common.cc

早期freebsd实现

// -*- C++ -*-
/* Copyright (C) 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
     Written by James Clark ([e-mail])

This file is part of groff.

groff 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, or (at your option) any later
version.

groff is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with groff; see the file COPYING.  If not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */

#include "pic.h"
#include "common.h"

// output a dashed circle as a series of arcs

void common_output::dashed_circle(const position &cent, double rad,
				  const line_type &lt)
{
  assert(lt.type == line_type::dashed);
  line_type slt = lt;
  slt.type = line_type::solid;
  double dash_angle = lt.dash_width/rad;
  int ndashes;
  double gap_angle;
  if (dash_angle >= M_PI/4.0) {
    if (dash_angle < M_PI/2.0) {
      gap_angle = M_PI/2.0 - dash_angle;
      ndashes = 4;
    }
    else if (dash_angle < M_PI) {
      gap_angle = M_PI - dash_angle;
      ndashes = 2;
    }
    else {
      circle(cent, rad, slt, -1.0);
      return;
    }
  }
  else {
    ndashes = 4*int(ceil(M_PI/(4.0*dash_angle)));
    gap_angle = (M_PI*2.0)/ndashes - dash_angle;
  }
  for (int i = 0; i < ndashes; i++) {
    double start_angle = i*(dash_angle+gap_angle) - dash_angle/2.0;
    solid_arc(cent, rad, start_angle, start_angle + dash_angle, lt);
  }
}

// output a dotted circle as a series of dots

void common_output::dotted_circle(const position &cent, double rad,
				  const line_type &lt)
{
  assert(lt.type == line_type::dotted);
  double gap_angle = lt.dash_width/rad;
  int ndots;
  if (gap_angle >= M_PI/2.0) {
    // always have at least 2 dots
    gap_angle = M_PI;
    ndots = 2;
  }
  else {
    ndots = 4*int(M_PI/(2.0*gap_angle));
    gap_angle = (M_PI*2.0)/ndots;
  }
  double ang = 0.0;
  for (int i = 0; i < ndots; i++, ang += gap_angle)
    dot(cent + position(cos(ang), sin(ang))*rad, lt);
}

// return non-zero iff we can compute a center

int compute_arc_center(const position &start, const position &cent,
		       const position &end, position *result)
{
  // This finds the point along the vector from start to cent that
  // is equidistant between start and end.
  distance c = cent - start;
  distance e = end - start;
  double n = c*e;
  if (n == 0.0)
    return 0;
  *result = start + c*((e*e)/(2.0*n));
  return 1;
}

// output a dashed arc as a series of arcs

void common_output::dashed_arc(const position &start, const position &cent,
			       const position &end, const line_type &lt)
{
  assert(lt.type == line_type::dashed);
  position c;
  if (!compute_arc_center(start, cent, end, &c)) {
    line(start, &end, 1, lt);
    return;
  }
  distance start_offset = start - c;
  distance end_offset = end - c;
  double start_angle = atan2(start_offset.y, start_offset.x);
  double end_angle = atan2(end_offset.y, end_offset.x);
  double rad = hypot(c - start);
  double dash_angle = lt.dash_width/rad;
  double total_angle = end_angle - start_angle;
  while (total_angle < 0)
    total_angle += M_PI + M_PI;
  if (total_angle <= dash_angle*2.0) {
    solid_arc(cent, rad, start_angle, end_angle, lt);
    return;
  }
  int ndashes = int((total_angle - dash_angle)/(dash_angle*2.0) + .5);
  double dash_and_gap_angle = (total_angle - dash_angle)/ndashes;
  for (int i = 0; i <= ndashes; i++)
    solid_arc(cent, rad, start_angle + i*dash_and_gap_angle,
	      start_angle + i*dash_and_gap_angle + dash_angle, lt);
}

// output a dotted arc as a series of dots

void common_output::dotted_arc(const position &start, const position &cent,
			       const position &end, const line_type &lt)
{
  assert(lt.type == line_type::dotted);
  position c;
  if (!compute_arc_center(start, cent, end, &c)) {
    line(start, &end, 1, lt);
    return;
  }
  distance start_offset = start - c;
  distance end_offset = end - c;
  double start_angle = atan2(start_offset.y, start_offset.x);
  double total_angle = atan2(end_offset.y, end_offset.x) - start_angle;
  while (total_angle < 0)
    total_angle += M_PI + M_PI;
  double rad = hypot(c - start);
  int ndots = int(total_angle/(lt.dash_width/rad) + .5);
  if (ndots == 0)
    dot(start, lt);
  else {
    for (int i = 0; i <= ndots; i++) {
      double a = start_angle + (total_angle*i)/ndots;
      dot(cent + position(cos(a), sin(a))*rad, lt);
    }
  }
}

