Russian Qt Forum

C++ (Qt)
#define PI 3.141592f
 
struct CArcGen {
 CArcGen( void );
 void CreatePolys( int steps, QVector <QPolygonF> & poly ) const;
 
 qreal mBegAngle;  // начальный угол в радианах
 qreal mEndAngle;  // конечный угол в радианах
 QPointF mCenter;  // центр
 QPointF mRadIn, mRadOut;  // внешний и внутренний радиусы по x и у
};
 
CArcGen::CArcGen( void ) : 
 mBegAngle(0.0f),
 mEndAngle(PI / 2),
 mRadOut(100, 100)
{
}
 
void CArcGen::CreatePolys( int steps, QVector <QPolygonF> & poly ) const
{
 steps = qMax(steps, 1);
 qreal delta = (mEndAngle - mBegAngle) / steps;
 qreal angle = mAngleBeg;
 qreal cos1 = cos(angle);
 qreal sin1 = sin(angle);
 
 for (int i = 0; i < steps; ++i) {
  angle += delta;
  qreal cos2 = cos(angle);
  qreal sin2 = sin(angle);
 
  poly.push_back(QPolygonF());
  QPolygonF & dst = poly.back();
 
  dst.push_back(QPointF(mRadOut.x() * cos1, mRadOut.y() * sin1));
  dst.push_back(QPointF(mRadOut.x() * cos2, mRadOut.y() * sin2));
  dst.push_back(QPointF(mRadIn.x() * cos2, mRadIn.y() * sin2));
  dst.push_back(QPointF(mRadIn.x() * cos1, mRadIn.y() * sin1));
 
  dst.translate(mCenter);
 
  cos1 = cos2; 
  sin1 = sin2;
 }
}
 
 

C++ (Qt)
QList<QPolygonF> QPainterPath::toFillPolygons ( const QTransform & matrix ) const