source: trunk/src/gui/painting/qpolygonclipper_p.h@ 986

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#ifndef QPOLYGONCLIPPER_P_H
#define QPOLYGONCLIPPER_P_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of other Qt classes.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include "private/qdatabuffer_p.h"

QT_BEGIN_NAMESPACE

/* based on sutherland-hodgman line-by-line clipping, as described in
   Computer Graphics and Principles */
template <typename InType, typename OutType, typename CastType> class QPolygonClipper
{
public:
    QPolygonClipper() :
        buffer1(0), buffer2(0)
    {
        x1 = y1 = x2 = y2 = 0;
    }

    ~QPolygonClipper()
    {
    }

    void setBoundingRect(const QRect bounds)
    {
        x1 = bounds.x();
        x2 = bounds.x() + bounds.width();
        y1 = bounds.y();
        y2 = bounds.y() + bounds.height();
    }

    QRect boundingRect()
    {
        return QRect(QPoint(x1, y1), QPoint(x2, y2));
    }

    inline OutType intersectLeft(const OutType &p1, const OutType &p2)
    {
        OutType t;
        qreal dy = (p1.y - p2.y) / qreal(p1.x - p2.x);
        t.x = x1;
        t.y = static_cast<CastType>(p2.y + (x1 - p2.x) * dy);
        return t;
    }


    inline OutType intersectRight(const OutType &p1, const OutType &p2)
    {
        OutType t;
        qreal dy = (p1.y - p2.y) / qreal(p1.x - p2.x);
        t.x = x2;
        t.y = static_cast<CastType>(p2.y + (x2 - p2.x) * dy);
        return t;
    }


    inline OutType intersectTop(const OutType &p1, const OutType &p2)
    {
        OutType t;
        qreal dx = (p1.x - p2.x) / qreal(p1.y - p2.y);
        t.x = static_cast<CastType>(p2.x + (y1 - p2.y) * dx);
        t.y = y1;
        return t;
    }


    inline OutType intersectBottom(const OutType &p1, const OutType &p2)
    {
        OutType t;
        qreal dx = (p1.x - p2.x) / qreal(p1.y - p2.y);
        t.x = static_cast<CastType>(p2.x + (y2 - p2.y) * dx);
        t.y = y2;
        return t;
    }


    void clipPolygon(const InType *inPoints, int inCount, OutType **outPoints, int *outCount,
                     bool closePolygon = true)