paint-source-alpha.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.
 * Copyright © 2006 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: Carl D. Worth <[e-mail]>
 */

#include "cairo-test.h"

cairo_test_t test = {
    "paint-source-alpha",
    "Simple test of cairo_paint with a source surface with non-opaque alpha",
    32, 32
};

static cairo_test_status_t
draw (cairo_t *cr, int width, int height)
{
    cairo_surface_t *surface;
    static uint32_t data[16] = {
	0x80808080, 0x80808080,		0x80800000, 0x80800000,
	0x80808080, 0x80808080,		0x80800000, 0x80800000,

	0x80008000, 0x80008000,		0x80000080, 0x80000080,
	0x80008000, 0x80008000,		0x80000080, 0x80000080
    };

    surface = cairo_image_surface_create_for_data ((unsigned char *) data,
						   CAIRO_FORMAT_ARGB32, 4, 4, 16);

    cairo_test_paint_checkered (cr);

    cairo_scale (cr, 4, 4);

    cairo_set_source_surface (cr, surface, 2 , 2);
    cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);
    cairo_paint (cr);

    cairo_surface_destroy (surface);

    return CAIRO_TEST_SUCCESS;
}

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