[cairo] [PATCH pixman 08/11] pixman-filter: fix blank images for IMPULSE sampling filter
Bill Spitzak
spitzak at gmail.com
Fri Sep 26 19:06:07 PDT 2014
- Put error on center of odd-sized filters. This may fix other filters
some but the primary effect is to change the size=1 filters produced
by IMPULSE sampling from 0.0 to 1.0.
- Made IMPULSE.IMPULSE produce a filter of size 1, not zero.
- Reuse the above result to produce a faster BOX.IMPULSE which
ignores the subsampling.
---
pixman/pixman-filter.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
index 1a465ac..d763138 100644
--- a/pixman/pixman-filter.c
+++ b/pixman/pixman-filter.c
@@ -230,6 +230,8 @@ filter_width (pixman_kernel_t reconstruct,
pixman_kernel_t sample,
double scale)
{
+ if (reconstruct == PIXMAN_KERNEL_BOX && sample == PIXMAN_KERNEL_IMPULSE)
+ return 0;
return ceil(scale * filters[sample].width + filters[reconstruct].width);
}
@@ -299,7 +301,7 @@ create_1d_filter (int width,
}
if (new_total != pixman_fixed_1)
- *(p - *width / 2) += (pixman_fixed_1 - new_total);
+ *(p - (width + 1) / 2) += (pixman_fixed_1 - new_total);
}
}
@@ -323,11 +325,13 @@ pixman_filter_create_separable_convolution (int *n_values,
int subsample_x, subsample_y;
int width, height;
- subsample_x = (1 << subsample_bits_x);
- subsample_y = (1 << subsample_bits_y);
-
width = filter_width (reconstruct_x, sample_x, sx);
+ if (width < 1) { width = 1; subsample_bits_x = 0; }
height = filter_width (reconstruct_y, sample_y, sy);
+ if (height < 1) { height = 1; subsample_bits_y = 0; }
+
+ subsample_x = (1 << subsample_bits_x);
+ subsample_y = (1 << subsample_bits_y);
*n_values = 4 + width * subsample_x + height * subsample_y;
--
1.7.9.5
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