/* Copyright (C) 2001-2006 Artifex Software, Inc.
   All Rights Reserved.
  
   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/
   or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/

/* $Id: gxpdash.c 8250 2007-09-25 13:31:24Z giles $ */
/* Dash expansion for paths */
#include "math_.h"
#include "gx.h"
#include "gsmatrix.h"		/* for gscoord.h */
#include "gscoord.h"
#include "gxfixed.h"
#include "gxarith.h"
#include "gxistate.h"
#include "gsline.h"
#include "gzline.h"
#include "gzpath.h"

/* Expand a dashed path into explicit segments. */
/* The path contains no curves. */
static int subpath_expand_dashes(const subpath *, gx_path *,
				  const gs_imager_state *,
				  const gx_dash_params *);
int
gx_path_add_dash_expansion(const gx_path * ppath_old, gx_path * ppath,
			   const gs_imager_state * pis)
{
    const subpath *psub;
    const gx_dash_params *dash = &gs_currentlineparams(pis)->dash;
    int code = 0;

    if (dash->pattern_size == 0)
	return gx_path_copy(ppath_old, ppath);
    for (psub = ppath_old->first_subpath; psub != 0 && code >= 0;
	 psub = (const subpath *)psub->last->next
	)
	code = subpath_expand_dashes(psub, ppath, pis, dash);
    return code;
}

static int
subpath_expand_dashes(const subpath * psub, gx_path * ppath,
		   const gs_imager_state * pis, const gx_dash_params * dash)
{
    const float *pattern = dash->pattern;
    int count, index;
    bool ink_on;
    double elt_length;
    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;
    segment_notes notes = ~sn_not_first;
    const gx_line_params *pgs_lp = gs_currentlineparams_inline(pis);
    bool zero_length = true;
    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.  Note that drawing != 0 implies ink_on.
     */
  top:count = dash->pattern_size;
    ink_on = dash->init_ink_on;
    index = dash->init_index;
    elt_length = 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;
	double length, dx, dy;
	double scale = 1;
	double left;

	if (!(udx | udy)) {	/* degenerate */
	    if (pgs_lp->dot_length == 0 &&
		pgs_lp->cap != gs_cap_round) {
		/* From PLRM, stroke operator :
		   If a subpath is degenerate (consists of a single-point closed path 
		   or of two or more points at the same coordinates), 
		   stroke paints it only if round line caps have been specified */
		if (zero_length || pseg->type != s_line_close)
		    continue;
	    }
	    dx = 0, dy = 0, length = 0;
	} else {
  	    gs_point d;

	    zero_length = false;
	    dx = udx, dy = udy;	/* scaled as fixed */
	    gs_imager_idtransform(pis, dx, dy, &d);
	    length = hypot(d.x, d.y) * (1.0 / fixed_1);
	    if (gs_imager_currentdashadapt(pis)) {
		double reps = length / dash->pattern_length;

		scale = reps / ceil(reps);
		/* Ensure we're starting at the start of a */
		/* repetition.  (This shouldn't be necessary, */
		/* but it is.) */
		count = dash->pattern_size;
		ink_on = dash->init_ink_on;
		index = dash->init_index;
		elt_length = dash->init_dist_left * scale;
	    }
	}
	left = length;
	while (left > elt_length) {	/* We are using up the line segment. */
	    double fraction = elt_length / length;
	    fixed fx = (fixed) (dx * fraction);
	    fixed fy = (fixed) (dy * fraction);
	    fixed nx = x + fx;
	    fixed ny = y + fy;

	    if (ink_on) {
		if (drawing >= 0) {
		    if (left >= elt_length && any_abs(fx) + any_abs(fy) < fixed_half)
			code = gx_path_add_dash_notes(ppath, nx, ny, udx, udy, 
				notes & pseg->notes);
		    else
			code = gx_path_add_line_notes(ppath, nx, ny,
						  notes & pseg->notes);
		}
		notes |= sn_not_first;
	    } else {
		if (drawing > 0)	/* done */
		    return 0;
		code = gx_path_add_point(ppath, nx, ny);
		notes &= ~sn_not_first;
		drawing = 0;
	    }
	    if (code < 0)
		return code;
	    left -= elt_length;
	    ink_on = !ink_on;
	    if (++index == count)
		index = 0;
	    elt_length = pattern[index] * scale;
	    x = nx, y = ny;
	}
	elt_length -= left;
	/* Handle the last dash of a segment. */
      on:if (ink_on) {
	    if (drawing >= 0) {
		if (pseg->type == s_line_close && drawing > 0)
		    code = gx_path_close_subpath_notes(ppath,
						 notes & pseg->notes);
		else if (any_abs(sx - x) + any_abs(sy - y) < fixed_half)
		    code = gx_path_add_dash_notes(ppath, sx, sy, udx, udy, 
			    notes & pseg->notes);
		else
		    code = gx_path_add_line_notes(ppath, sx, sy,
					notes & pseg->notes);
		notes |= sn_not_first;
	    }
	} else {
	    code = gx_path_add_point(ppath, sx, sy);
	    notes &= ~sn_not_first;
	    if (elt_length < fixed2float(fixed_epsilon) &&
		(pseg->next == 0 || pseg->next->type == s_start || elt_length == 0)) {		
				/*
				 * Ink is off, but we're within epsilon of the end
				 * of the dash element.  
				 * "Stretch" a little so we get a dot.
				 * Also if the next dash pattern is zero length,
				 * use the last segment orientation.
				 */
		double elt_length1;

		if (code < 0)
		    return code;
		if (++index == count)
		    index = 0;
		elt_length1 = pattern[index] * scale;
		if (pseg->next == 0 || pseg->next->type == s_start) {
		    elt_length = elt_length1;
		    left = 0;
		    ink_on = true;
		    goto on;
		}
		/* Looking ahead one dash pattern element.
		   If it is zero length, apply to the current segment 
		   (at its end). */
		if (elt_length1 == 0) {
		    left = 0;
		    code = gx_path_add_dash_notes(ppath, sx, sy, udx, udy,
				    notes & pseg->notes);
		    if (++index == count)
			index = 0;
		    elt_length = pattern[index] * scale;
		    ink_on = false;
		} else if (--index == 0) {
		    /* Revert lookahead. */
		    index = count - 1;
		}
	    }
	    if (drawing > 0)	/* done */
		return code;
	    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;
}
