/* Copyright (C) 1995 Aladdin Enterprises.  All rights reserved.
  
  This file is part of Aladdin Ghostscript.
  
  Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
  or distributor accepts any responsibility for the consequences of using it,
  or for whether it serves any particular purpose or works at all, unless he
  or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
  License (the "License") for full details.
  
  Every copy of Aladdin Ghostscript must include a copy of the License,
  normally in a plain ASCII text file named PUBLIC.  The License grants you
  the right to copy, modify and redistribute Aladdin Ghostscript, but only
  under certain conditions described in the License.  Among other things, the
  License requires that the copyright notice and this notice be preserved on
  all copies.
*/

/* gxpdash.c */
/* Dash expansion for paths */
#include "math_.h"
#include "gx.h"
#include "gsmatrix.h"			/* for gscoord.h */
#include "gscoord.h"
#include "gxfixed.h"
#include "gsline.h"
#include "gzline.h"
#include "gzpath.h"

/* Expand a dashed path into explicit segments. */
/* The path contains no curves. */
private int subpath_expand_dashes(P3(const subpath *, gx_path *,
				     const gs_imager_state *));
int
gx_path_expand_dashes(const gx_path *ppath_old, gx_path *ppath,
  const gs_imager_state *pis)
{	const subpath *psub;
	if ( gs_currentlineparams(pis)->dash.pattern_size == 0 )
	  return gx_path_copy(ppath_old, ppath, true);
	gx_path_init(ppath, ppath_old->memory);
	for ( psub = ppath_old->first_subpath; psub != 0;
	      psub = (const subpath *)psub->last->next
	    )
	  {	int code = subpath_expand_dashes(psub, ppath, pis);
		if ( code < 0 )
		  {	gx_path_release(ppath);
			return code;
		  }
	  }
	return 0;
}
private int
subpath_expand_dashes(const subpath *psub, gx_path *ppath,
  const gs_imager_state *pis)
{	const gx_dash_params *dash = &gs_currentlineparams(pis)->dash;
	const float *pattern = dash->pattern;
	int count, ink_on, index;
	float dist_left;
	fixed x0 = psub->pt.x, y0 = psub->pt.y;
	fixed x, y;
	const segment *pseg;
	int wrap = (dash->init_ink_on && psub->is_closed ? -1 : 0);
	int drawing = wrap;
	int code;
	if ( (code = gx_path_add_point(ppath, x0, y0)) < 0 )
		return code;
	/* To do the right thing at the beginning of a closed path, */
	/* we have to skip any initial line, and then redo it at */
	/* the end of the path.  Drawing = -1 while skipping, */
	/* 0 while drawing normally, and 1 on the second round. */
top:	count = dash->pattern_size;
	ink_on = dash->init_ink_on;
	index = dash->init_index;
	dist_left = dash->init_dist_left;
	x = x0, y = y0;
	pseg = (const segment *)psub;
	while ( (pseg = pseg->next) != 0 && pseg->type != s_start )
	   {	fixed sx = pseg->pt.x, sy = pseg->pt.y;
		fixed udx = sx - x, udy = sy - y;
		float length, dx, dy;
		float dist;
		if ( !(udx | udy) )	/* degenerate */
			dx = 0, dy = 0, length = 0;
		else
		   {	gs_point d;
			dx = udx, dy = udy;	/* scaled as fixed */
			gs_imager_idtransform(pis, dx, dy, &d);
			length = hypot(d.x, d.y) * (1 / (float)int2fixed(1));
		   }
		dist = length;
		while ( dist > dist_left )
		   {	/* We are using up the dash element */
			float fraction = dist_left / length;
			fixed nx = x + (fixed)(dx * fraction);
			fixed ny = y + (fixed)(dy * fraction);
			if ( ink_on )
			   {	if ( drawing >= 0 )
				  code = gx_path_add_line(ppath, nx, ny);
			   }
			else
			   {	if ( drawing > 0 ) return 0;	/* done */
				code = gx_path_add_point(ppath, nx, ny);
				drawing = 0;
			   }
			if ( code < 0 ) return code;
			dist -= dist_left;
			ink_on = !ink_on;
			if ( ++index == count ) index = 0;
			dist_left = pattern[index];
			x = nx, y = ny;
		   }
		dist_left -= dist;
		/* Handle the last dash of a segment. */
		if ( ink_on )
		   {	if ( drawing >= 0 )
			  code =
			    (pseg->type == s_line_close && drawing > 0 ?
			     gx_path_close_subpath(ppath) :
			     gx_path_add_line(ppath, sx, sy));
		   }
		else
		   {	if ( drawing > 0 ) return 0;	/* done */
			code = gx_path_add_point(ppath, sx, sy);
			drawing = 0;
		   }
		if ( code < 0 ) return code;
		x = sx, y = sy;
	   }
	/* Check for wraparound. */
	if ( wrap && drawing <= 0 )
	   {	/* We skipped some initial lines. */
		/* Go back and do them now. */
		drawing = 1;
		goto top;
	   }
	return 0;
}