cairo-region.c

/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2005 Red Hat, Inc.
 *
 * 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., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, 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):
 *	Owen Taylor <otaylor@redhat.com>
 *      Vladimir Vukicevic <vladimir@pobox.com>
 *      Søren Sandmann <sandmann@daimi.au.dk>
 */

#include "cairoint.h"

#include "cairo-error-private.h"
#include "cairo-region-private.h"

/* XXX need to update pixman headers to be const as appropriate */
#define CONST_CAST (pixman_region32_t *)

/**
 * SECTION:cairo-region
 * @Title: Regions
 * @Short_Description: Representing a pixel-aligned area
 *
 * Regions are a simple graphical data type representing an area of 
 * integer-aligned rectangles. They are often used on raster surfaces 
 * to track areas of interest, such as change or clip areas.
 **/

static const cairo_region_t _cairo_region_nil = {
    CAIRO_REFERENCE_COUNT_INVALID,	/* ref_count */
    CAIRO_STATUS_NO_MEMORY,		/* status */
};

cairo_region_t *
_cairo_region_create_in_error (cairo_status_t status)
{
    switch (status) {
    case CAIRO_STATUS_NO_MEMORY:
	return (cairo_region_t *) &_cairo_region_nil;

    case CAIRO_STATUS_SUCCESS:
    case CAIRO_STATUS_LAST_STATUS:
	ASSERT_NOT_REACHED;
	/* fall-through */
    case CAIRO_STATUS_SURFACE_TYPE_MISMATCH:
    case CAIRO_STATUS_INVALID_STATUS:
    case CAIRO_STATUS_INVALID_CONTENT:
    case CAIRO_STATUS_INVALID_FORMAT:
    case CAIRO_STATUS_INVALID_VISUAL:
    case CAIRO_STATUS_READ_ERROR:
    case CAIRO_STATUS_WRITE_ERROR:
    case CAIRO_STATUS_FILE_NOT_FOUND:
    case CAIRO_STATUS_TEMP_FILE_ERROR:
    case CAIRO_STATUS_INVALID_STRIDE:
    case CAIRO_STATUS_INVALID_SIZE:
    case CAIRO_STATUS_DEVICE_TYPE_MISMATCH:
    case CAIRO_STATUS_DEVICE_ERROR:
    case CAIRO_STATUS_INVALID_RESTORE:
    case CAIRO_STATUS_INVALID_POP_GROUP:
    case CAIRO_STATUS_NO_CURRENT_POINT:
    case CAIRO_STATUS_INVALID_MATRIX:
    case CAIRO_STATUS_NULL_POINTER:
    case CAIRO_STATUS_INVALID_STRING:
    case CAIRO_STATUS_INVALID_PATH_DATA:
    case CAIRO_STATUS_SURFACE_FINISHED:
    case CAIRO_STATUS_PATTERN_TYPE_MISMATCH:
    case CAIRO_STATUS_INVALID_DASH:
    case CAIRO_STATUS_INVALID_DSC_COMMENT:
    case CAIRO_STATUS_INVALID_INDEX:
    case CAIRO_STATUS_CLIP_NOT_REPRESENTABLE:
    case CAIRO_STATUS_FONT_TYPE_MISMATCH:
    case CAIRO_STATUS_USER_FONT_IMMUTABLE:
    case CAIRO_STATUS_USER_FONT_ERROR:
    case CAIRO_STATUS_NEGATIVE_COUNT:
    case CAIRO_STATUS_INVALID_CLUSTERS:
    case CAIRO_STATUS_INVALID_SLANT:
    case CAIRO_STATUS_INVALID_WEIGHT:
    case CAIRO_STATUS_USER_FONT_NOT_IMPLEMENTED:
    case CAIRO_STATUS_INVALID_MESH_CONSTRUCTION:
    case CAIRO_STATUS_DEVICE_FINISHED:
    case CAIRO_STATUS_JBIG2_GLOBAL_MISSING:
    case CAIRO_STATUS_PNG_ERROR:
    case CAIRO_STATUS_FREETYPE_ERROR:
    case CAIRO_STATUS_WIN32_GDI_ERROR:
    default:
	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
	return (cairo_region_t *) &_cairo_region_nil;
    }
}

