qwt_compass_rose.cpp File Reference

#include <math.h>
#include <qpainter.h>
#include "qwt_math.h"
#include "qwt_painter.h"
#include "qwt_compass_rose.h"

Go to the source code of this file.

Functions
static QPoint	cutPoint (QPoint p11, QPoint p12, QPoint p21, QPoint p22)

---

Function Documentation

static QPoint cutPoint	(	QPoint	p11,
		QPoint	p12,
		QPoint	p21,
		QPoint	p22
	)		[static]

Definition at line 16 of file qwt_compass_rose.cpp.

References QuadProgPP::t().

Referenced by QwtSimpleCompassRose::drawRose().

{
    double dx1 = p12.x() - p11.x();
    double dy1 = p12.y() - p11.y();
    double dx2 = p22.x() - p21.x();
    double dy2 = p22.y() - p21.y();

    if ( dx1 == 0.0 && dx2 == 0.0 )
        return QPoint();

    if ( dx1 == 0.0 )
    {
        const double m = dy2 / dx2;
        const double t = p21.y() - m * p21.x();
        return QPoint(p11.x(), qRound(m * p11.x() + t));
    }

    if ( dx2 == 0 )
    {
        const double m = dy1 / dx1;
        const double t = p11.y() - m * p11.x();
        return QPoint(p21.x(), qRound(m * p21.x() + t));
    }

    const double m1 = dy1 / dx1;
    const double t1 = p11.y() - m1 * p11.x();

    const double m2 = dy2 / dx2;
    const double t2 = p21.y() - m2 * p21.x();

    if ( m1 == m2 )
        return QPoint();

    const double x = ( t2 - t1 ) / ( m1 - m2 );
    const double y = t1 + m1 * x;

    return QPoint(qRound(x), qRound(y));
}