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813cbf13dd
Based on feedback from Jeff Muizelaar, there is a case for a very quick and dirty extents approximation based solely on the curve control points (for example when computing the clip intersect rectangle of a path) and by moving the stroke extension into a core function we can clean up the interface for all users, and centralise the logic of approximating the stroke extents.
304 lines
8.5 KiB
C
304 lines
8.5 KiB
C
/* cairo - a vector graphics library with display and print output
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*
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* Copyright © 2003 University of Southern California
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*
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* This library is free software; you can redistribute it and/or
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* modify it either under the terms of the GNU Lesser General Public
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* License version 2.1 as published by the Free Software Foundation
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* (the "LGPL") or, at your option, under the terms of the Mozilla
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* Public License Version 1.1 (the "MPL"). If you do not alter this
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* notice, a recipient may use your version of this file under either
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* the MPL or the LGPL.
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*
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* You should have received a copy of the LGPL along with this library
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* in the file COPYING-LGPL-2.1; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* You should have received a copy of the MPL along with this library
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* in the file COPYING-MPL-1.1
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
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* OF ANY KIND, either express or implied. See the LGPL or the MPL for
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* the specific language governing rights and limitations.
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*
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* The Original Code is the cairo graphics library.
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*
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* The Initial Developer of the Original Code is University of Southern
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* California.
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*
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* Contributor(s):
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* Carl D. Worth <cworth@cworth.org>
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*/
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#include "cairoint.h"
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typedef struct cairo_path_bounder {
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double tolerance;
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cairo_point_t move_to_point;
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cairo_bool_t has_move_to_point;
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cairo_bool_t has_point;
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cairo_box_t extents;
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} cairo_path_bounder_t;
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static void
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_cairo_path_bounder_init (cairo_path_bounder_t *bounder, double tolerance)
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{
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bounder->tolerance = tolerance;
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bounder->has_move_to_point = FALSE;
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bounder->has_point = FALSE;
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}
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static void
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_cairo_path_bounder_fini (cairo_path_bounder_t *bounder)
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{
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bounder->has_move_to_point = FALSE;
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bounder->has_point = FALSE;
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}
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static void
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_cairo_path_bounder_add_point (cairo_path_bounder_t *bounder,
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const cairo_point_t *point)
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{
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if (bounder->has_point) {
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if (point->x < bounder->extents.p1.x)
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bounder->extents.p1.x = point->x;
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if (point->y < bounder->extents.p1.y)
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bounder->extents.p1.y = point->y;
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if (point->x > bounder->extents.p2.x)
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bounder->extents.p2.x = point->x;
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if (point->y > bounder->extents.p2.y)
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bounder->extents.p2.y = point->y;
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} else {
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bounder->extents.p1.x = point->x;
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bounder->extents.p1.y = point->y;
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bounder->extents.p2.x = point->x;
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bounder->extents.p2.y = point->y;
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bounder->has_point = TRUE;
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}
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}
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static cairo_status_t
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_cairo_path_bounder_move_to (void *closure,
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const cairo_point_t *point)
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{
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cairo_path_bounder_t *bounder = closure;
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bounder->move_to_point = *point;
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bounder->has_move_to_point = TRUE;
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return CAIRO_STATUS_SUCCESS;
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}
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static cairo_status_t
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_cairo_path_bounder_line_to (void *closure,
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const cairo_point_t *point)
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{
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cairo_path_bounder_t *bounder = closure;
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if (bounder->has_move_to_point) {
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_cairo_path_bounder_add_point (bounder,
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&bounder->move_to_point);
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bounder->has_move_to_point = FALSE;
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}
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_cairo_path_bounder_add_point (bounder, point);
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return CAIRO_STATUS_SUCCESS;
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}
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static cairo_status_t
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_cairo_path_bounder_curve_to (void *closure,
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const cairo_point_t *b,
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const cairo_point_t *c,
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const cairo_point_t *d)
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{
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cairo_path_bounder_t *bounder = closure;
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cairo_spline_t spline;
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/* XXX Is there a faster way to determine the bounding box of a
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* Bezier curve than its decomposition?
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*
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* Using the control points alone can be wildly inaccurate.
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*/
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if (! _cairo_spline_init (&spline,
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_cairo_path_bounder_line_to, bounder,
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&bounder->move_to_point, b, c, d))
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{
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return _cairo_path_bounder_line_to (bounder, d);
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}
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return _cairo_spline_decompose (&spline, bounder->tolerance);
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}
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static cairo_status_t
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_cairo_path_bounder_curve_to_cp (void *closure,
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const cairo_point_t *b,
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const cairo_point_t *c,
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const cairo_point_t *d)
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{
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cairo_path_bounder_t *bounder = closure;
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if (bounder->has_move_to_point) {
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_cairo_path_bounder_add_point (bounder,
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&bounder->move_to_point);
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bounder->has_move_to_point = FALSE;
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}
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_cairo_path_bounder_add_point (bounder, b);
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_cairo_path_bounder_add_point (bounder, c);
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_cairo_path_bounder_add_point (bounder, d);
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return CAIRO_STATUS_SUCCESS;
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}
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static cairo_status_t
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_cairo_path_bounder_close_path (void *closure)
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{
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return CAIRO_STATUS_SUCCESS;
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}
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/* This computes the extents of all the points in the path, not those of
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* the damage area (i.e it does not consider winding and it only inspects
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* the control points of the curves, not the flattened path).