/**
 * _cairo_region_set_error:
 * @region: a region
 * @status: a status value indicating an error
 *
 * Atomically sets region->status to @status and calls _cairo_error;
 * Does nothing if status is %CAIRO_STATUS_SUCCESS or any of the internal
 * status values.
 *
 * All assignments of an error status to region->status should happen
 * through _cairo_region_set_error(). Note that due to the nature of
 * the atomic operation, it is not safe to call this function on the
 * nil objects.
 *
 * The purpose of this function is to allow the user to set a
 * breakpoint in _cairo_error() to generate a stack trace for when the
 * user causes cairo to detect an error.
 *
 * Return value: the error status.
 **/
static cairo_status_t
_cairo_region_set_error (cairo_region_t *region,
			 cairo_status_t status)
{
    if (status == CAIRO_STATUS_SUCCESS)
        return CAIRO_STATUS_SUCCESS;

    /* Don't overwrite an existing error. This preserves the first
     * error, which is the most significant. */
    _cairo_status_set_error (&region->status, status);

    return _cairo_error (status);
}

void
_cairo_region_init (cairo_region_t *region)
{
    VG (VALGRIND_MAKE_MEM_UNDEFINED (region, sizeof (cairo_region_t)));

    region->status = CAIRO_STATUS_SUCCESS;
    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 0);
    pixman_region32_init (&region->rgn);
}

void
_cairo_region_init_rectangle (cairo_region_t *region,
			      const cairo_rectangle_int_t *rectangle)
{
    VG (VALGRIND_MAKE_MEM_UNDEFINED (region, sizeof (cairo_region_t)));

    region->status = CAIRO_STATUS_SUCCESS;
    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 0);
    pixman_region32_init_rect (&region->rgn,
			       rectangle->x, rectangle->y,
			       rectangle->width, rectangle->height);
}

void
_cairo_region_fini (cairo_region_t *region)
{
    assert (! CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&region->ref_count));
    pixman_region32_fini (&region->rgn);
    VG (VALGRIND_MAKE_MEM_UNDEFINED (region, sizeof (cairo_region_t)));
}

/**
 * cairo_region_create:
 *
 * Allocates a new empty region object.
 *
 * Return value: A newly allocated #cairo_region_t. Free with
 *   cairo_region_destroy(). This function always returns a
 *   valid pointer; if memory cannot be allocated, then a special
 *   error object is returned where all operations on the object do nothing.
 *   You can check for this with cairo_region_status().
 *
 * Since: 1.10
 **/
cairo_region_t *
cairo_region_create (void)
{
    cairo_region_t *region;

    region = _cairo_malloc (sizeof (cairo_region_t));
    if (region == NULL)
	return (cairo_region_t *) &_cairo_region_nil;

    region->status = CAIRO_STATUS_SUCCESS;
    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);

    pixman_region32_init (&region->rgn);

    return region;
}
slim_hidden_def (cairo_region_create);

/**
 * cairo_region_create_rectangles:
 * @rects: an array of @count rectangles
 * @count: number of rectangles
 *
 * Allocates a new region object containing the union of all given @rects.
 *
 * Return value: A newly allocated #cairo_region_t. Free with
 *   cairo_region_destroy(). This function always returns a
 *   valid pointer; if memory cannot be allocated, then a special
 *   error object is returned where all operations on the object do nothing.
 *   You can check for this with cairo_region_status().
 *
 * Since: 1.10
 **/
cairo_region_t *
cairo_region_create_rectangles (const cairo_rectangle_int_t *rects,
				int count)
{
    pixman_box32_t stack_pboxes[CAIRO_STACK_ARRAY_LENGTH (pixman_box32_t)];
    pixman_box32_t *pboxes = stack_pboxes;
    cairo_region_t *region;
    int i;

    region = _cairo_malloc (sizeof (cairo_region_t));
    if (unlikely (region == NULL))
	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));

