[cairo] [PATCH] Minor fixes in the new downscaling code.

[Krzysztof Kosiński]

This adresses issues brought up on the mailing list. If we use
a non-impulse samping kernel, there is no need to use anything
more sophisticated than box reconstruction. Similarly, using
a non-box reconstruction kernel is OK with impulse sampling.

Also addressed is PIXMAN_FILTER_BEST, which previously fell through
to the default case.
---
 src/cairo-image-source.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/cairo-image-source.c b/src/cairo-image-source.c
index 661bc10..254d6ba 100644
--- a/src/cairo-image-source.c
+++ b/src/cairo-image-source.c
@@ -590,6 +590,7 @@ _pixman_image_set_properties (pixman_image_t *pixman_image,
         pixman_filter = PIXMAN_FILTER_BEST;
         pixman_kernel_sample = PIXMAN_KERNEL_LANCZOS3;
         pixman_kernel_reconstruct = PIXMAN_KERNEL_LANCZOS3;
+        break;
     case CAIRO_FILTER_GAUSSIAN:
         /* XXX: The GAUSSIAN value has no implementation in cairo
          * whatsoever, so it was really a mistake to have it in the
@@ -604,18 +605,31 @@ _pixman_image_set_properties (pixman_image_t
*pixman_image,

     if (pixman_filter != PIXMAN_FILTER_NEAREST && (shrink_x || shrink_y)) {
         pixman_kernel_t sampling_kernel_x, sampling_kernel_y;
+        pixman_kernel_t reconstruction_kernel_x, reconstruction_kernel_y;
         int n_params;
         pixman_fixed_t *params;

-        sampling_kernel_x = shrink_x ? pixman_kernel_sample :
PIXMAN_KERNEL_IMPULSE;
-        sampling_kernel_y = shrink_y ? pixman_kernel_sample :
PIXMAN_KERNEL_IMPULSE;
+        if (shrink_x) {
+        samping_kernel_x = pixman_kernel_sample;
+        reconstruction_kernel_x = PIXMAN_KERNEL_BOX;
+        } else {
+        sampling_kernel_x = PIXMAN_KERNEL_IMPULSE;
+        reconstruction_kernel_x = pixman_kernel_reconstruct;
+        }
+        if (shrink_y) {
+        samping_kernel_y = pixman_kernel_sample;
+        reconstruction_kernel_y = PIXMAN_KERNEL_BOX;
+        } else {
+        sampling_kernel_y = PIXMAN_KERNEL_IMPULSE;
+        reconstruction_kernel_y = pixman_kernel_reconstruct;
+        }

         n_params = 0;
         params = pixman_filter_create_separable_convolution (&n_params,
                                  scale_x * 65536.0 + 0.5,
                                  scale_y * 65536.0 + 0.5,
-                                 pixman_kernel_reconstruct,
-                                 pixman_kernel_reconstruct,
+                                 reconstruction_kernel_x,
+                                 reconstruction_kernel_y,
                                  sampling_kernel_x,
                                  sampling_kernel_y,
                                  1, 1);
-- 
1.8.3.2