path: root/gs/src/gxfilltr.h

/* 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.
*/

/* $Id$ */
/* Configurable algorithm for decomposing a spot into trapezoids. */

/*
 * Since we need several statically defined variants of this algorithm,
 * we store it in .h file and include it several times into gxfill.c .
 * Configuration macros (template arguments) are :
 * 
 *  IS_SPOTAN - is the target device a spot analyzer ("spotan").
 *  PSEUDO_RASTERIZATION - use pseudo-rasterization.
 *  SMART_WINDING - even-odd filling rule for each contour independently.
 *  FILL_ADJUST - fill adjustment is not zero
 *  FILL_DIRECT - See LOOP_FILL_RECTANGLE_DIRECT.
 *  TEMPLATE_spot_into_trapezoids - the name of the procedure to generate.
 *  ADVANCE_WINDING(inside, alp, ll) - a macro for advancing the winding counter.
 *  INSIDE_PATH_P(inside, rule) - a macro for checking the winding rule.
*/

/* ---------------- Trapezoid decomposition loop ---------------- */

/* Takes lines off of y_list and adds them to */
/* x_list as needed.  band_mask limits the size of each band, */
/* by requiring that ((y1 - 1) & band_mask) == (y0 & band_mask). */
private int
TEMPLATE_spot_into_trapezoids (line_list *ll, fixed band_mask)
{
    const fill_options fo = *ll->fo;
    int rule = fo.rule;
    const fixed y_limit = fo.ymax;
    active_line *yll = ll->y_list;
    fixed y;
    int code;
    const bool all_bands = fo.is_spotan;

    if (yll == 0)
	return 0;		/* empty list */
    y = yll->start.y;		/* first Y value */
    ll->x_list = 0;
    ll->x_head.x_current = min_fixed;	/* stop backward scan */
    ll->margin_set0.y = fixed_pixround(y) - fixed_half;
    ll->margin_set1.y = fixed_pixround(y) - fixed_1 - fixed_half;
    while (1) {
	fixed y1;
	active_line *alp, *plp = NULL;
	bool covering_pixel_centers;

	INCR(iter);
	/* Move newly active lines from y to x list. */
	while (yll != 0 && yll->start.y == y) {
	    active_line *ynext = yll->next;	/* insert smashes next/prev links */

	    ll->y_list = ynext;
	    if (ll->y_line == yll)
		ll->y_line = ynext;
	    if (ynext != NULL)
		ynext->prev = NULL;
	    if (yll->direction == DIR_HORIZONTAL) {
		if (!PSEUDO_RASTERIZATION) {
		    /*
		     * This is a hack to make sure that isolated horizontal
		     * lines get stroked.
		     */
		    int yi = fixed2int_pixround(y - (!FILL_ADJUST ? 0 : fo.adjust_below));
		    int xi, wi;

		    if (yll->start.x <= yll->end.x) {
			xi = fixed2int_pixround(yll->start.x - (!FILL_ADJUST ? 0 : fo.adjust_left));
			wi = fixed2int_pixround(yll->end.x + (!FILL_ADJUST ? 0 : fo.adjust_right)) - xi;
		    } else {
			xi = fixed2int_pixround(yll->end.x - (!FILL_ADJUST ? 0 : fo.adjust_left));
			wi = fixed2int_pixround(yll->start.x + (!FILL_ADJUST ? 0 : fo.adjust_right)) - xi;
		    }
		    VD_RECT(xi, yi, wi, 1, VD_TRAP_COLOR);
		    code = LOOP_FILL_RECTANGLE_DIRECT(&fo, xi, yi, wi, 1);
		    if (code < 0)
			return code;
		} else if (PSEUDO_RASTERIZATION)
		    insert_h_new(yll, ll);
	    } else
		insert_x_new(yll, ll);
	    yll = ynext;
	}
	/* Mustn't leave by Y before process_h_segments. */
	if (ll->x_list == 0) {	/* No active lines, skip to next start */
	    if (yll == 0)
		break;		/* no lines left */
	    /* We don't close margin set here because the next set
	     * may fall into same window. */
	    y = yll->start.y;
	    ll->h_list1 = ll->h_list0;
	    ll->h_list0 = 0;
	    continue;
	}
	if (vd_enabled) {
	    vd_circle(0, y, 3, RGB(255, 0, 0));
	    y += 0; /* Just a good place for a debugger breakpoint */
	}
	/* Find the next evaluation point. */
	/* Start by finding the smallest y value */
	/* at which any currently active line ends */
	/* (or the next to-be-active line begins). */
	y1 = (yll != 0 ? yll->start.y : ll->y_break);
	/* Make sure we don't exceed the maximum band height. */
	{
	    fixed y_band = y | ~band_mask;