    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);
    region->status = CAIRO_STATUS_SUCCESS;

    if (count == 1) {
	pixman_region32_init_rect (&region->rgn,
				   rects->x, rects->y,
				   rects->width, rects->height);

	return region;
    }

    if (count > ARRAY_LENGTH (stack_pboxes)) {
	pboxes = _cairo_malloc_ab (count, sizeof (pixman_box32_t));
	if (unlikely (pboxes == NULL)) {
	    free (region);
	    return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
	}
    }

    for (i = 0; i < count; i++) {
	pboxes[i].x1 = rects[i].x;
	pboxes[i].y1 = rects[i].y;
	pboxes[i].x2 = rects[i].x + rects[i].width;
	pboxes[i].y2 = rects[i].y + rects[i].height;
    }

    i = pixman_region32_init_rects (&region->rgn, pboxes, count);

    if (pboxes != stack_pboxes)
	free (pboxes);

    if (unlikely (i == 0)) {
	free (region);
	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
    }

    return region;
}
slim_hidden_def (cairo_region_create_rectangles);

cairo_region_t *
_cairo_region_create_from_boxes (const cairo_box_t *boxes, int count)
{
    cairo_region_t *region;

    region = _cairo_malloc (sizeof (cairo_region_t));
    if (unlikely (region == NULL))
	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));

    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);
    region->status = CAIRO_STATUS_SUCCESS;

    if (! pixman_region32_init_rects (&region->rgn,
				      (pixman_box32_t *)boxes, count)) {
	free (region);
	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
    }

    return region;
}

cairo_box_t *
_cairo_region_get_boxes (const cairo_region_t *region, int *nbox)
{
    if (region->status) {
	nbox = 0;
	return NULL;
    }

    return (cairo_box_t *) pixman_region32_rectangles (CONST_CAST &region->rgn, nbox);
}

/**
 * cairo_region_create_rectangle:
 * @rectangle: a #cairo_rectangle_int_t
 *
 * Allocates a new region object containing @rectangle.
 *
 * Return value: A newly allocated #cairo_region_t. Free with
 *   cairo_region_destroy(). This function always returns a
 *   valid pointer; if memory cannot be allocated, then a special
 *   error object is returned where all operations on the object do nothing.
 *   You can check for this with cairo_region_status().
 *
 * Since: 1.10
 **/
cairo_region_t *
cairo_region_create_rectangle (const cairo_rectangle_int_t *rectangle)
{
    cairo_region_t *region;

    region = _cairo_malloc (sizeof (cairo_region_t));
    if (unlikely (region == NULL))
	return (cairo_region_t *) &_cairo_region_nil;

    region->status = CAIRO_STATUS_SUCCESS;
    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);

    pixman_region32_init_rect (&region->rgn,
			       rectangle->x, rectangle->y,
			       rectangle->width, rectangle->height);

    return region;
}
slim_hidden_def (cairo_region_create_rectangle);

/**
 * cairo_region_copy:
 * @original: a #cairo_region_t
 *
 * Allocates a new region object copying the area from @original.
 *
 * Return value: A newly allocated #cairo_region_t. Free with
 *   cairo_region_destroy(). This function always returns a
 *   valid pointer; if memory cannot be allocated, then a special
 *   error object is returned where all operations on the object do nothing.
 *   You can check for this with cairo_region_status().
 *
 * Since: 1.10
 **/
cairo_region_t *
cairo_region_copy (const cairo_region_t *original)
{
    cairo_region_t *copy;

    if (original != NULL && original->status)
	return (cairo_region_t *) &_cairo_region_nil;

    copy = cairo_region_create ();
    if (unlikely (copy->status))
	return copy;

    if (original != NULL &&
	! pixman_region32_copy (&copy->rgn, CONST_CAST &original->rgn))
    {
	cairo_region_destroy (copy);
	return (cairo_region_t *) &_cairo_region_nil;
    }

    return copy;
}
slim_hidden_def (cairo_region_copy);

