qt_widget_conic_arc_2.h

来自「CGAL is a collaborative effort of severa」· C头文件 代码 · 共 104 行

// Copyright (c) 2001  Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you may redistribute it under
// the terms of the Q Public License version 1.0.
// See the file LICENSE.QPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $Source: /CVSROOT/CGAL/Packages/Arrangement/include/CGAL/IO/Qt_widget_Conic_arc_2.h,v $
// $Revision: 1.3 $ $Date: 2004/07/21 09:20:12 $
// $Name:  $
//
// Author(s)     : Efi Fogel <[e-mail]>

#ifndef CGAL_QT_WIDGET_CONIC_ARC_2_H
#define CGAL_QT_WIDGET_CONIC_ARC_2_H

#include <CGAL/IO/Qt_widget.h>
#include <CGAL/Arrangement_2/Conic_arc_2.h>

CGAL_BEGIN_NAMESPACE

template <class Int_kernel, class Alg_kernel>
Qt_widget & operator<< (Qt_widget & ws, 
		        const Conic_arc_2<Int_kernel, Alg_kernel>& cv)
{
  typedef typename Alg_kernel::FT                               CoNT;
  typedef typename Conic_arc_2<Int_kernel, Alg_kernel>::Point_2 Point_2;

  // Get the co-ordinates of the curve's source and target.
  double sx = CGAL::to_double(cv.source().x()),
         sy = CGAL::to_double(cv.source().y()),
         tx = CGAL::to_double(cv.target().x()),
         ty = CGAL::to_double(cv.target().y());

  if (cv.is_segment()) {
    // The curve is a segment - simply draw it.
    ws.get_painter().drawLine(ws.x_pixel(sx), ws.y_pixel(sy),
                              ws.x_pixel(tx), ws.y_pixel(ty));
    return (ws); 
  }

  // Draw a non-linear conic arc.
  if (cv.is_x_monotone()) 
  {
    // If the curve is monotone, than its source and its target has the
    // extreme x co-ordinates on this curve.
    bool is_source_left = (sx < tx);
    int  x_min = is_source_left ? ws.x_pixel(sx) : ws.x_pixel(tx);
    int  x_max = is_source_left ? ws.x_pixel(tx) : ws.x_pixel(sx);
    double prev_y = is_source_left ? sy : ty;
    double end_x = is_source_left ? tx : sx;
    double end_y = is_source_left ? ty : sy;
    double curr_x, curr_y;
    int x;

    Point_2   ps[2];
    Point_2   q;
    int       nps;

    ws.get_painter().moveTo(x_min, ws.y_pixel(prev_y));
      
    for (x = x_min + 1; x < x_max; x++)
    {
      curr_x = ws.x_real(x);
      q = Point_2 (CoNT(curr_x), CoNT(0));
      nps = cv.get_points_at_x (q, ps);

      if (nps == 1)
      {
        curr_y = CGAL::to_double(ps[0].y());
        ws.get_painter().lineTo(x, ws.y_pixel(curr_y));
      }
    }

    ws.get_painter().lineTo(ws.x_pixel(end_x), ws.y_pixel(end_y));
    return (ws); 
  }
  else
  {
    // Break the arc into x-monotone sub-curves and draw each one separately.
    Arr_conic_traits_2<Int_kernel, Alg_kernel>       traits; 
    std::list<Conic_arc_2<Int_kernel, Alg_kernel> >  x_mon_curves;
    typename std::list<Conic_arc_2<Int_kernel, Alg_kernel> >::iterator xit;

    traits.curve_make_x_monotone (cv,
				  std::back_inserter (x_mon_curves));

    for (xit = x_mon_curves.begin(); xit != x_mon_curves.end(); xit++)
      ws << *xit;
  }

  return (ws); 
}

CGAL_END_NAMESPACE

#endif