agg/source/agg_vpgen_clip_polyline.cpp

   1 //----------------------------------------------------------------------------
   2 // Anti-Grain Geometry - Version 2.3
   3 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
   4 //
   5 // Permission to copy, use, modify, sell and distribute this software
   6 // is granted provided this copyright notice appears in all copies.
   7 // This software is provided "as is" without express or implied
   8 // warranty, and with no claim as to its suitability for any purpose.
   9 //
  10 //----------------------------------------------------------------------------
  11 // Contact: mcseem@antigrain.com
  12 //          mcseemagg@yahoo.com
  13 //          http://www.antigrain.com
  14 //----------------------------------------------------------------------------
  15
  16 #include <math.h>
  17 #include "agg_vpgen_clip_polyline.h"
  18
  19 namespace agg
  20 {
  21     static double clip_epsilon = 1e-10;
  22
  23
  24     //----------------------------------------------------------------------------
  25     void vpgen_clip_polyline::reset()
  26     {
  27         m_vertex = 0;
  28         m_num_vertices = 0;
  29     }
  30
  31     //----------------------------------------------------------------------------
  32     void vpgen_clip_polyline::move_to(double x, double y)
  33     {
  34         m_vertex = 0;
  35         m_num_vertices = 0;
  36         m_f1 = clipping_flags(x, y);
  37         if(m_f1 == 0)
  38         {
  39             m_x[0] = x;
  40             m_y[0] = y;
  41             m_cmd[0] = path_cmd_move_to;
  42             m_num_vertices = 1;
  43         }
  44         m_x1 = x;
  45         m_y1 = y;
  46     }
  47
  48
  49     //----------------------------------------------------------------------------
  50     bool vpgen_clip_polyline::move_point(double& x, double& y, unsigned& flags)
  51     {
  52        double bound;
  53
  54        if(flags & (clip_x1 | clip_x2))
  55        {
  56            bound = (flags & clip_x1) ? m_clip_box.x1 : m_clip_box.x2;
  57            y = (bound - m_x1) * (m_y2 - m_y1) / (m_x2 - m_x1) + m_y1;
  58            x = bound;
  59            flags = clipping_flags_y(y);
  60        }
  61        if(fabs(m_y2 - m_y1) < clip_epsilon && fabs(m_x2 - m_x1) < clip_epsilon)
  62        {
  63            return false;
  64        }
  65        if(flags & (clip_y1 | clip_y2))
  66        {
  67            bound = (flags & clip_y1) ? m_clip_box.y1 : m_clip_box.y2;
  68            x = (bound - m_y1) * (m_x2 - m_x1) / (m_y2 - m_y1) + m_x1;
  69            y = bound;
  70        }
  71        flags = 0;
  72        return true;
  73     }
  74
  75     //----------------------------------------------------------------------------
  76     void vpgen_clip_polyline::clip_line_segment()
  77     {
  78         if((m_f1 & m_f2) == 0)
  79         {
  80             if(m_f1)
  81             {
  82                 if(!move_point(m_x1, m_y1, m_f1)) return;
  83                 if(m_f1) return;
  84                 m_x[0] = m_x1;
  85                 m_y[0] = m_y1;
  86                 m_cmd[0] = path_cmd_move_to;
  87                 m_num_vertices = 1;
  88             }
  89             if(m_f2)
  90             {                    // Move Point 2
  91                 if(!move_point(m_x2, m_y2, m_f2)) return;
  92             }
  93             m_x[m_num_vertices] = m_x2;
  94             m_y[m_num_vertices] = m_y2;
  95             m_cmd[m_num_vertices++] = path_cmd_line_to;
  96         }
  97     }
  98
  99
 100
 101     //----------------------------------------------------------------------------
 102     void vpgen_clip_polyline::line_to(double x, double y)
 103     {
 104         m_vertex = 0;
 105         m_num_vertices = 0;
 106         unsigned f = m_f2 = clipping_flags(m_x2 = x, m_y2 = y);
 107
 108         if(m_f2 == m_f1)
 109         {
 110             if(m_f2 == 0)
 111             {
 112                 m_x[0] = x;
 113                 m_y[0] = y;
 114                 m_cmd[0] = path_cmd_line_to;
 115                 m_num_vertices = 1;
 116             }
 117         }
 118         else
 119         {
 120             clip_line_segment();
 121         }
 122
 123         m_f1 = f;
 124         m_x1 = x;
 125         m_y1 = y;
 126     }
 127
 128
 129     //----------------------------------------------------------------------------
 130     unsigned vpgen_clip_polyline::vertex(double* x, double* y)
 131     {
 132         if(m_vertex < m_num_vertices)
 133         {
 134             *x = m_x[m_vertex];
 135             *y = m_y[m_vertex];
 136             return m_cmd[m_vertex++];
 137         }
 138         return path_cmd_stop;
 139     }
 140
 141
 142 }