cairo-path-fill.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2002 University of Southern California
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is University of Southern
 * California.
 *
 * Contributor(s):
 *	Carl D. Worth <[e-mail]>
 */

#include "cairoint.h"

typedef struct cairo_filler {
    double tolerance;
    cairo_traps_t *traps;

    cairo_point_t current_point;

    cairo_polygon_t polygon;
} cairo_filler_t;

static void
_cairo_filler_init (cairo_filler_t *filler, double tolerance, cairo_traps_t *traps);

static void
_cairo_filler_fini (cairo_filler_t *filler);

static cairo_status_t
_cairo_filler_move_to (void *closure, cairo_point_t *point);

static cairo_status_t
_cairo_filler_line_to (void *closure, cairo_point_t *point);

static cairo_status_t
_cairo_filler_curve_to (void *closure,
			cairo_point_t *b,
			cairo_point_t *c,
			cairo_point_t *d);

static cairo_status_t
_cairo_filler_close_path (void *closure);

static void
_cairo_filler_init (cairo_filler_t *filler, double tolerance, cairo_traps_t *traps)
{
    filler->tolerance = tolerance;
    filler->traps = traps;

    filler->current_point.x = 0;
    filler->current_point.y = 0;

    _cairo_polygon_init (&filler->polygon);
}

static void
_cairo_filler_fini (cairo_filler_t *filler)
{
    _cairo_polygon_fini (&filler->polygon);
}

static cairo_status_t
_cairo_filler_move_to (void *closure, cairo_point_t *point)
{
    cairo_status_t status;
    cairo_filler_t *filler = closure;
    cairo_polygon_t *polygon = &filler->polygon;

    status = _cairo_polygon_close (polygon);
    if (status)
	return status;

    status = _cairo_polygon_move_to (polygon, point);
    if (status)
	return status;

    filler->current_point = *point;

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_filler_line_to (void *closure, cairo_point_t *point)
{
    cairo_status_t status;
    cairo_filler_t *filler = closure;
    cairo_polygon_t *polygon = &filler->polygon;

    status = _cairo_polygon_line_to (polygon, point);
    if (status)
	return status;

    filler->current_point = *point;

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_filler_curve_to (void *closure,
			cairo_point_t *b,
			cairo_point_t *c,
			cairo_point_t *d)
{
    int i;
    cairo_status_t status = CAIRO_STATUS_SUCCESS;
    cairo_filler_t *filler = closure;
    cairo_polygon_t *polygon = &filler->polygon;
    cairo_spline_t spline;

    status = _cairo_spline_init (&spline, &filler->current_point, b, c, d);

    if (status == CAIRO_INT_STATUS_DEGENERATE)
	return CAIRO_STATUS_SUCCESS;

    _cairo_spline_decompose (&spline, filler->tolerance);
    if (status)
	goto CLEANUP_SPLINE;

    for (i = 1; i < spline.num_points; i++) {
	status = _cairo_polygon_line_to (polygon, &spline.points[i]);
	if (status)
	    break;
    }

  CLEANUP_SPLINE:
    _cairo_spline_fini (&spline);

    filler->current_point = *d;

    return status;
}

static cairo_status_t
_cairo_filler_close_path (void *closure)
{
    cairo_status_t status;
    cairo_filler_t *filler = closure;
    cairo_polygon_t *polygon = &filler->polygon;

    status = _cairo_polygon_close (polygon);
    if (status)
	return status;

    return CAIRO_STATUS_SUCCESS;
}

cairo_status_t
_cairo_path_fixed_fill_to_traps (cairo_path_fixed_t *path,
				 cairo_fill_rule_t   fill_rule,
				 double              tolerance,
				 cairo_traps_t      *traps)
{
    cairo_status_t status = CAIRO_STATUS_SUCCESS;
    cairo_filler_t filler;

    _cairo_filler_init (&filler, tolerance, traps);

    status = _cairo_path_fixed_interpret (path,
					  CAIRO_DIRECTION_FORWARD,
					  _cairo_filler_move_to,
					  _cairo_filler_line_to,
					  _cairo_filler_curve_to,
					  _cairo_filler_close_path,
					  &filler);
    if (status)
	goto BAIL;

    status = _cairo_polygon_close (&filler.polygon);
    if (status)
	goto BAIL;

    status = _cairo_traps_tessellate_polygon (filler.traps,
					      &filler.polygon,
					      fill_rule);
    if (status)
	goto BAIL;

BAIL:
    _cairo_filler_fini (&filler);

    return status;
}