	    if (y1 > y_band)
		y1 = y_band + 1;
	}
	for (alp = ll->x_list; alp != 0; alp = alp->next) {
	    if (alp->end.y < y1)
		y1 = alp->end.y;
	}
#	ifdef DEBUG
	    if (gs_debug_c('F')) {
		dlprintf2("[F]before loop: y=%f y1=%f:\n",
			  fixed2float(y), fixed2float(y1));
		print_line_list(ll->x_list);
	    }
#	endif
	if (y == y1) {
	    code = process_h_segments(ll, y);
	    if (code < 0)
		return code;
	    {	int code1 = move_al_by_y(ll, y1);
		if (code1 < 0)
		    return code1;
	    }
	    if (code > 0) {
		yll = ll->y_list; /* add_y_line_aux in process_h_segments changes it. */
		continue;
	    }

	}
	if (y >= y_limit)
	    break;
	/* Now look for line intersections before y1. */
	covering_pixel_centers = COVERING_PIXEL_CENTERS(y, y1, 
			    (!FILL_ADJUST ? 0 : fo.adjust_below), 
			    (!FILL_ADJUST ? 0 : fo.adjust_above));
	if (y != y1) {
	    intersect_al(ll, y, &y1, (covering_pixel_centers ? 1 : -1), all_bands); /* May change y1. */
	    covering_pixel_centers = COVERING_PIXEL_CENTERS(y, y1, 
			    (!FILL_ADJUST ? 0 : fo.adjust_below), 
			    (!FILL_ADJUST ? 0 : fo.adjust_above));
	}
	/* Prepare dropout prevention. */
	if (PSEUDO_RASTERIZATION) {
	    code = start_margin_set(fo.dev, ll, y1);
	    if (code < 0)
		return code;
	}
	/* Fill a multi-trapezoid band for the active lines. */
	if (covering_pixel_centers || all_bands) {
	    int inside = 0;
	    active_line *flp = NULL;

	    if (SMART_WINDING)
		memset(ll->windings, 0, sizeof(ll->windings[0]) * ll->contour_count);
	    INCR(band);
	    /* Generate trapezoids */
	    for (alp = ll->x_list; alp != 0; alp = alp->next) {
		int code;

		print_al("step", alp);
		INCR(band_step);
		if (!INSIDE_PATH_P(inside, rule)) { 	/* i.e., outside */
		    ADVANCE_WINDING(inside, alp, ll);
		    if (INSIDE_PATH_P(inside, rule))	/* about to go in */
			flp = alp;
		    continue;
		}
		/* We're inside a region being filled. */
		ADVANCE_WINDING(inside, alp, ll);
		if (INSIDE_PATH_P(inside, rule))	/* not about to go out */
		    continue;
		/* We just went from inside to outside, 
		   chech whether we'll immediately go inside. */
		if (alp->next != NULL &&
		    alp->x_current == alp->next->x_current &&
		    alp->x_next == alp->next->x_next) {
		    /* If the next trapezoid contacts this one, unite them.
		       This simplifies data for the spot analyzer
		       and reduces the number of trapezoids in the rasterization.
		       Note that the topology possibly isn't exactly such
		       as we generate by this uniting :
		       Due to arithmetic errors in x_current, x_next
		       we can unite things, which really are not contacting.
		       But this level of the topology precision is enough for 
		       the glyph grid fitting. 
		       Also note that 
		       while a rasterization with dropout prevention 
		       it may cause a shift when choosing a pixel 
		       to paint with a narrow trapezoid. */
		    alp = alp->next;
		    ADVANCE_WINDING(inside, alp, ll);
		    continue;
		}
		/* We just went from inside to outside, so fill the region. */
		INCR(band_fill);
		if (FILL_ADJUST && !(flp->end.x == flp->start.x && alp->end.x == alp->start.x) && 
		    (fo.adjust_below | fo.adjust_above) != 0) {
		    /* Assuming pseudo_rasterization = false. */
		    if (FILL_DIRECT)
			code = slant_into_trapezoids__fd(ll, flp, alp, y, y1);
		    else
			code = slant_into_trapezoids__nd(ll, flp, alp, y, y1);
		} else {
		    fixed ybot = max(y, fo.pbox->p.y);
		    fixed ytop = min(y1, fo.pbox->q.y);

		    if (IS_SPOTAN) {
			/* We can't pass data through the device interface because 
			   we need to pass segment pointers. We're unhappy of that. */
			code = gx_san_trap_store((gx_device_spot_analyzer *)fo.dev, 
			    y, y1, flp->x_current, alp->x_current, flp->x_next, alp->x_next, 
			    flp->pseg, alp->pseg, flp->direction, alp->direction);
		    } else {
			if (flp->end.x == flp->start.x && alp->end.x == alp->start.x) {
			    if (FILL_ADJUST) {
				ybot = max(y  - fo.adjust_below, fo.pbox->p.y);
				ytop = min(y1 + fo.adjust_above, fo.pbox->q.y);
			    }
			    if (ytop > ybot) {
				int yi = fixed2int_pixround(ybot);
				int hi = fixed2int_pixround(ytop) - yi;
				int xli = fixed2int_var_pixround(flp->end.x - (!FILL_ADJUST ? 0 : fo.adjust_left));
				int xi  = fixed2int_var_pixround(alp->end.x + (!FILL_ADJUST ? 0 : fo.adjust_right));

