[cairo] [PATCH] fix transformation of device_transform

[Jeff Muizelaar]

The attached patches fix #16469 (https://bugs.freedesktop.org/show_bug.cgi?id=16469) by
transforming they pattern matrix by the device_transform matrix before
the inverse_ctm.

-Jeff
-------------- next part --------------
Add a test for scaling a surface with device offset.

From: Jeff Muizelaar <jmuizelaar at mozilla.com>


---

 test/Makefile.am                 |    2 +
 test/device-offset-scale-ref.png |  Bin
 test/device-offset-scale.c       |   81 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 83 insertions(+), 0 deletions(-)
 create mode 100644 test/device-offset-scale-ref.png
 create mode 100644 test/device-offset-scale.c

diff --git a/test/Makefile.am b/test/Makefile.am
index c7c265f..9554a28 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -41,6 +41,7 @@ degenerate-path$(EXEEXT)				\
 degenerate-pen$(EXEEXT)					\
 device-offset$(EXEEXT)					\
 device-offset-positive$(EXEEXT)				\
+device-offset-scale$(EXEEXT)				\
 extend-pad$(EXEEXT)					\
 extend-reflect$(EXEEXT)					\
 extend-reflect-similar$(EXEEXT)				\
@@ -369,6 +370,7 @@ REFERENCE_IMAGES = \
 	device-offset-positive-rgb24-ref.png	\
 	device-offset-ref.png	\
 	device-offset-rgb24-ref.png	\
+	device-offset-scale-ref.png	\
 	extend-pad-ref.png	\
 	extend-reflect-ref.png	\
 	extend-reflect-similar-ref.png	\
diff --git a/test/device-offset-scale-ref.png b/test/device-offset-scale-ref.png
new file mode 100644
index 0000000..66b2973
Binary files /dev/null and b/test/device-offset-scale-ref.png differ
diff --git a/test/device-offset-scale.c b/test/device-offset-scale.c
new file mode 100644
index 0000000..5134589
--- /dev/null
+++ b/test/device-offset-scale.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright ? 2008 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.
+ *
+ * Authors: Michael Ventnor, Jeff Muizelaar
+ */
+
+#include "cairo-test.h"
+
+#define WIDTH 20
+#define HEIGHT 20
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "device-offset-scale",
+    "Test that the device-offset transform is transformed by the ctm.",
+    WIDTH, HEIGHT,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_t *second_cr;
+    cairo_surface_t *second = cairo_image_surface_create (CAIRO_FORMAT_A8, 10, 10);
+
+    /* fill with black so we don't need an rgb test case */
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_paint (cr);
+
+    /* adjust the offset so that the second rectangle will fit on the surface */
+    cairo_surface_set_device_offset (second, -6, -6);
+
+    cairo_scale (cr, 0.5, 0.5);
+
+    /* draw the first rectangle */
+    cairo_set_source_rgb (cr, 0, 0, 0.4);
+    cairo_rectangle (cr, 6, 6, 10, 10);
+    cairo_fill (cr);
+
+    /* draw the second rectangle:
+     * this rectangle should end up in the same place as the rectangle above
+     * independent of the device offset of the surface it is painted on*/
+    second_cr = cairo_create (second);
+    cairo_rectangle (second_cr, 6, 6, 10, 10);
+    cairo_fill (second_cr);
+
+    /* paint the second rectangle on top of the first rectangle */
+    cairo_set_source_rgb (cr, 0.5, 0.5, 0);
+    cairo_mask_surface (cr, second, 0, 0);
+
+    cairo_destroy (second_cr);
+    cairo_surface_destroy (second);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
-------------- next part --------------
Fix scaling with a device offset

From: Jeff Muizelaar <jmuizelaar at mozilla.com>

Apply the device offset transformation to the pattern before the ctm one.
Fixes bug #16469.
---

 src/cairo-gstate.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/cairo-gstate.c b/src/cairo-gstate.c
index 0eb6e7d..4ba2873 100644
--- a/src/cairo-gstate.c
+++ b/src/cairo-gstate.c
@@ -795,8 +795,8 @@ _cairo_gstate_copy_transformed_pattern (cairo_gstate_t  *gstate,
     if (status)
 	return status;
 
-    _cairo_pattern_transform (pattern, ctm_inverse);
-
+    /* the device transform is applied first so that it is transformed by
+     * ctm_inverse */
     if (cairo_pattern_get_type (original) == CAIRO_PATTERN_TYPE_SURFACE) {
         surface_pattern = (cairo_surface_pattern_t *) original;
         surface = surface_pattern->surface;
@@ -804,6 +804,8 @@ _cairo_gstate_copy_transformed_pattern (cairo_gstate_t  *gstate,
             _cairo_pattern_transform (pattern, &surface->device_transform);
     }
 
+    _cairo_pattern_transform (pattern, ctm_inverse);
+
     return CAIRO_STATUS_SUCCESS;
 }