From: Søren Sandmann Pedersen <s...@redhat.com>
pixman_composite_trapezoids() is supposed to composite across the
entire destination, but it actually only composites across the extent
of the trapezoids. For operators such as ADD or OVER this doesn't
matter since a zero source has no effect on the destination. But for
operators such as SRC or IN, it does matter.
So for such operators where a zero source has an effect, don't clip to
the trap extents.
---
pixman/pixman-trap.c | 43 +++++++++++++++++++++++++++++++++++--------
test/composite-traps-test.c | 2 +-
2 files changed, 36 insertions(+), 9 deletions(-)
diff --git a/pixman/pixman-trap.c b/pixman/pixman-trap.c
index f633738..ab5c8c8 100644
--- a/pixman/pixman-trap.c
+++ b/pixman/pixman-trap.c
@@ -387,12 +387,43 @@ pixman_rasterize_trapezoid (pixman_image_t *
image,
}
}
+static const pixman_bool_t zero_src_has_no_effect[PIXMAN_N_OPERATORS] =
+{
+ FALSE, /* Clear 0 0 */
+ FALSE, /* Src 1 0 */
+ TRUE, /* Dst 0 1 */
+ TRUE, /* Over 1 1-Aa */
+ TRUE, /* OverReverse 1-Ab 1 */
+ FALSE, /* In Ab 0 */
+ FALSE, /* InReverse 0 Aa */
+ FALSE, /* Out 1-Ab 0 */
+ TRUE, /* OutReverse 0 1-Aa */
+ TRUE, /* Atop Ab 1-Aa */
+ FALSE, /* AtopReverse 1-Ab Aa */
+ TRUE, /* Xor 1-Ab 1-Aa */
+ TRUE, /* Add 1 1 */
+};
+
static pixman_bool_t
-get_trap_extents (pixman_op_t op, const pixman_trapezoid_t *traps, int n_traps,
+get_trap_extents (pixman_op_t op, pixman_image_t *dest,
+ const pixman_trapezoid_t *traps, int n_traps,
pixman_box32_t *box)
{
int i;
+ /* When the operator is such that a zero source has an
+ * effect on the underlying image, we have to
+ * composite across the entire destination
+ */
+ if (!zero_src_has_no_effect [op])
+ {
+ box->x1 = 0;
+ box->y1 = 0;
+ box->x2 = dest->bits.width;
+ box->y2 = dest->bits.height;
+ return TRUE;
+ }
+
box->x1 = INT32_MAX;
box->y1 = INT32_MAX;
box->x2 = INT32_MIN;
@@ -443,12 +474,8 @@ get_trap_extents (pixman_op_t op, const pixman_trapezoid_t
*traps, int n_traps,
* All the trapezoids are conceptually rendered to an infinitely big image.
* The (0, 0) coordinates of this image are then aligned with the (x, y)
* coordinates of the source image, and then both images are aligned with
- * the (x, y) coordinates of the destination. Then, in principle, compositing
- * of these three images takes place across the entire destination.
- *
- * FIXME: However, there is currently a bug, where we restrict this compositing
- * to the bounding box of the trapezoids. This is incorrect for operators such
- * as SRC and IN where blank source pixels do have an effect on the
destination.
+ * the (x, y) coordinates of the destination. Then these three images are
+ * composited across the entire destination.
*/
PIXMAN_EXPORT void
pixman_composite_trapezoids (pixman_op_t op,
@@ -491,7 +518,7 @@ pixman_composite_trapezoids (pixman_op_t op,
pixman_box32_t box;
int i;
- if (!get_trap_extents (op, traps, n_traps, &box))
+ if (!get_trap_extents (op, dst, traps, n_traps, &box))
return;
tmp = pixman_image_create_bits (
diff --git a/test/composite-traps-test.c b/test/composite-traps-test.c
index ff03b50..9fc94a4 100644
--- a/test/composite-traps-test.c
+++ b/test/composite-traps-test.c
@@ -251,6 +251,6 @@ test_composite (int testnum,
int
main (int argc, const char *argv[])
{
- return fuzzer_test_main("composite traps", 40000, 0xE3112106,
+ return fuzzer_test_main("composite traps", 40000, 0x33BFAA55,
test_composite, argc, argv);
}
--
1.7.4
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