Quelle  cairo-path-bounds.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 © 2003 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., 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 University of Southern
 * California.
 *
 * Contributor(s):
 * Carl D. Worth <cworth@cworth.org>
 */

#include "cairoint.h"
#include "cairo-box-inline.h"
#include "cairo-error-private.h"
#include "cairo-path-fixed-private.h"

typedef struct _cairo_path_bounder {
    cairo_point_t current_point;
    cairo_bool_t has_extents;
    cairo_box_t extents;
} cairo_path_bounder_t;

static cairo_status_t
_cairo_path_bounder_move_to (void *closure,
        const cairo_point_t *point)
{
    cairo_path_bounder_t *bounder = closure;

    bounder->current_point = *point;

    if (likely (bounder->has_extents)) {
 _cairo_box_add_point (&bounder->extents, point);
    } else {
 bounder->has_extents = TRUE;
 _cairo_box_set (&bounder->extents, point, point);
    }

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_path_bounder_line_to (void *closure,
        const cairo_point_t *point)
{
    cairo_path_bounder_t *bounder = closure;

    bounder->current_point = *point;
    _cairo_box_add_point (&bounder->extents, point);

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_path_bounder_curve_to (void *closure,
         const cairo_point_t *b,
         const cairo_point_t *c,
         const cairo_point_t *d)
{
    cairo_path_bounder_t *bounder = closure;

    _cairo_box_add_curve_to (&bounder->extents,
        &bounder->current_point,
        b, c, d);
    bounder->current_point = *d;

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_path_bounder_close_path (void *closure)
{
    return CAIRO_STATUS_SUCCESS;
}

cairo_bool_t
_cairo_path_bounder_extents (const cairo_path_fixed_t *path,
        cairo_box_t *extents)
{
    cairo_path_bounder_t bounder;
    cairo_status_t status;

    bounder.has_extents = FALSE;
    status = _cairo_path_fixed_interpret (path,
       _cairo_path_bounder_move_to,
       _cairo_path_bounder_line_to,
       _cairo_path_bounder_curve_to,
       _cairo_path_bounder_close_path,
       &bounder);
    assert (!status);

    if (bounder.has_extents)
 *extents = bounder.extents;

    return bounder.has_extents;
}

void
_cairo_path_fixed_approximate_clip_extents (const cairo_path_fixed_t *path,
         cairo_rectangle_int_t *extents)
{
    _cairo_path_fixed_approximate_fill_extents (path, extents);
}

void
_cairo_path_fixed_approximate_fill_extents (const cairo_path_fixed_t *path,
         cairo_rectangle_int_t *extents)
{
    _cairo_path_fixed_fill_extents (path, CAIRO_FILL_RULE_WINDING, 0, extents);
}

void
_cairo_path_fixed_fill_extents (const cairo_path_fixed_t *path,
    cairo_fill_rule_t  fill_rule,
    double    tolerance,
    cairo_rectangle_int_t *extents)
{
    if (path->extents.p1.x < path->extents.p2.x &&
 path->extents.p1.y < path->extents.p2.y) {
 _cairo_box_round_to_rectangle (&path->extents, extents);
    } else {
 extents->x = extents->y = 0;
 extents->width = extents->height = 0;
    }
}

/* Adjusts the fill extents (above) by the device-space pen.  */
void
_cairo_path_fixed_approximate_stroke_extents (const cairo_path_fixed_t *path,
           const cairo_stroke_style_t *style,
           const cairo_matrix_t *ctm,
           cairo_bool_t is_vector,
           cairo_rectangle_int_t *extents)
{
    if (path->has_extents) {
 cairo_box_t box_extents;
 double dx, dy;

 _cairo_stroke_style_max_distance_from_path (style, path, ctm, &dx, &dy);
 if (is_vector)
 {
     /* When calculating extents for vector surfaces, ensure lines thinner
     * than the fixed point resolution are not optimized away. */
     double min = _cairo_fixed_to_double (CAIRO_FIXED_EPSILON*2);
     if (dx < min)
  dx = min;

     if (dy < min)
  dy = min;
 }

 box_extents = path->extents;
 box_extents.p1.x -= _cairo_fixed_from_double (dx);
 box_extents.p1.y -= _cairo_fixed_from_double (dy);
 box_extents.p2.x += _cairo_fixed_from_double (dx);
 box_extents.p2.y += _cairo_fixed_from_double (dy);

 _cairo_box_round_to_rectangle (&box_extents, extents);
    } else {
 extents->x = extents->y = 0;
 extents->width = extents->height = 0;
    }
}

cairo_status_t
_cairo_path_fixed_stroke_extents (const cairo_path_fixed_t *path,
      const cairo_stroke_style_t *stroke_style,
      const cairo_matrix_t  *ctm,
      const cairo_matrix_t  *ctm_inverse,
      double    tolerance,
      cairo_rectangle_int_t  *extents)
{
    cairo_polygon_t polygon;
    cairo_status_t status;
    cairo_stroke_style_t style;

    /* When calculating extents for vector surfaces, ensure lines thinner
     * than one point are not optimized away. */
    double min_line_width = _cairo_matrix_transformed_circle_major_axis (ctm_inverse, 1.0);
    if (stroke_style->line_width < min_line_width)
    {
 style = *stroke_style;
 style.line_width = min_line_width;
 stroke_style = &style;
    }

    _cairo_polygon_init (&polygon, NULL, 0);
    status = _cairo_path_fixed_stroke_to_polygon (path,
        stroke_style,
        ctm, ctm_inverse,
        tolerance,
        &polygon);
    _cairo_box_round_to_rectangle (&polygon.extents, extents);
    _cairo_polygon_fini (&polygon);

    return status;
}

cairo_bool_t
_cairo_path_fixed_extents (const cairo_path_fixed_t *path,
      cairo_box_t *box)
{
    *box = path->extents;
    return path->has_extents;
}