/**
 * cairo_region_reference:
 * @region: a #cairo_region_t
 *
 * Increases the reference count on @region by one. This prevents
 * @region from being destroyed until a matching call to
 * cairo_region_destroy() is made.
 *
 * Return value: the referenced #cairo_region_t.
 *
 * Since: 1.10
 **/
cairo_region_t *
cairo_region_reference (cairo_region_t *region)
{
    if (region == NULL || CAIRO_REFERENCE_COUNT_IS_INVALID (&region->ref_count))
	return NULL;

    assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&region->ref_count));

    _cairo_reference_count_inc (&region->ref_count);
    return region;
}
slim_hidden_def (cairo_region_reference);

/**
 * cairo_region_destroy:
 * @region: a #cairo_region_t
 *
 * Destroys a #cairo_region_t object created with
 * cairo_region_create(), cairo_region_copy(), or
 * or cairo_region_create_rectangle().
 *
 * Since: 1.10
 **/
void
cairo_region_destroy (cairo_region_t *region)
{
    if (region == NULL || CAIRO_REFERENCE_COUNT_IS_INVALID (&region->ref_count))
	return;

    assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&region->ref_count));

    if (! _cairo_reference_count_dec_and_test (&region->ref_count))
	return;

    _cairo_region_fini (region);
    free (region);
}
slim_hidden_def (cairo_region_destroy);

/**
 * cairo_region_num_rectangles:
 * @region: a #cairo_region_t
 *
 * Returns the number of rectangles contained in @region.
 *
 * Return value: The number of rectangles contained in @region.
 *
 * Since: 1.10
 **/
int
cairo_region_num_rectangles (const cairo_region_t *region)
{
    if (region->status)
	return 0;

    return pixman_region32_n_rects (CONST_CAST &region->rgn);
}
slim_hidden_def (cairo_region_num_rectangles);

/**
 * cairo_region_get_rectangle:
 * @region: a #cairo_region_t
 * @nth: a number indicating which rectangle should be returned
 * @rectangle: return location for a #cairo_rectangle_int_t
 *
 * Stores the @nth rectangle from the region in @rectangle.
 *
 * Since: 1.10
 **/
void
cairo_region_get_rectangle (const cairo_region_t *region,
			    int nth,
			    cairo_rectangle_int_t *rectangle)
{
    pixman_box32_t *pbox;

    if (region->status) {
	rectangle->x = rectangle->y = 0;
	rectangle->width = rectangle->height = 0;
	return;
    }

    pbox = pixman_region32_rectangles (CONST_CAST &region->rgn, NULL) + nth;

    rectangle->x = pbox->x1;
    rectangle->y = pbox->y1;
    rectangle->width = pbox->x2 - pbox->x1;
    rectangle->height = pbox->y2 - pbox->y1;
}
slim_hidden_def (cairo_region_get_rectangle);

/**
 * cairo_region_get_extents:
 * @region: a #cairo_region_t
 * @extents: rectangle into which to store the extents
 *
 * Gets the bounding rectangle of @region as a #cairo_rectangle_int_t
 *
 * Since: 1.10
 **/
void
cairo_region_get_extents (const cairo_region_t *region,
			  cairo_rectangle_int_t *extents)
{
    pixman_box32_t *pextents;

    if (region->status) {
	extents->x = extents->y = 0;
	extents->width = extents->height = 0;
	return;
    }

    pextents = pixman_region32_extents (CONST_CAST &region->rgn);

    extents->x = pextents->x1;
    extents->y = pextents->y1;
    extents->width = pextents->x2 - pextents->x1;
    extents->height = pextents->y2 - pextents->y1;
}
slim_hidden_def (cairo_region_get_extents);

