diff options
| author | Søren Sandmann Pedersen <soren.sandmann@gmail.com> | 2016-08-30 22:03:12 -0700 |
|---|---|---|
| committer | Søren Sandmann Pedersen <soren.sandmann@gmail.com> | 2016-09-02 00:40:12 -0400 |
| commit | 3b46fce6fec566e93a8a6b90df113272d203aafc (patch) | |
| tree | 51a1b131f919eec4e978f64aa13489a418045e47 | |
| parent | 8855b3a2a231ab348c02c0d92f0051b079eabfa3 (diff) | |
pixman-filter: Speed up BOX/BOX filter
The convolution of two BOX filters is simply the length of the
interval where both are non-zero, so we can simply return width from
the integral() function because the integration region has already
been restricted to be such that both functions are non-zero on it.
This is both faster and more accurate than doing numerical integration.
This patch is based on one by Bill Spitzak
https://lists.freedesktop.org/archives/pixman/2016-March/004446.html
with these changes:
- Rebased to not assume any changes in the arguments to integral().
- Dropped the multiplication by scale
- Added more details in the commit message.
Signed-off-by: Søren Sandmann <soren.sandmann@gmail.com>
Reviewed-by: Bill Spitzak <spitzak@gmail.com>
| -rw-r--r-- | pixman/pixman-filter.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c index 878cf9d..11e7d0e 100644 --- a/pixman/pixman-filter.c +++ b/pixman/pixman-filter.c @@ -160,11 +160,15 @@ integral (pixman_kernel_t kernel1, double x1, pixman_kernel_t kernel2, double scale, double x2, double width) { + if (kernel1 == PIXMAN_KERNEL_BOX && kernel2 == PIXMAN_KERNEL_BOX) + { + return width; + } /* The LINEAR filter is not differentiable at 0, so if the * integration interval crosses zero, break it into two * separate integrals. */ - if (kernel1 == PIXMAN_KERNEL_LINEAR && x1 < 0 && x1 + width > 0) + else if (kernel1 == PIXMAN_KERNEL_LINEAR && x1 < 0 && x1 + width > 0) { return integral (kernel1, x1, kernel2, scale, x2, - x1) + |