[cairo-commit] 2 commits - src/cairo.c test/.gitignore
test/line-width-scale.c test/line-width-scale-ps-argb32-ref.png
test/line-width-scale-ref.png test/Makefile.am
Carl Worth
cworth at kemper.freedesktop.org
Thu Apr 27 11:49:34 PDT 2006
src/cairo.c | 10 -
test/.gitignore | 1
test/Makefile.am | 2
test/line-width-scale-ps-argb32-ref.png |binary
test/line-width-scale-ref.png |binary
test/line-width-scale.c | 184 ++++++++++++++++++++++++++++++++
6 files changed, 192 insertions(+), 5 deletions(-)
New commits:
diff-tree 9729fe60246c7d98ddc1f690b924cd10daabf096 (from 5821d88119740dbbd489909f3bde2f41c7e7ce71)
Author: Carl Worth <cworth at cworth.org>
Date: Thu Apr 27 09:54:58 2006 -0700
Add line-width-scale test to demonstrate cairo_set_line_width bug
diff --git a/test/.gitignore b/test/.gitignore
index 67c0431..5ffa61d 100644
--- a/test/.gitignore
+++ b/test/.gitignore
@@ -33,6 +33,7 @@ imagediff
leaky-dash
leaky-polygon
line-width
+line-width-scale
linear-gradient
mask
mask-ctm
diff --git a/test/Makefile.am b/test/Makefile.am
index 965334e..3d459c4 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -28,6 +28,7 @@ gradient-alpha \
leaky-dash \
leaky-polygon \
line-width \
+line-width-scale \
linear-gradient \
mask \
mask-ctm \
@@ -144,6 +145,7 @@ leaky-dash-ref.png \
leaky-polygon-ref.png \
linear-gradient-ref.png \
line-width-ref.png \
+line-width-scale-ref.png \
mask-ctm-ref.png \
mask-ctm-rgb24-ref.png \
mask-ref.png \
diff --git a/test/line-width-scale-ps-argb32-ref.png b/test/line-width-scale-ps-argb32-ref.png
new file mode 100644
index 0000000..ab4d552
Binary files /dev/null and b/test/line-width-scale-ps-argb32-ref.png differ
diff --git a/test/line-width-scale-ref.png b/test/line-width-scale-ref.png
new file mode 100644
index 0000000..9f19759
Binary files /dev/null and b/test/line-width-scale-ref.png differ
diff --git a/test/line-width-scale.c b/test/line-width-scale.c
new file mode 100644
index 0000000..ec79a64
--- /dev/null
+++ b/test/line-width-scale.c
@@ -0,0 +1,184 @@
+/*
+ * 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 <cworth at cworth.org>
+ */
+
+#include "cairo-test.h"
+
+/* This test exercises the various interactions between
+ * cairo_set_line_width and cairo_scale. Specifically it show how
+ * separate transformations can affect the pen for stroking compared
+ * to the path itself.
+ *
+ * This was inspired by an image by Maxim Shemanarev demonstrating the
+ * flexible-pipeline nature of his Antigrain Geometry project:
+ *
+ * http://antigrain.com/tips/line_alignment/conv_order.gif
+ *
+ * It also uncovered a bug in cairo that cairo_set_line_width was not
+ * transforing the width according the the current CTM, but instead
+ * delaying that transformation until the time of cairo_stroke. See:
+ *
+ * http://article.gmane.org/gmane.comp.graphics.agg/2518
+ */
+
+#define LINE_WIDTH 13
+#define SPLINE 50.0
+#define XSCALE 0.5
+#define YSCALE 2.0
+#define WIDTH (XSCALE * SPLINE * 6.0)
+#define HEIGHT (YSCALE * SPLINE * 2.0)
+
+cairo_test_t test = {
+ "line-width-scale",
+ "Tests interaction of cairo_set_line_width with cairo_scale",
+ WIDTH, HEIGHT
+};
+
+static void
+spline_path (cairo_t *cr)
+{
+ cairo_save (cr);
+ {
+ cairo_move_to (cr,
+ - SPLINE, 0);
+ cairo_curve_to (cr,
+ - SPLINE / 4, - SPLINE,
+ SPLINE / 4, SPLINE,
+ SPLINE, 0);
+ }
+ cairo_restore (cr);
+}
+
+/* If we scale before setting the line width or creating the path,
+ * then obviously both will be scaled. */
+static void
+scale_then_set_line_width_and_stroke (cairo_t *cr)
+{
+ cairo_scale (cr, XSCALE, YSCALE);
+ cairo_set_line_width (cr, LINE_WIDTH);
+ spline_path (cr);
+ cairo_stroke (cr);
+}
+
+/* This is used to verify the results of
+ * scale_then_set_line_width_and_stroke.
+ *
+ * It uses save/restore pairs to isolate the scaling of the path and
+ * line_width and ensures that both are scaled.
