cairo/test/dash-offset-negative.c

   1 /*
   2  * Copyright © 2005 Red Hat, Inc.
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software
   5  * and its documentation for any purpose is hereby granted without
   6  * fee, provided that the above copyright notice appear in all copies
   7  * and that both that copyright notice and this permission notice
   8  * appear in supporting documentation, and that the name of
   9  * Red Hat, Inc. not be used in advertising or publicity pertaining to
  10  * distribution of the software without specific, written prior
  11  * permission. Red Hat, Inc. makes no representations about the
  12  * suitability of this software for any purpose.  It is provided "as
  13  * is" without express or implied warranty.
  14  *
  15  * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
  16  * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
  17  * FITNESS, IN NO EVENT SHALL RED HAT, INC. BE LIABLE FOR ANY SPECIAL,
  18  * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
  19  * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  20  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
  21  * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  22  *
  23  * Author: Owen Taylor <otaylor@redhat.com>
  24  */
  25
  26 #include "cairo-test.h"
  27
  28 #define IMAGE_WIDTH 19
  29 #define IMAGE_HEIGHT 19
  30
  31 /* Basic test of dashed strokes, including a test for the negative
  32  * dash offset bug:
  33  *
  34  *      https://bugs.freedesktop.org/show_bug.cgi?id=2729
  35  */
  36
  37 static cairo_test_draw_function_t draw;
  38
  39 static const cairo_test_t test = {
  40     "dash-offset-negative",
  41     "Tests cairo_set_dash with a negative offset",
  42     IMAGE_WIDTH, IMAGE_HEIGHT,
  43     draw
  44 };
  45
  46 static cairo_test_status_t
  47 draw (cairo_t *cr, int width, int height)
  48 {
  49     double dashes[] = { 1 };
  50
  51     /* We draw in the default black, so paint white first. */
  52     cairo_save (cr);
  53     cairo_set_source_rgb (cr, 1.0, 1.0, 1.0); /* white */
  54     cairo_paint (cr);
  55     cairo_restore (cr);
  56
  57     cairo_set_line_width (cr, 2);
  58
  59     /* Basic 1-1 dash pattern */
  60     cairo_set_dash (cr, dashes, 1, 0.);
  61
  62     cairo_move_to (cr,  1, 2);
  63     cairo_line_to (cr, 18, 2);
  64     cairo_stroke (cr);
  65
  66     /* Adjust path by 0.5. Ideally this would give a constant 50%
  67      * gray, (but does not due to the location of the regular sample
  68      * grid points. */
  69     cairo_move_to (cr, 1.5, 5);
  70     cairo_line_to (cr, 18., 5);
  71     cairo_stroke (cr);
  72
  73     /* Offset dash by 0.5, rather than the path */
  74     cairo_set_dash (cr, dashes, 1, 0.5);
  75
  76     cairo_move_to (cr,  1, 8);
  77     cairo_line_to (cr, 18, 8);
  78     cairo_stroke (cr);
  79
  80     /* Now, similar tests with negative dash offsets. */
  81
  82     /* Basic 1-1 dash pattern dashing */
  83     cairo_set_dash (cr, dashes, 1, -4);
  84
  85     cairo_move_to (cr,  1, 11);
  86     cairo_line_to (cr, 18, 11);
  87     cairo_stroke (cr);
  88
  89     /* Adjust path by 0.5 */
  90     cairo_move_to (cr, 1.5, 14);
  91     cairo_line_to (cr, 18., 14);
  92     cairo_stroke (cr);
  93
  94     /* Offset dash by 0.5 */
  95     cairo_set_dash (cr, dashes, 1, -3.5);
  96
  97     cairo_move_to (cr,  1, 17);
  98     cairo_line_to (cr, 18, 17);
  99     cairo_stroke (cr);
 100
 101     return CAIRO_TEST_SUCCESS;
 102 }
 103
 104 int
 105 main (void)
 106 {
 107     return cairo_test (&test);
 108 }