[cairo] Offset artifacts using push/pop group api along with clip
T Rowley
tor at cs.brown.edu
Thu Aug 10 11:35:18 PDT 2006
In mozilla I'm implementing complex svg clipPaths by rendering both the
geometry and clipPath in seperate push/pop groups, then combining them
with cairo_mask_surface. This works fine when the whole surface is
being drawn, but when mozilla needs to do a partial redraw, I'm seeing
offset artifacts.
The attached testcase reproduces the problem as far as I can tell in the
cairo test framework. It also adds a
cairo_surface_pattern_get_surface() API to get access to a surface
inside a pattern.
-------------- next part --------------
diff --git a/src/cairo-pattern.c b/src/cairo-pattern.c
index ebdb13638b18944b57d76b687a800e5dfd00d857..268e0faab03f5bdcd44c5d08716d76308f1885d1 100644
--- a/src/cairo-pattern.c
+++ b/src/cairo-pattern.c
@@ -778,6 +778,26 @@ cairo_pattern_get_matrix (cairo_pattern_
*matrix = pattern->matrix;
}
+/**
+ * cairo_surface_pattern_get_surface:
+ * @pattern: a #cairo_pattern_t
+ *
+ * Returns the underlying surface of a surface pattern, null if
+ * non-surface pattern.
+ **/
+cairo_surface_t *
+cairo_surface_pattern_get_surface (cairo_pattern_t *pattern)
+{
+ cairo_surface_t *surface;
+
+ if (pattern == NULL || pattern->type != CAIRO_PATTERN_TYPE_SURFACE)
+ return NULL;
+
+ surface = ((cairo_surface_pattern_t *) pattern)->surface;
+ cairo_surface_reference(surface);
+ return surface;
+}
+
void
cairo_pattern_set_filter (cairo_pattern_t *pattern, cairo_filter_t filter)
{
diff --git a/src/cairo.h b/src/cairo.h
index bac27fdb588048f812a2fd37f2f468474dba2423..a8c282c7395ace3a5e7a9cbde0b3a52cd78a5d3c 100644
--- a/src/cairo.h
+++ b/src/cairo.h
@@ -1508,6 +1508,9 @@ cairo_public void
cairo_pattern_get_matrix (cairo_pattern_t *pattern,
cairo_matrix_t *matrix);
+cairo_public cairo_surface_t *
+cairo_surface_pattern_get_surface (cairo_pattern_t *pattern);
+
/**
* cairo_extend_t
* @CAIRO_EXTEND_NONE: pixels outside of the source pattern
diff --git a/test/Makefile.am b/test/Makefile.am
index 968e0908b67e5a319bf9f8978e6c64818ce33848..21c208436fdd8b024e26cd666a6c7116dc4a144c 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -82,7 +82,8 @@ unbounded-operator \
user-data \
rel-path \
push-group \
-zero-alpha
+zero-alpha \
+push-group-clip
# Then we have a collection of tests that are only run if certain
# features are compiled into cairo
@@ -268,6 +269,8 @@ push-group-ref.png \
push-group-rgb24-ref.png \
push-group-svg-argb32-ref.png \
push-group-svg-rgb24-ref.png \
+push-group-clip-ref.png \
+push-group-clip-rgb24-ref.png \
rectangle-rounding-error-ref.png \
rel-path-ref.png \
rel-path-rgb24-ref.png \
diff --git a/test/push-group-clip-ref.png b/test/push-group-clip-ref.png
new file mode 100644
index 0000000000000000000000000000000000000000..d679ee5f279f962222f75e2ce7a1746af2cf9d82
GIT binary patch
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diff --git a/test/push-group-clip-rgb24-ref.png b/test/push-group-clip-rgb24-ref.png
new file mode 100644
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GIT binary patch
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diff --git a/test/push-group-clip.c b/test/push-group-clip.c
new file mode 100644
index 0000000000000000000000000000000000000000..d6aed8b8fd299e922a34cb344d6549b2099869c0
--- /dev/null
+++ b/test/push-group-clip.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright © 2005 Mozilla Corporation
+ *
+ * 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
+ * Mozilla Corporation not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Mozilla Corporation makes no representations about the
+ * suitability of this software for any purpose. It is provided "as
+ * is" without express or implied warranty.
+ *
+ * MOZILLA CORPORATION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL MOZILLA CORPORATION 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: Vladimir Vukicevic <vladimir at pobox.com>
+ */
+
+#include "cairo-test.h"
+
+#define UNIT_SIZE 100
+
+#define WIDTH UNIT_SIZE
+#define HEIGHT UNIT_SIZE
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+ "push-group-clip",
+ "Verify that cairo_push_group works with clipping.",
+ WIDTH, HEIGHT,
+ draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+ cairo_pattern_t *mask;
+ cairo_surface_t *maskSurface;
+
+ cairo_save (cr);
+
+ /* NOTE: #if 0 out the follow to see working mask clipping */
+#if 1
+ /* Mozilla style partial redraws are setup in this sort of fashion */
+ cairo_translate (cr, -UNIT_SIZE/2, 0);
+
+ cairo_rectangle (cr, UNIT_SIZE/2, 0, UNIT_SIZE/2, UNIT_SIZE);
+ cairo_clip (cr);
+ cairo_new_path (cr);
+#endif
+
+ /* start a group */
+ cairo_push_group (cr);
+
+ /* draw diamond */
+ cairo_move_to (cr, UNIT_SIZE / 2, 0);
+ cairo_line_to (cr, UNIT_SIZE , UNIT_SIZE / 2);
+ cairo_line_to (cr, UNIT_SIZE / 2, UNIT_SIZE);
+ cairo_line_to (cr, 0 , UNIT_SIZE / 2);
+ cairo_close_path (cr);
+ cairo_set_source_rgba (cr, 0, 0, 1, 1);
+ cairo_fill (cr);
+
+ /* draw circle */
+ cairo_arc (cr,
+ UNIT_SIZE / 2, UNIT_SIZE / 2,
+ UNIT_SIZE / 3.5,
+ 0, M_PI * 2);
+ cairo_set_source_rgba (cr, 1, 0, 0, 1);
+ cairo_fill (cr);
+
+ cairo_pop_group_to_source (cr);
+
+ /* NOTE: toggle this #if to see normal clipping instead of masking */
+#if 1
+ /* start mask group */
+ cairo_push_group (cr);
+
+ /* draw rect - horizontal clipping bar*/
+ cairo_rectangle (cr,
+ 0, UNIT_SIZE/4,
+ UNIT_SIZE, UNIT_SIZE/2);
+ cairo_set_source_rgba (cr, 1, 1, 1, 1);
+ cairo_fill (cr);
+
+ mask = cairo_pop_group (cr);
+ maskSurface = cairo_surface_pattern_get_surface(mask);
+
+ cairo_mask_surface (cr, maskSurface, 0, 0);
+
+ cairo_surface_destroy (maskSurface);
+ cairo_pattern_destroy (mask);
+#else
+ cairo_rectangle (cr,
+ 0, UNIT_SIZE/4,
+ UNIT_SIZE, UNIT_SIZE/2);
+ cairo_clip (cr);
+ cairo_new_path (cr);
+
+ cairo_paint (cr);
+#endif
+
+ cairo_restore (cr);
+
+ return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+ return cairo_test (&test);
+}
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