void common_output::solid_arc(const position &cent, double rad,
			      double start_angle, double end_angle,
			      const line_type &lt)
{
  line_type slt = lt;
  slt.type = line_type::solid;
  arc(cent + position(cos(start_angle), sin(start_angle))*rad,
      cent,
      cent + position(cos(end_angle), sin(end_angle))*rad,
      slt);
}


void common_output::rounded_box(const position &cent, const distance &dim,
				double rad, const line_type &lt, double fill)
{
  if (fill >= 0.0)
    filled_rounded_box(cent, dim, rad, fill);
  switch (lt.type) {
  case line_type::invisible:
    break;
  case line_type::dashed:
    dashed_rounded_box(cent, dim, rad, lt);
    break;
  case line_type::dotted:
    dotted_rounded_box(cent, dim, rad, lt);
    break;
  case line_type::solid:
    solid_rounded_box(cent, dim, rad, lt);
    break;
  default:
    assert(0);
  }
}


void common_output::dashed_rounded_box(const position &cent,
				       const distance &dim, double rad,
				       const line_type &lt)
{
  line_type slt = lt;
  slt.type = line_type::solid;

  double hor_length = dim.x + (M_PI/2.0 - 2.0)*rad;
  int n_hor_dashes = int(hor_length/(lt.dash_width*2.0) + .5);
  double hor_gap_width = (n_hor_dashes != 0
			  ? hor_length/n_hor_dashes - lt.dash_width
			  : 0.0);

  double vert_length = dim.y + (M_PI/2.0 - 2.0)*rad;
  int n_vert_dashes = int(vert_length/(lt.dash_width*2.0) + .5);
  double vert_gap_width = (n_vert_dashes != 0
			   ? vert_length/n_vert_dashes - lt.dash_width
			   : 0.0);
  // Note that each corner arc has to be split into two for dashing,
  // because one part is dashed using vert_gap_width, and the other
  // using hor_gap_width.
  double offset = lt.dash_width/2.0;
  dash_arc(cent + position(dim.x/2.0 - rad, -dim.y/2.0 + rad), rad,
	   -M_PI/4.0, 0, slt, lt.dash_width, vert_gap_width, &offset);
  dash_line(cent + position(dim.x/2.0, -dim.y/2.0 + rad),
	    cent + position(dim.x/2.0, dim.y/2.0 - rad),
	    slt, lt.dash_width, vert_gap_width, &offset);
  dash_arc(cent + position(dim.x/2.0 - rad, dim.y/2.0 - rad), rad,
	   0, M_PI/4.0, slt, lt.dash_width, vert_gap_width, &offset);

  offset = lt.dash_width/2.0;
  dash_arc(cent + position(dim.x/2.0 - rad, dim.y/2.0 - rad), rad,
	   M_PI/4.0, M_PI/2, slt, lt.dash_width, hor_gap_width, &offset);
  dash_line(cent + position(dim.x/2.0 - rad, dim.y/2.0),
	    cent + position(-dim.x/2.0 + rad, dim.y/2.0),
	    slt, lt.dash_width, hor_gap_width, &offset);
  dash_arc(cent + position(-dim.x/2.0 + rad, dim.y/2.0 - rad), rad,
	   M_PI/2, 3*M_PI/4.0, slt, lt.dash_width, hor_gap_width, &offset);

  offset = lt.dash_width/2.0;
  dash_arc(cent + position(-dim.x/2.0 + rad, dim.y/2.0 - rad), rad,
	   3.0*M_PI/4.0, M_PI, slt, lt.dash_width, vert_gap_width, &offset);
  dash_line(cent + position(-dim.x/2.0, dim.y/2.0 - rad),
	    cent + position(-dim.x/2.0, -dim.y/2.0 + rad),
	    slt, lt.dash_width, vert_gap_width, &offset);
  dash_arc(cent + position(-dim.x/2.0 + rad, -dim.y/2.0 + rad), rad,
	   M_PI, 5.0*M_PI/4.0, slt, lt.dash_width, vert_gap_width, &offset);

  offset = lt.dash_width/2.0;
  dash_arc(cent + position(-dim.x/2.0 + rad, -dim.y/2.0 + rad), rad,
	   5*M_PI/4.0, 3*M_PI/2.0, slt, lt.dash_width, hor_gap_width, &offset);
  dash_line(cent + position(-dim.x/2.0 + rad, -dim.y/2.0),
	    cent + position(dim.x/2.0 - rad, -dim.y/2.0),
	    slt, lt.dash_width, hor_gap_width, &offset);
  dash_arc(cent + position(dim.x/2.0 - rad, -dim.y/2.0 + rad), rad,
	   3*M_PI/2, 7*M_PI/4, slt, lt.dash_width, hor_gap_width, &offset);