/**
 * cairo_region_status:
 * @region: a #cairo_region_t
 *
 * Checks whether an error has previous occurred for this
 * region object.
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_status (const cairo_region_t *region)
{
    return region->status;
}
slim_hidden_def (cairo_region_status);

/**
 * cairo_region_subtract:
 * @dst: a #cairo_region_t
 * @other: another #cairo_region_t
 *
 * Subtracts @other from @dst and places the result in @dst
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_subtract (cairo_region_t *dst, const cairo_region_t *other)
{
    if (dst->status)
	return dst->status;

    if (other->status)
	return _cairo_region_set_error (dst, other->status);

    if (! pixman_region32_subtract (&dst->rgn,
				    &dst->rgn,
				    CONST_CAST &other->rgn))
    {
	return _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);
    }

    return CAIRO_STATUS_SUCCESS;
}
slim_hidden_def (cairo_region_subtract);

/**
 * cairo_region_subtract_rectangle:
 * @dst: a #cairo_region_t
 * @rectangle: a #cairo_rectangle_int_t
 *
 * Subtracts @rectangle from @dst and places the result in @dst
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_subtract_rectangle (cairo_region_t *dst,
				 const cairo_rectangle_int_t *rectangle)
{
    cairo_status_t status = CAIRO_STATUS_SUCCESS;
    pixman_region32_t region;

    if (dst->status)
	return dst->status;

    pixman_region32_init_rect (&region,
			       rectangle->x, rectangle->y,
			       rectangle->width, rectangle->height);

    if (! pixman_region32_subtract (&dst->rgn, &dst->rgn, &region))
	status = _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);

    pixman_region32_fini (&region);

    return status;
}
slim_hidden_def (cairo_region_subtract_rectangle);

/**
 * cairo_region_intersect:
 * @dst: a #cairo_region_t
 * @other: another #cairo_region_t
 *
 * Computes the intersection of @dst with @other and places the result in @dst
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_intersect (cairo_region_t *dst, const cairo_region_t *other)
{
    if (dst->status)
	return dst->status;

    if (other->status)
	return _cairo_region_set_error (dst, other->status);

    if (! pixman_region32_intersect (&dst->rgn, &dst->rgn, CONST_CAST &other->rgn))
	return _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);

    return CAIRO_STATUS_SUCCESS;
}
slim_hidden_def (cairo_region_intersect);

/**
 * cairo_region_intersect_rectangle:
 * @dst: a #cairo_region_t
 * @rectangle: a #cairo_rectangle_int_t
 *
 * Computes the intersection of @dst with @rectangle and places the
 * result in @dst
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_intersect_rectangle (cairo_region_t *dst,
				  const cairo_rectangle_int_t *rectangle)
{
    cairo_status_t status = CAIRO_STATUS_SUCCESS;
    pixman_region32_t region;

    if (dst->status)
	return dst->status;

    pixman_region32_init_rect (&region,
			       rectangle->x, rectangle->y,
			       rectangle->width, rectangle->height);

    if (! pixman_region32_intersect (&dst->rgn, &dst->rgn, &region))
	status = _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);

    pixman_region32_fini (&region);

    return status;
}
slim_hidden_def (cairo_region_intersect_rectangle);

/**
 * cairo_region_union:
 * @dst: a #cairo_region_t
 * @other: another #cairo_region_t
 *
 * Computes the union of @dst with @other and places the result in @dst
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_union (cairo_region_t *dst,
		    const cairo_region_t *other)
{
    if (dst->status)
	return dst->status;

    if (other->status)
	return _cairo_region_set_error (dst, other->status);

    if (! pixman_region32_union (&dst->rgn, &dst->rgn, CONST_CAST &other->rgn))
	return _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);

    return CAIRO_STATUS_SUCCESS;
}
slim_hidden_def (cairo_region_union);