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*/
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void
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_cairo_path_fixed_approximate_extents (cairo_path_fixed_t *path,
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cairo_rectangle_int_t *extents)
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{
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cairo_path_bounder_t bounder;
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cairo_status_t status;
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_cairo_path_bounder_init (&bounder, 0.);
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status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
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_cairo_path_bounder_move_to,
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_cairo_path_bounder_line_to,
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_cairo_path_bounder_curve_to_cp,
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_cairo_path_bounder_close_path,
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&bounder);
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assert (status == CAIRO_STATUS_SUCCESS);
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if (bounder.has_point) {
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_cairo_box_round_to_rectangle (&bounder.extents, extents);
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} else {
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extents->x = extents->y = 0;
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extents->width = extents->width = 0;
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}
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_cairo_path_bounder_fini (&bounder);
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}
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/* A slightly better approximation than above - we actually decompose the
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* Bezier, but we continue to ignore winding.
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*/
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void
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_cairo_path_fixed_approximate_fill_extents (cairo_path_fixed_t *path,
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double tolerance,
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cairo_rectangle_int_t *extents)
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{
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cairo_path_bounder_t bounder;
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cairo_status_t status;
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_cairo_path_bounder_init (&bounder, tolerance);
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status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
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_cairo_path_bounder_move_to,
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_cairo_path_bounder_line_to,
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_cairo_path_bounder_curve_to,
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_cairo_path_bounder_close_path,
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&bounder);
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assert (status == CAIRO_STATUS_SUCCESS);
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if (bounder.has_point) {
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_cairo_box_round_to_rectangle (&bounder.extents, extents);
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} else {
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extents->x = extents->y = 0;
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extents->width = extents->width = 0;
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}
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_cairo_path_bounder_fini (&bounder);
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}
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/* Adjusts the fill extents (above) by the device-space pen. */
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void
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_cairo_path_fixed_approximate_stroke_extents (cairo_path_fixed_t *path,
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cairo_stroke_style_t *style,
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const cairo_matrix_t *ctm,
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double tolerance,
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cairo_rectangle_int_t *extents)
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{
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cairo_path_bounder_t bounder;
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cairo_status_t status;
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_cairo_path_bounder_init (&bounder, tolerance);
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status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
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_cairo_path_bounder_move_to,
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_cairo_path_bounder_line_to,
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_cairo_path_bounder_curve_to,
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_cairo_path_bounder_close_path,
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&bounder);
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assert (status == CAIRO_STATUS_SUCCESS);
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if (bounder.has_point) {
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double dx, dy;
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_cairo_stroke_style_max_distance_from_path (style, ctm, &dx, &dy);
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bounder.extents.p1.x -= _cairo_fixed_from_double (dx);
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bounder.extents.p2.x += _cairo_fixed_from_double (dx);
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bounder.extents.p1.y -= _cairo_fixed_from_double (dy);
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bounder.extents.p2.y += _cairo_fixed_from_double (dy);
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_cairo_box_round_to_rectangle (&bounder.extents, extents);
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} else {
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extents->x = extents->y = 0;
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extents->width = extents->width = 0;
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}
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_cairo_path_bounder_fini (&bounder);
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}
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void
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_cairo_path_fixed_bounds (cairo_path_fixed_t *path,
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double *x1, double *y1,
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double *x2, double *y2,
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double tolerance)
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{
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cairo_path_bounder_t bounder;
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cairo_status_t status;
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_cairo_path_bounder_init (&bounder, tolerance);
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status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
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_cairo_path_bounder_move_to,
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_cairo_path_bounder_line_to,
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_cairo_path_bounder_curve_to,
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_cairo_path_bounder_close_path,
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&bounder);
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assert (status == CAIRO_STATUS_SUCCESS);
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if (bounder.has_point) {
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*x1 = _cairo_fixed_to_double (bounder.extents.p1.x);
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*y1 = _cairo_fixed_to_double (bounder.extents.p1.y);
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*x2 = _cairo_fixed_to_double (bounder.extents.p2.x);
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*y2 = _cairo_fixed_to_double (bounder.extents.p2.y);
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} else {
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*x1 = 0.0;
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*y1 = 0.0;
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*x2 = 0.0;
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*y2 = 0.0;
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}
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_cairo_path_bounder_fini (&bounder);
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}
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