test/fill-and-stroke-alpha.c

   1 /*
   2  * Copyright © 2005 Red Hat, Inc.
   3  * Copyright © 2006 Red Hat, Inc.
   4  *
   5  * Permission to use, copy, modify, distribute, and sell this software
   6  * and its documentation for any purpose is hereby granted without
   7  * fee, provided that the above copyright notice appear in all copies
   8  * and that both that copyright notice and this permission notice
   9  * appear in supporting documentation, and that the name of
  10  * Red Hat, Inc. not be used in advertising or publicity pertaining to
  11  * distribution of the software without specific, written prior
  12  * permission. Red Hat, Inc. makes no representations about the
  13  * suitability of this software for any purpose.  It is provided "as
  14  * is" without express or implied warranty.
  15  *
  16  * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
  17  * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
  18  * FITNESS, IN NO EVENT SHALL RED HAT, INC. BE LIABLE FOR ANY SPECIAL,
  19  * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
  20  * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  21  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
  22  * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  23  *
  24  * Author: Carl D. Worth <cworth@cworth.org>
  25  */
  26
  27 #include "cairo-test.h"
  28
  29 #define PAD 2
  30 #define SIZE 10
  31
  32 static cairo_test_draw_function_t draw;
  33
  34 cairo_test_t test = {
  35     "fill-and-stroke-alpha",
  36     "Use a group to fill/stroke a path then blend the result with alpha onto the destination",
  37     2 * SIZE + 4 * PAD, SIZE + 2 * PAD,
  38     draw
  39 };
  40
  41 typedef void (*path_func_t) (cairo_t *cr);
  42
  43 static void
  44 rectangle (cairo_t *cr)
  45 {
  46     cairo_rectangle (cr, PAD, PAD, SIZE, SIZE);
  47 }
  48
  49 static void
  50 circle (cairo_t *cr)
  51 {
  52     cairo_arc (cr,
  53                PAD + SIZE / 2, PAD + SIZE / 2,
  54                SIZE / 2,
  55                0, 2 * M_PI);
  56 }
  57
  58 /* Given a path-generating function and two opaque patterns, fill and
  59  * stroke the path with the patterns (to an offscreen group), then
  60  * blend the result into the destination with the given alpha
  61  * value.
  62  */
  63 static void
  64 fill_and_stroke_alpha (cairo_t          *cr,
  65                        path_func_t       path_func,
  66                        cairo_pattern_t  *fill_pattern,
  67                        cairo_pattern_t  *stroke_pattern,
  68                        double            alpha)
  69 {
  70     cairo_push_group (cr);
  71     {
  72         (path_func) (cr);
  73         cairo_set_source (cr, fill_pattern);
  74         cairo_fill_preserve (cr);
  75         cairo_set_source (cr, stroke_pattern);
  76         cairo_stroke (cr);
  77     }
  78     cairo_pop_group_to_source (cr);
  79     cairo_paint_with_alpha (cr, alpha);
  80 }
  81
  82 static cairo_test_status_t
  83 draw (cairo_t *cr, int width, int height)
  84 {
  85     cairo_pattern_t *blue;
  86     cairo_pattern_t *red;
  87
  88     blue = cairo_pattern_create_rgb (0.0, 0.0, 1.0);
  89     red = cairo_pattern_create_rgb (1.0, 0.0, 0.0);
  90
  91     cairo_test_paint_checkered (cr);
  92
  93     fill_and_stroke_alpha (cr, rectangle, blue, red, 0.5);
  94
  95     cairo_translate (cr, SIZE + 2 * PAD, 0);
  96
  97     fill_and_stroke_alpha (cr, circle, red, blue, 0.5);
  98
  99     cairo_pattern_destroy (blue);
 100     cairo_pattern_destroy (red);
 101
 102     return CAIRO_TEST_SUCCESS;
 103 }
 104
 105 int
 106 main (void)
 107 {
 108     return cairo_test (&test);
 109 }