[cairo-commit] 2 commits - src/cairo-path-fixed.c src/cairo-slope-private.h test/Makefile.am test/Makefile.sources test/path-stroke-twice.c test/path-stroke-twice.ps.ref.png test/path-stroke-twice-ref.png
Chris Wilson
ickle at kemper.freedesktop.org
Tue Jan 12 09:08:15 PST 2010
src/cairo-path-fixed.c | 5 ++-
src/cairo-slope-private.h | 7 ++++
test/Makefile.am | 2 +
test/Makefile.sources | 1
test/path-stroke-twice-ref.png |binary
test/path-stroke-twice.c | 54 ++++++++++++++++++++++++++++++++++++++
test/path-stroke-twice.ps.ref.png |binary
7 files changed, 68 insertions(+), 1 deletion(-)
New commits:
commit 74ea4c908067f5579b51d3dbaea387da8f343671
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date: Tue Jan 12 17:00:25 2010 +0000
path: Do not remove anti-parallel line segments in case we are stroking
Bug 26010 - cairo_line_to optimizes away path segments
http://bugs.freedesktop.org/show_bug.cgi?id=26010
As exercised by path-stroke-twice, we incorrectly optimise away a line
segment if the path doubled back upon itself. This is very reminiscent
of the optimisation bug for replacing curve-to with line-to.
diff --git a/src/cairo-path-fixed.c b/src/cairo-path-fixed.c
index 42172c6..34de6a3 100644
--- a/src/cairo-path-fixed.c
+++ b/src/cairo-path-fixed.c
@@ -480,7 +480,10 @@ _cairo_path_fixed_line_to (cairo_path_fixed_t *path,
_cairo_slope_init (&prev, p, &path->current_point);
_cairo_slope_init (&self, &path->current_point, &point);
- if (_cairo_slope_equal (&prev, &self)) {
+ if (_cairo_slope_equal (&prev, &self) &&
+ /* cannot trim anti-parallel segments whilst stroking */
+ ! _cairo_slope_backwards (&prev, &self))
+ {
buf->points[buf->num_points - 1] = point;
goto FLAGS;
}
diff --git a/src/cairo-slope-private.h b/src/cairo-slope-private.h
index 4148c68..64f0dde 100644
--- a/src/cairo-slope-private.h
+++ b/src/cairo-slope-private.h
@@ -57,6 +57,13 @@ _cairo_slope_equal (const cairo_slope_t *a, const cairo_slope_t *b)
_cairo_int32x32_64_mul (b->dy, a->dx));
}
+static inline cairo_bool_t
+_cairo_slope_backwards (const cairo_slope_t *a, const cairo_slope_t *b)
+{
+ return _cairo_int64_negative (_cairo_int64_add (_cairo_int32x32_64_mul (a->dx, b->dx),
+ _cairo_int32x32_64_mul (a->dy, b->dy)));
+}
+
cairo_private int
_cairo_slope_compare (const cairo_slope_t *a,
const cairo_slope_t *b) cairo_pure;
commit a5dd5a6069c0d7435260a954d8d98483f5fbcc1c
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date: Tue Jan 12 16:32:09 2010 +0000
test: Add path-stroke-twice
Exercises a bug found by alois at astro.ch, whereby we inadvertently remove
a line segment when the path doubles back upon itself.
Bug 26010 - cairo_line_to optimizes away path segments
http://bugs.freedesktop.org/show_bug.cgi?id=26010
diff --git a/test/Makefile.am b/test/Makefile.am
index 581c30b..4e5b273 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -757,6 +757,8 @@ REFERENCE_IMAGES = \
pass-through.rgb24.ref.png \
path-append.ps.ref.png \
path-append.ref.png \
+ path-stroke-twice.ref.png \
+ path-stroke-twice.ps.ref.png \
path-append.test-fallback.ref.png \
path-append.xlib-fallback.ref.png \
path-append.xlib.ref.png \
diff --git a/test/Makefile.sources b/test/Makefile.sources
index 3b88056..0b4ba42 100644
--- a/test/Makefile.sources
+++ b/test/Makefile.sources
@@ -155,6 +155,7 @@ test_sources = \
paint-source-alpha.c \
paint-with-alpha.c \
path-append.c \
+ path-stroke-twice.c \
path-precision.c \
pattern-get-type.c \
pattern-getters.c \
diff --git a/test/path-stroke-twice-ref.png b/test/path-stroke-twice-ref.png
new file mode 100644
index 0000000..32ef630
Binary files /dev/null and b/test/path-stroke-twice-ref.png differ
diff --git a/test/path-stroke-twice.c b/test/path-stroke-twice.c
new file mode 100644
index 0000000..10bbbf8
--- /dev/null
+++ b/test/path-stroke-twice.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2010 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose. It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris at chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+/* Exercises a bug found by alois at astro.ch:
+ * http://bugs.freedesktop.org/show_bug.cgi?id=26010
+ * cairo_line_to optimizes away path segment
+ */
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+ cairo_set_source_rgb (cr, 1, 1, 1);
+ cairo_paint (cr);
+
+ cairo_set_source_rgb (cr, 0, 0, 0);
+ cairo_move_to (cr, 10, 10);
+ cairo_line_to (cr, 10, 20);
+ cairo_line_to (cr, 20, 30);
+ cairo_line_to (cr, 10, 20);
+ cairo_stroke (cr);
+
+ return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (path_stroke_twice,
+ "Tests stroking of a path containing a segment drawn twice",
+ "path, stroke", /* keywords */
+ NULL, /* requirements */
+ 40, 40,
+ NULL, draw)
diff --git a/test/path-stroke-twice.ps.ref.png b/test/path-stroke-twice.ps.ref.png
new file mode 100644
index 0000000..23e8147
Binary files /dev/null and b/test/path-stroke-twice.ps.ref.png differ
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