clip-twice.c

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

/*
 * Copyright © 2005 Red Hat, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose is hereby granted without
 * fee, provided that the above copyright notice appear in all copies
 * and that both that copyright notice and this permission notice
 * appear in supporting documentation, and that the name of
 * Red Hat, Inc. not be used in advertising or publicity pertaining to
 * distribution of the software without specific, written prior
 * permission. Red Hat, Inc. makes no representations about the
 * suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
 * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS, IN NO EVENT SHALL RED HAT, INC. BE LIABLE FOR ANY SPECIAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
 * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Author: Kristian Høgsberg <[e-mail]>
 */

#include "cairo-test.h"

#define WIDTH 64
#define HEIGHT 64

cairo_test_t test = {
    "clip-twice",
    "Verifies that the clip mask is updated correctly when it constructed by setting the clip path twice.",
    WIDTH, HEIGHT
};

static cairo_test_status_t
draw (cairo_t *cr, int width, int height)
{
    cairo_new_path (cr);
    cairo_arc (cr, WIDTH / 2, HEIGHT / 2, WIDTH / 3, 0, 2 * M_PI);
    cairo_clip (cr);

    cairo_new_path (cr);
    cairo_move_to (cr, 0, 0);
    cairo_line_to (cr, WIDTH / 4, HEIGHT / 2);
    cairo_line_to (cr, 0, HEIGHT);
    cairo_line_to (cr, WIDTH, HEIGHT);
    cairo_line_to (cr, 3 * WIDTH / 4, HEIGHT / 2);
    cairo_line_to (cr, WIDTH, 0);
    cairo_close_path (cr);
    cairo_clip (cr);

    cairo_set_source_rgb (cr, 0, 0, 0.6);

    cairo_new_path (cr);
    cairo_move_to (cr, 0, 0);
    cairo_line_to (cr, 0, HEIGHT);
    cairo_line_to (cr, WIDTH / 2, 3 * HEIGHT / 4);
    cairo_line_to (cr, WIDTH, HEIGHT);
    cairo_line_to (cr, WIDTH, 0);
    cairo_line_to (cr, WIDTH / 2, HEIGHT / 4);
    cairo_close_path (cr);
    cairo_fill (cr);

    cairo_new_path (cr);
    cairo_arc (cr, WIDTH / 2, HEIGHT / 2, WIDTH / 5, 0, 2 * M_PI);
    cairo_clip (cr);
    cairo_set_source_rgb (cr, 1, 1, 0);
    cairo_paint (cr);

    return CAIRO_TEST_SUCCESS;
}

int
main (void)
{
    return cairo_test (&test, draw);
}