cairo/src/cairo-surface-clipper.c

/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2009 Chris Wilson
 *
 * 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 Red Hat, Inc.
 *
 * Contributor(s):
 *      Chris Wilson <chris@chris-wilson.co.uk>
 */

#include "cairoint.h"

#include "cairo-surface-clipper-private.h"

/* A collection of routines to facilitate vector surface clipping */

static cairo_status_t
_cairo_surface_clipper_intersect_clip_path_recursive (cairo_surface_clipper_t *clipper,
						      cairo_clip_path_t *clip_path)
{
    cairo_status_t status;

    if (clip_path->prev != NULL) {
	status =
	    _cairo_surface_clipper_intersect_clip_path_recursive (clipper,
								  clip_path->prev);
	if (unlikely (status))
	    return status;
    }

    return clipper->intersect_clip_path (clipper,
					 &clip_path->path,
					 clip_path->fill_rule,
					 clip_path->tolerance,
					 clip_path->antialias);
}

cairo_status_t
_cairo_surface_clipper_set_clip (cairo_surface_clipper_t *clipper,
				 cairo_clip_t *clip)
{
    cairo_status_t status;
    cairo_bool_t clear;

    /* XXX as we cache a reference to the path, and compare every time,
     * we may in future need to install a notification if the clip->path
     * is every modified (e.g. cairo_clip_translate).
     */

    if (clip == NULL && clipper->clip.path == NULL)
	return CAIRO_STATUS_SUCCESS;

    if (clip != NULL && clip->path == clipper->clip.path)
	return CAIRO_STATUS_SUCCESS;

    if (clip != NULL && clipper->clip.path != NULL &&
	_cairo_path_fixed_equal (&clip->path->path, &clipper->clip.path->path))
    {
	return CAIRO_STATUS_SUCCESS;
    }

    /* all clipped out state should never propagate this far */
    assert (clip == NULL || clip->path != NULL);

    /* Check whether this clip is a continuation of the previous.
     * If not, we have to remove the current clip and rebuild.
     */
    clear = clip == NULL || clip->path->prev != clipper->clip.path;

    _cairo_clip_reset (&clipper->clip);
    _cairo_clip_init_copy (&clipper->clip, clip);

    if (clear) {
	clipper->is_clipped = FALSE;
	status = clipper->intersect_clip_path (clipper, NULL, 0, 0, 0);
	if (unlikely (status))
	    return status;

	if (clip != NULL && clip->path != NULL) {
	    status =
		_cairo_surface_clipper_intersect_clip_path_recursive (clipper,
								      clip->path);
	    clipper->is_clipped = TRUE;
	}
    } else {
	cairo_clip_path_t *path = clip->path;

	clipper->is_clipped = TRUE;
	status = clipper->intersect_clip_path (clipper,
					       &path->path,
					       path->fill_rule,
					       path->tolerance,
					       path->antialias);
    }

    return status;
}

void
_cairo_surface_clipper_init (cairo_surface_clipper_t *clipper,
			     cairo_surface_clipper_intersect_clip_path_func_t func)
{
    _cairo_clip_init (&clipper->clip);
    clipper->is_clipped = FALSE;
    clipper->intersect_clip_path = func;
}

void
_cairo_surface_clipper_reset (cairo_surface_clipper_t *clipper)
{
    _cairo_clip_reset (&clipper->clip);
    clipper->is_clipped = FALSE;
}