/**
 * cairo_region_union_rectangle:
 * @dst: a #cairo_region_t
 * @rectangle: a #cairo_rectangle_int_t
 *
 * Computes the union of @dst with @rectangle and places the result in @dst.
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_union_rectangle (cairo_region_t *dst,
			      const cairo_rectangle_int_t *rectangle)
{
    cairo_status_t status = CAIRO_STATUS_SUCCESS;
    pixman_region32_t region;

    if (dst->status)
	return dst->status;

    pixman_region32_init_rect (&region,
			       rectangle->x, rectangle->y,
			       rectangle->width, rectangle->height);

    if (! pixman_region32_union (&dst->rgn, &dst->rgn, &region))
	status = _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);

    pixman_region32_fini (&region);

    return status;
}
slim_hidden_def (cairo_region_union_rectangle);

/**
 * cairo_region_xor:
 * @dst: a #cairo_region_t
 * @other: another #cairo_region_t
 *
 * Computes the exclusive difference of @dst with @other and places the
 * result in @dst. That is, @dst will be set to contain all areas that
 * are either in @dst or in @other, but not in both.
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_xor (cairo_region_t *dst, const cairo_region_t *other)
{
    cairo_status_t status = CAIRO_STATUS_SUCCESS;
    pixman_region32_t tmp;

    if (dst->status)
	return dst->status;

    if (other->status)
	return _cairo_region_set_error (dst, other->status);

    pixman_region32_init (&tmp);

    /* XXX: get an xor function into pixman */
    if (! pixman_region32_subtract (&tmp, CONST_CAST &other->rgn, &dst->rgn) ||
        ! pixman_region32_subtract (&dst->rgn, &dst->rgn, CONST_CAST &other->rgn) || 
        ! pixman_region32_union (&dst->rgn, &dst->rgn, &tmp))
	status = _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);

    pixman_region32_fini (&tmp);

    return status;
}
slim_hidden_def (cairo_region_xor);

/**
 * cairo_region_xor_rectangle:
 * @dst: a #cairo_region_t
 * @rectangle: a #cairo_rectangle_int_t
 *
 * Computes the exclusive difference of @dst with @rectangle and places the
 * result in @dst. That is, @dst will be set to contain all areas that are 
 * either in @dst or in @rectangle, but not in both.
 *
 * Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY
 *
 * Since: 1.10
 **/
cairo_status_t
cairo_region_xor_rectangle (cairo_region_t *dst,
			    const cairo_rectangle_int_t *rectangle)
{
    cairo_status_t status = CAIRO_STATUS_SUCCESS;
    pixman_region32_t region, tmp;

    if (dst->status)
	return dst->status;

    pixman_region32_init_rect (&region,
			       rectangle->x, rectangle->y,
			       rectangle->width, rectangle->height);
    pixman_region32_init (&tmp);

    /* XXX: get an xor function into pixman */
    if (! pixman_region32_subtract (&tmp, &region, &dst->rgn) ||
        ! pixman_region32_subtract (&dst->rgn, &dst->rgn, &region) || 
        ! pixman_region32_union (&dst->rgn, &dst->rgn, &tmp))
	status = _cairo_region_set_error (dst, CAIRO_STATUS_NO_MEMORY);

    pixman_region32_fini (&tmp);
    pixman_region32_fini (&region);

    return status;
}
slim_hidden_def (cairo_region_xor_rectangle);

/**
 * cairo_region_is_empty:
 * @region: a #cairo_region_t
 *
 * Checks whether @region is empty.
 *
 * Return value: %TRUE if @region is empty, %FALSE if it isn't.
 *
 * Since: 1.10
 **/
cairo_bool_t
cairo_region_is_empty (const cairo_region_t *region)
{
    if (region->status)
	return TRUE;

    return ! pixman_region32_not_empty (CONST_CAST &region->rgn);
}
slim_hidden_def (cairo_region_is_empty);

