text-antialias-subpixel.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: Carl D. Worth <[e-mail]>
 */

#include "cairo-test.h"

#define WIDTH  31
#define HEIGHT 22
#define TEXT_SIZE 12

cairo_test_t test = {
    "text-antialias-subpixel",
    "Tests text rendering with subpixel antialiasing",
    WIDTH, HEIGHT
};

static cairo_test_status_t
draw (cairo_t *cr, int width, int height)
{
    cairo_text_extents_t extents;
    cairo_font_options_t *font_options;
    static char black[] = "black", blue[] = "blue";

    cairo_set_source_rgb (cr, 1.0, 1.0, 1.0);
    cairo_paint (cr);

    cairo_select_font_face (cr, "Bitstream Vera Sans",
			    CAIRO_FONT_SLANT_NORMAL,
			    CAIRO_FONT_WEIGHT_NORMAL);
    cairo_set_font_size (cr, TEXT_SIZE);

    /* Sub-pixel antialiasing with unhinted glyphs can be pretty ugly
     * (bad color fringing). The reason we turn off hints here is to
     * try to get repeatable glyph shapes on multiple systems, not for
     * any aesthetic reason. */
    font_options = cairo_font_options_create ();

    cairo_font_options_set_hint_style (font_options, CAIRO_HINT_STYLE_NONE);
    cairo_font_options_set_antialias (font_options, CAIRO_ANTIALIAS_SUBPIXEL);
    cairo_font_options_set_subpixel_order (font_options, CAIRO_SUBPIXEL_ORDER_RGB);
    cairo_set_font_options (cr, font_options);
    cairo_font_options_destroy (font_options);

    cairo_set_source_rgb (cr, 0, 0, 0); /* black */
    cairo_text_extents (cr, black, &extents);
    cairo_move_to (cr, -extents.x_bearing, -extents.y_bearing);
    cairo_show_text (cr, black);
    cairo_translate (cr, 0, -extents.y_bearing + 1);

    cairo_set_source_rgb (cr, 0, 0, 1); /* blue */
    cairo_text_extents (cr, blue, &extents);
    cairo_move_to (cr, -extents.x_bearing, -extents.y_bearing);
    cairo_show_text (cr, blue);

    return CAIRO_TEST_SUCCESS;
}

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