diff options
| -rw-r--r-- | src/cairo-image-source.c | 65 |
1 files changed, 55 insertions, 10 deletions
diff --git a/src/cairo-image-source.c b/src/cairo-image-source.c index c5bd228c4..661bc1068 100644 --- a/src/cairo-image-source.c +++ b/src/cairo-image-source.c @@ -554,24 +554,42 @@ _pixman_image_set_properties (pixman_image_t *pixman_image, } else { + double scale_x, scale_y; + int shrink_x, shrink_y; pixman_filter_t pixman_filter; + pixman_kernel_t pixman_kernel_sample, pixman_kernel_reconstruct; + + /* Compute scale factors as the length of basis vectors transformed by + * the pattern matrix. These scale factors are from user to pattern space, + * and as such they are greater than 1.0 for downscaling and less than 1.0 + * for upscaling. + * TODO: this approach may not be completely correct if the matrix + * contains a skew component. */ + scale_x = hypot (pattern->matrix.xx, pattern->matrix.yx); + scale_y = hypot (pattern->matrix.yx, pattern->matrix.yy); + + /* Use convolution filtering if the transformation shrinks the image + * by more than half a pixel */ + shrink_x = (extents->width / scale_x - extents->width) < -0.5; + shrink_y = (extents->height / scale_y - extents->height) < -0.5; switch (pattern->filter) { case CAIRO_FILTER_FAST: - pixman_filter = PIXMAN_FILTER_FAST; - break; - case CAIRO_FILTER_GOOD: - pixman_filter = PIXMAN_FILTER_GOOD; - break; - case CAIRO_FILTER_BEST: - pixman_filter = PIXMAN_FILTER_BEST; - break; case CAIRO_FILTER_NEAREST: pixman_filter = PIXMAN_FILTER_NEAREST; + pixman_kernel_sample = PIXMAN_KERNEL_IMPULSE; + pixman_kernel_reconstruct = PIXMAN_KERNEL_BOX; break; + case CAIRO_FILTER_GOOD: case CAIRO_FILTER_BILINEAR: pixman_filter = PIXMAN_FILTER_BILINEAR; + pixman_kernel_sample = PIXMAN_KERNEL_BOX; + pixman_kernel_reconstruct = PIXMAN_KERNEL_LINEAR; break; + case CAIRO_FILTER_BEST: + pixman_filter = PIXMAN_FILTER_BEST; + pixman_kernel_sample = PIXMAN_KERNEL_LANCZOS3; + pixman_kernel_reconstruct = PIXMAN_KERNEL_LANCZOS3; 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 @@ -579,10 +597,37 @@ _pixman_image_set_properties (pixman_image_t *pixman_image, * else inventing semantics and providing an actual * implementation for it. */ default: - pixman_filter = PIXMAN_FILTER_BEST; + pixman_filter = PIXMAN_FILTER_BILINEAR; + pixman_kernel_sample = PIXMAN_KERNEL_BOX; + pixman_kernel_reconstruct = PIXMAN_KERNEL_LINEAR; } - pixman_image_set_filter (pixman_image, pixman_filter, NULL, 0); + if (pixman_filter != PIXMAN_FILTER_NEAREST && (shrink_x || shrink_y)) { + pixman_kernel_t sampling_kernel_x, sampling_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; + + 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, + sampling_kernel_x, + sampling_kernel_y, + 1, 1); + + pixman_image_set_filter (pixman_image, + PIXMAN_FILTER_SEPARABLE_CONVOLUTION, + params, n_params); + + free (params); + } else { + pixman_image_set_filter (pixman_image, pixman_filter, NULL, 0); + } } { |