				if (PSEUDO_RASTERIZATION && xli == xi) {
				    /*
				    * The scan is empty but we should paint something 
				    * against a dropout. Choose one of two pixels which 
				    * is closer to the "axis".
				    */
				    fixed xx = int2fixed(xli);

				    if (xx - flp->end.x < alp->end.x - xx)
					++xi;
				    else
					--xli;
				}
				vd_rect(flp->end.x, y, alp->end.x, y1, 1, VD_TRAP_COLOR);
				code = LOOP_FILL_RECTANGLE_DIRECT(&fo, xli, yi, xi - xli, hi);
			    } else
				code = 0;
			} else if (ybot < ytop) {
			    gs_fixed_edge le, re;

			    le.start = flp->start;
			    le.end = flp->end;
			    re.start = alp->start;
			    re.end = alp->end;
			    vd_quad(flp->x_current, ybot, alp->x_current, ybot, alp->x_next, ytop, flp->x_next, ytop, 1, VD_TRAP_COLOR);
			    if (PSEUDO_RASTERIZATION) {
				int flags = ftf_pseudo_rasterization;

				if (flp->start.x == alp->start.x && flp->start.y == y && alp->start.y == y)
				    flags |= ftf_peak0;
				if (flp->end.x == alp->end.x && flp->end.y == y1 && alp->end.y == y1)
				    flags |= ftf_peak0;
				if (FILL_DIRECT)
				    code = gx_fill_trapezoid_cf_fd(fo.dev, &le, &re, ybot, ytop, flags, fo.pdevc, fo.lop);
				else
				    code = gx_fill_trapezoid_cf_nd(fo.dev, &le, &re, ybot, ytop, flags, fo.pdevc, fo.lop);
			    } else
				code = fo.fill_trap(fo.dev, 
					&le, &re, ybot, ytop, false, fo.pdevc, fo.lop);
			} else
			    code = 0;
		    }
		    if (PSEUDO_RASTERIZATION) {
			if (code < 0)
			    return code;
			code = complete_margin(ll, flp, alp, y, y1);
			if (code < 0)
			    return code;
			code = margin_interior(ll, flp, alp, y, y1);
			if (code < 0)
			    return code;
			code = add_margin(ll, flp, alp, y, y1);
			if (code < 0)
			    return code;
			code = process_h_lists(ll, plp, flp, alp, y, y1);
			plp = alp;
		    }
		}
		if (code < 0)
		    return code;
	    }
	} else {
	    /* No trapezoids generation needed. */
	    if (PSEUDO_RASTERIZATION) {
		/* Process dropouts near trapezoids. */
		active_line *flp = NULL;
		int inside = 0;

		if (SMART_WINDING)
		    memset(ll->windings, 0, sizeof(ll->windings[0]) * ll->contour_count);
		for (alp = ll->x_list; alp != 0; alp = alp->next) {
		    if (!INSIDE_PATH_P(inside, rule)) {		/* i.e., outside */
			ADVANCE_WINDING(inside, alp, ll);
			if (INSIDE_PATH_P(inside, rule))	/* about to go in */
			    flp = alp;
			continue;
		    }
		    /* We're inside a region being filled. */
		    ADVANCE_WINDING(inside, alp, ll);
		    if (INSIDE_PATH_P(inside, rule))	/* not about to go out */
			continue;
		    code = continue_margin(ll, flp, alp, y, y1);
		    if (code < 0)
			return code;
		    code = process_h_lists(ll, plp, flp, alp, y, y1);
		    plp = alp;
		    if (code < 0)
			return code;
		}
	    }
	}
	if (PSEUDO_RASTERIZATION && plp != 0) {
	    code = process_h_lists(ll, plp, 0, 0, y, y1);
	    if (code < 0)
		return code;
	}
	code = move_al_by_y(ll, y1);
	if (code < 0)
	    return code;
	ll->h_list1 = ll->h_list0;
	ll->h_list0 = 0;
	y = y1;
    }
    if (PSEUDO_RASTERIZATION) {
	code = process_h_lists(ll, 0, 0, 0, y, y + 1 /*stub*/);
	if (code < 0)
	    return code;
	code = close_margins(fo.dev, ll, &ll->margin_set1);
	if (code < 0)
	    return code;
	return close_margins(fo.dev, ll, &ll->margin_set0);
    } 
    return 0;
}