[Pixman] [PATCH 11/14] pixman-filter: Speed up BOX/BOX filter

[Oded Gabbay]

On Tue, Apr 12, 2016 at 5:36 AM, Søren Sandmann Pedersen
<soren.sandmann at gmail.com> wrote:
> 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 at gmail.com>
> ---
>  pixman/pixman-filter.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
> index c868723..32aaa9a 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) +
> --
> 1.7.11.7
>
> _______________________________________________
> Pixman mailing list
> Pixman at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/pixman

This patch is:
Acked-by: Oded Gabbay <oded.gabbay at gmail.com>