+ */
+static void
+scale_path_and_line_width (cairo_t *cr)
+{
+ cairo_save (cr);
+ {
+ cairo_scale (cr, XSCALE, YSCALE);
+ spline_path (cr);
+ }
+ cairo_restore (cr);
+
+ cairo_save (cr);
+ {
+ cairo_scale (cr, XSCALE, YSCALE);
+ cairo_set_line_width (cr, LINE_WIDTH);
+ cairo_stroke (cr);
+ }
+ cairo_restore (cr);
+}
+
+/* This one's the bug.
+ *
+ * If we set the line width before scaling, then the path should be
+ * scaled but the line width should not.
+ *
+ * With the bug, the line_width is also being scaled here.
+ */
+static void
+set_line_width_then_scale_and_stroke (cairo_t *cr)
+{
+ cairo_set_line_width (cr, LINE_WIDTH);
+ cairo_scale (cr, XSCALE, YSCALE);
+ spline_path (cr);
+ cairo_stroke (cr);
+}
+
+/* This is used to verify what should be the results of
+ * set_line_width_then_scale_and_stroke (once the bug is fixed).
+ *
+ * It uses save/restore pairs to isolate the scaling of the path and
+ * line_width and ensures that the path is scaled while the line width
+ * is not.
+ */
+static void
+scale_path_not_line_width (cairo_t *cr)
+{
+ cairo_save (cr);
+ {
+ cairo_scale (cr, XSCALE, YSCALE);
+ spline_path (cr);
+ }
+ cairo_restore (cr);
+
+ cairo_save (cr);
+ {
+ cairo_set_line_width (cr, LINE_WIDTH);
+ cairo_stroke (cr);
+ }
+ cairo_restore (cr);
+}
+
+#define ARRAY_SIZE(arr) (sizeof(arr)/sizeof(arr[0]))
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+ int i;
+ typedef void (*figure_t) (cairo_t *cr);
+ figure_t figures[4] = {
+ scale_then_set_line_width_and_stroke,
+ scale_path_and_line_width,
+ set_line_width_then_scale_and_stroke,
+ scale_path_not_line_width
+ };
+
+ cairo_set_source_rgb (cr, 1.0, 1.0, 1.0); /* white */
+ cairo_paint (cr);
+ cairo_set_source_rgb (cr, 0.0, 0.0, 0.0); /* black */
+
+ for (i = 0; i < 4; i++) {
+ cairo_save (cr);
+ cairo_translate (cr,
+ WIDTH/4 + (i % 2) * WIDTH/2,
+ HEIGHT/4 + (i / 2) * HEIGHT/2);
+ (figures[i]) (cr);
+ cairo_restore (cr);
+ }
+
+ return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+ return cairo_test (&test, draw);
+}
diff-tree 5821d88119740dbbd489909f3bde2f41c7e7ce71 (from 5515191f84bb837383278495f1f7034e7a97bdce)
Author: Carl Worth <cworth at cworth.org>
Date: Thu Apr 27 11:45:26 2006 -0700
Correct documentation to say "user space", not "user-space" where appropriate.
diff --git a/src/cairo.c b/src/cairo.c
index 0f35fa6..70f1406 100644
--- a/src/cairo.c
+++ b/src/cairo.c
@@ -623,9 +623,9 @@ cairo_set_fill_rule (cairo_t *cr, cairo_
*
* Sets the current line width within the cairo context. The line
* width specifies the diameter of a pen that is circular in
- * user-space.
+ * user space.
*
- * As with the other stroke parameters, the current line cap style is
+ * As with the other stroke parameters, the current line width is
* examined by cairo_stroke(), cairo_stroke_extents(), and
* cairo_stroke_to_path(), but does not have any effect during path
* construction.
@@ -1131,9 +1131,9 @@ cairo_curve_to (cairo_t *cr,
* arc.
*
* Angles are measured in radians. An angle of 0.0 is in the direction
- * of the positive X axis (in user-space). An angle of %M_PI/2.0 radians
+ * of the positive X axis (in user space). An angle of %M_PI/2.0 radians
* (90 degrees) is in the direction of the positive Y axis (in
- * user-space). Angles increase in the direction from the positive X
+ * user space). Angles increase in the direction from the positive X
* axis toward the positive Y axis. So with the default transformation
* matrix, angles increase in a clockwise direction.
*
@@ -1144,7 +1144,7 @@ cairo_curve_to (cairo_t *cr,
* see cairo_arc_negative() to get the arc in the direction of
* decreasing angles.
*
- * The arc is circular in user-space. To achieve an elliptical arc,
+ * The arc is circular in user space. To achieve an elliptical arc,
* you can scale the current transformation matrix by different
* amounts in the X and Y directions. For example, to draw an ellipse
* in the box given by @x, @y, @width, @height:
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