(QPathEdge::Direction direction);
 
private:
    void intersectAndAdd();
 
    void printNode(int i, FILE *handle);
 
    void removeEdge(int ei);
 
    int insert(const QPathVertex &vertex);
    TraversalStatus findInsertStatus(int vertex, int edge) const;
 
    qreal delta(int vertex, int a, int b) const;
 
    QDataBuffer<QPathEdge> m_edges;
    QDataBuffer<QPathVertex> m_vertices;
 
    QList<qreal> m_splitPoints;
 
    QPathSegments m_segments;
};
 
inline QPathEdge::QPathEdge(int a, int b)
    : flag(0)
    , windingA(0)
    , windingB(0)
    , first(a)
    , second(b)
    , angle(0)
    , invAngle(0)
{
}
 
inline int QPathEdge::next(Traversal traversal, Direction direction) const
{
    return m_next[int(traversal)][int(direction)];
}
 
inline void QPathEdge::setNext(Traversal traversal, Direction direction, int next)
{
    m_next[int(traversal)][int(direction)] = next;
}
 
inline void QPathEdge::setNext(Direction direction, int next)
{
    m_next[0][int(direction)] = next;
    m_next[1][int(direction)] = next;
}
 
inline QPathEdge::Direction QPathEdge::directionTo(int vertex) const
{
    return first == vertex ? Backward : Forward;
}
 
inline int QPathEdge::vertex(Direction direction) const
{
    return direction == Backward ? first : second;
}
 
inline QPathVertex::QPathVertex(const QPointF &p, int e)
    : edge(e)
    , x(p.x())
    , y(p.y())
{
}
 
inline QPathVertex::operator QPointF() const
{
    return QPointF(x, y);
}
 
inline QPathSegments::QPathSegments(int reserve) :
    m_points(reserve),
    m_segments(reserve),
    m_intersections(reserve),
    m_pathId(0)
{
}
 
inline int QPathSegments::segments() const
{
    return m_segments.size();
}
 
inline int QPathSegments::points() const
{
    return m_points.size();
}
 
inline const QPointF &QPathSegments::pointAt(int i) const
{
    return m_points.at(i);
}
 
inline int QPathSegments::addPoint(const QPointF &point)
{
    m_points << point;
    return m_points.size() - 1;
}
 
inline const QPathSegments::Segment &QPathSegments::segmentAt(int index) const
{
    return m_segments.at(index);
}
 
inline const QLineF QPathSegments::lineAt(int index) const
{
    const Segment &segment = m_segments.at(index);
    return QLineF(m_points.at(segment.va), m_points.at(segment.vb));
}
 
inline const QRectF &QPathSegments::elementBounds(int index) const
{
    return m_segments.at(index).bounds;
}
 
inline int QPathSegments::pathId(int index) const
{
    return m_segments.at(index).path;
}
 
inline const QPathSegments::Intersection *QPathSegments::intersectionAt(int index) const
{
    const int intersection = m_segments.at(index).intersection;
    if (intersection < 0)
        return nullptr;
    else
        return &m_intersections.at(intersection);
}
 
inline int QPathSegments::intersections() const
{
    return m_intersections.size();
}
 
inline void QPathSegments::addIntersection(int index, const Intersection &intersection)
{
    m_intersections << intersection;
 
    Segment &segment = m_segments.at(index);
    if (segment.intersection < 0) {
        segment.intersection = m_intersections.size() - 1;
    } else {
        Intersection *isect = &m_intersections.at(segment.intersection);
 
        while (isect->next != 0)
            isect += isect->next;
 
        isect->next = (m_intersections.size() - 1) - (isect - m_intersections.data());
    }
}
 
inline int QWingedEdge::edgeCount() const
{
    return m_edges.size();
}
 
inline QPathEdge *QWingedEdge::edge(int edge)
{
    return edge < 0 ? nullptr : &m_edges.at(edge);
}
 
inline const QPathEdge *QWingedEdge::edge(int edge) const
{
    return edge < 0 ? nullptr : &m_edges.at(edge);
}
 
inline int QWingedEdge::vertexCount() const
{
    return m_vertices.size();
}
 
inline int QWingedEdge::addVertex(const QPointF &p)
{
    m_vertices << p;
    return m_vertices.size() - 1;
}
 
inline QPathVertex *QWingedEdge::vertex(int vertex)
{
    return vertex < 0 ? nullptr : &m_vertices.at(vertex);
}
 
inline const QPathVertex *QWingedEdge::vertex(int vertex) const
{
    return vertex < 0 ? nullptr : &m_vertices.at(vertex);
}
 
inline QPathEdge::Traversal QWingedEdge::flip(QPathEdge::Traversal traversal)
{
    return traversal == QPathEdge::RightTraversal ? QPathEdge::LeftTraversal : QPathEdge::RightTraversal;
}
 
inline void QWingedEdge::TraversalStatus::flipTraversal()
{
    traversal = QWingedEdge::flip(traversal);
}
 
inline QPathEdge::Direction QWingedEdge::flip(QPathEdge::Direction direction)
{
    return direction == QPathEdge::Forward ? QPathEdge::Backward : QPathEdge::Forward;
}
 
inline void QWingedEdge::TraversalStatus::flipDirection()
{
    direction = QWingedEdge::flip(direction);
}
 
inline void QWingedEdge::TraversalStatus::flip()
{
    flipDirection();
    flipTraversal();
}
 
QT_END_NAMESPACE
 
#endif // QPATHCLIPPER_P_H