/**
 * cairo_region_translate:
 * @region: a #cairo_region_t
 * @dx: Amount to translate in the x direction
 * @dy: Amount to translate in the y direction
 *
 * Translates @region by (@dx, @dy).
 *
 * Since: 1.10
 **/
void
cairo_region_translate (cairo_region_t *region,
			int dx, int dy)
{
    if (region->status)
	return;

    pixman_region32_translate (&region->rgn, dx, dy);
}
slim_hidden_def (cairo_region_translate);

/**
 * cairo_region_contains_rectangle:
 * @region: a #cairo_region_t
 * @rectangle: a #cairo_rectangle_int_t
 *
 * Checks whether @rectangle is inside, outside or partially contained
 * in @region
 *
 * Return value:
 *   %CAIRO_REGION_OVERLAP_IN if @rectangle is entirely inside @region,
 *   %CAIRO_REGION_OVERLAP_OUT if @rectangle is entirely outside @region, or
 *   %CAIRO_REGION_OVERLAP_PART if @rectangle is partially inside and partially outside @region.
 *
 * Since: 1.10
 **/
cairo_region_overlap_t
cairo_region_contains_rectangle (const cairo_region_t *region,
				 const cairo_rectangle_int_t *rectangle)
{
    pixman_box32_t pbox;
    pixman_region_overlap_t poverlap;

    if (region->status)
	return CAIRO_REGION_OVERLAP_OUT;

    pbox.x1 = rectangle->x;
    pbox.y1 = rectangle->y;
    pbox.x2 = rectangle->x + rectangle->width;
    pbox.y2 = rectangle->y + rectangle->height;

    poverlap = pixman_region32_contains_rectangle (CONST_CAST &region->rgn,
						   &pbox);
    switch (poverlap) {
    default:
    case PIXMAN_REGION_OUT:  return CAIRO_REGION_OVERLAP_OUT;
    case PIXMAN_REGION_IN:   return CAIRO_REGION_OVERLAP_IN;
    case PIXMAN_REGION_PART: return CAIRO_REGION_OVERLAP_PART;
    }
}
slim_hidden_def (cairo_region_contains_rectangle);

/**
 * cairo_region_contains_point:
 * @region: a #cairo_region_t
 * @x: the x coordinate of a point
 * @y: the y coordinate of a point
 *
 * Checks whether (@x, @y) is contained in @region.
 *
 * Return value: %TRUE if (@x, @y) is contained in @region, %FALSE if it is not.
 *
 * Since: 1.10
 **/
cairo_bool_t
cairo_region_contains_point (const cairo_region_t *region,
			     int x, int y)
{
    pixman_box32_t box;

    if (region->status)
	return FALSE;

    return pixman_region32_contains_point (CONST_CAST &region->rgn, x, y, &box);
}
slim_hidden_def (cairo_region_contains_point);

/**
 * cairo_region_equal:
 * @a: a #cairo_region_t or %NULL
 * @b: a #cairo_region_t or %NULL
 *
 * Compares whether region_a is equivalent to region_b. %NULL as an argument
 * is equal to itself, but not to any non-%NULL region.
 *
 * Return value: %TRUE if both regions contained the same coverage,
 * %FALSE if it is not or any region is in an error status.
 *
 * Since: 1.10
 **/
cairo_bool_t
cairo_region_equal (const cairo_region_t *a,
		    const cairo_region_t *b)
{
    /* error objects are never equal */
    if ((a != NULL && a->status) || (b != NULL && b->status))
	return FALSE;

    if (a == b)
	return TRUE;

    if (a == NULL || b == NULL)
	return FALSE;

    return pixman_region32_equal (CONST_CAST &a->rgn, CONST_CAST &b->rgn);
}
slim_hidden_def (cairo_region_equal);