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Sourcecode: rosegarden version File versions

spline.cpp

// -*- c-basic-offset: 4 -*-

/*
    Rosegarden-4
    A sequencer and musical notation editor.

    This program is Copyright 2000-2006
        Guillaume Laurent   <glaurent@telegraph-road.org>,
        Chris Cannam        <cannam@all-day-breakfast.com>,
        Richard Bown        <bownie@bownie.com>

    The moral right of the authors to claim authorship of this work
    has been asserted.

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/


#include "spline.h"


Spline::PointList *
Spline::calculate(const QPoint &s, const QPoint &f, const PointList &cp,
              QPoint &topLeft, QPoint &bottomRight)
{
    if (cp.size() < 2) return 0;

    int i;
    PointList *acc = new PointList();
    QPoint p(s);

    topLeft = bottomRight = QPoint(0, 0);

    for (i = 1; i < cp.size(); ++i) {
      
      QPoint c(cp[i-1]);
      
      int x = (c.x() + cp[i].x()) / 2;
      int y = (c.y() + cp[i].y()) / 2;
      QPoint n(x, y);

      calculateSegment(acc, p, n, c, topLeft, bottomRight);

      p = n;
    }

    calculateSegment(acc, p, f, cp[i-1], topLeft, bottomRight);

    return acc;
}


void
Spline::calculateSegment(PointList *acc,
                   const QPoint &s, const QPoint &f, const QPoint &c,
                   QPoint &topLeft, QPoint &bottomRight)
{
    int x, y, n;

    x = c.x() - s.x();
    y = c.y() - s.y();

    if (x < 0) x  = -x;
    if (y < 0) y  = -y;
    if (x > y) n  =  x;
    else       n  =  y;

    x = f.x() - c.x();
    y = f.y() - c.y();

    if (x < 0) x  = -x;
    if (y < 0) y  = -y;
    if (x > y) n +=  x;
    else       n +=  y;

    calculateSegmentSub(acc, s, f, c, n, topLeft, bottomRight);
}


void
Spline::calculateSegmentSub(PointList *acc,
                      const QPoint &s, const QPoint &f, const QPoint &c,
                      int n, QPoint &topLeft, QPoint &bottomRight)
{
    double ax = (double)(f.x() + s.x() - 2 * c.x()) / (double)n;
    double ay = (double)(f.y() + s.y() - 2 * c.y()) / (double)n;

    double bx = 2.0 * (double)(c.x() - s.x());
    double by = 2.0 * (double)(c.y() - s.y());

    for (int m = 0; m <= n; ++m) {

      int x = s.x() + (int)((m * ((double)m * ax + bx)) / n);
      int y = s.y() + (int)((m * ((double)m * ay + by)) / n);
      
      if (x < topLeft.x()) topLeft.setX(x);
      if (y < topLeft.y()) topLeft.setY(y);

      if (x > bottomRight.x()) bottomRight.setX(x);
      if (y > bottomRight.y()) bottomRight.setY(y);

      acc->push_back(QPoint(x, y));
    }
}


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