From: Bill Spitzak <spit...@gmail.com>
Only the triangle is discontinuous at 0. The other filters resemble a
cubic closely enough that Simpsons integration works without
splitting.
Changes by Søren: Rebase without the changes to the integral function,
update comment to match the new code.
Signed-off-by: Bill Spitzak <spit...@gmail.com>
Signed-off-by: Søren Sandmann <soren.sandm...@gmail.com>
Reviewed-by: Søren Sandmann <soren.sandm...@gmail.com>
---
pixman/pixman-filter.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
index ecff852..878cf9d 100644
--- a/pixman/pixman-filter.c
+++ b/pixman/pixman-filter.c
@@ -160,18 +160,17 @@ integral (pixman_kernel_t kernel1, double x1,
pixman_kernel_t kernel2, double scale, double x2,
double width)
{
- /* If the integration interval crosses zero, break it into
- * two separate integrals. This ensures that filters such
- * as LINEAR that are not differentiable at 0 will still
- * integrate properly.
+ /* The LINEAR filter is not differentiable at 0, so if the
+ * integration interval crosses zero, break it into two
+ * separate integrals.
*/
- if (x1 < 0 && x1 + width > 0)
+ if (kernel1 == PIXMAN_KERNEL_LINEAR && x1 < 0 && x1 + width > 0)
{
return
integral (kernel1, x1, kernel2, scale, x2, - x1) +
integral (kernel1, 0, kernel2, scale, x2 - x1, width + x1);
}
- else if (x2 < 0 && x2 + width > 0)
+ else if (kernel2 == PIXMAN_KERNEL_LINEAR && x2 < 0 && x2 + width > 0)
{
return
integral (kernel1, x1, kernel2, scale, x2, - x2) +
--
1.9.1
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