[Pixman] [PATCH pixman 15/15] pixman-image: Implement PIXMAN_FILTER_GOOD/BEST as separable convolutions
Bill Spitzak
spitzak at gmail.com
Wed Apr 29 12:05:03 PDT 2015
Detects and uses PIXMAN_FILTER_NEAREST for all 8 90-degree rotations and
reflections when the scale is 1.0 and integer translation.
GOOD uses:
scale < 1/16 : BOX.BOX at size 16
scale < 3/4 : BOX.BOX at size 1/scale
larger : BOX.BOX at size 1
If both directions have scale >= 3/4, or scale == 1/2 and an integer
translation, the faster PIXMAN_FILTER_BILINEAR code is used.
BEST uses:
scale < 1/24 : BOX.BOX at size 24
scale < 1/16 : BOX.BOX at size 1/scale
scale < 1 : IMPULSE.LANCZOS2 at size 1/scale
scale < 2 : IMPULSE.LANCZOS2 at size 1
scale < 128 : BOX.LANCZOS2 at size 1/(scale-1) (antialiased square pixels)
larger : BOX.LANCZOS2 at size 1/127 (antialias blur gets thicker)
---
pixman/pixman-image.c | 298 ++++++++++++++++++++++++++++++++++++-------------
1 file changed, 219 insertions(+), 79 deletions(-)
diff --git a/pixman/pixman-image.c b/pixman/pixman-image.c
index 1ff1a49..f7d74a1 100644
--- a/pixman/pixman-image.c
+++ b/pixman/pixman-image.c
@@ -28,6 +28,7 @@
#include <stdio.h>
#include <string.h>
#include <assert.h>
+#include <math.h>
#include "pixman-private.h"
@@ -274,112 +275,251 @@ compute_image_info (pixman_image_t *image)
FAST_PATH_X_UNIT_POSITIVE |
FAST_PATH_Y_UNIT_ZERO |
FAST_PATH_AFFINE_TRANSFORM);
+ switch (image->common.filter)
+ {
+ case PIXMAN_FILTER_CONVOLUTION:
+ break;
+ case PIXMAN_FILTER_SEPARABLE_CONVOLUTION:
+ flags |= FAST_PATH_SEPARABLE_CONVOLUTION_FILTER;
+ break;
+ default:
+ flags |= (FAST_PATH_NEAREST_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
+ break;
+ }
}
else
{
+ pixman_fixed_t (*m)[3] = image->common.transform->matrix;
+ double dx, dy;
+ int xsubsample, ysubsample;
+ int nearest_ok, bilinear_ok;
+
flags |= FAST_PATH_HAS_TRANSFORM;
- if (image->common.transform->matrix[2][0] == 0 &&
- image->common.transform->matrix[2][1] == 0 &&
- image->common.transform->matrix[2][2] == pixman_fixed_1)
+ nearest_ok = FALSE;
+ bilinear_ok = FALSE;
+
+ if (m[2][0] == 0 &&
+ m[2][1] == 0 &&
+ m[2][2] == pixman_fixed_1)
{
flags |= FAST_PATH_AFFINE_TRANSFORM;
- if (image->common.transform->matrix[0][1] == 0 &&
- image->common.transform->matrix[1][0] == 0)
+ if (m[0][1] == 0 && m[1][0] == 0)
{
- if (image->common.transform->matrix[0][0] == -pixman_fixed_1 &&
- image->common.transform->matrix[1][1] == -pixman_fixed_1)
+ flags |= FAST_PATH_SCALE_TRANSFORM;
+ if (abs(m[0][0]) == pixman_fixed_1 &&
+ abs(m[1][1]) == pixman_fixed_1)
{
- flags |= FAST_PATH_ROTATE_180_TRANSFORM;
+ nearest_ok = TRUE;
+ if (m[0][0] < 0 && m[1][1] < 0)
+ flags |= FAST_PATH_ROTATE_180_TRANSFORM;
}
- flags |= FAST_PATH_SCALE_TRANSFORM;
}
- else if (image->common.transform->matrix[0][0] == 0 &&
- image->common.transform->matrix[1][1] == 0)
+ else if (m[0][0] == 0 && m[1][1] == 0)
{
- pixman_fixed_t m01 = image->common.transform->matrix[0][1];
- pixman_fixed_t m10 = image->common.transform->matrix[1][0];
-
- if (m01 == -pixman_fixed_1 && m10 == pixman_fixed_1)
- flags |= FAST_PATH_ROTATE_90_TRANSFORM;
- else if (m01 == pixman_fixed_1 && m10 == -pixman_fixed_1)
- flags |= FAST_PATH_ROTATE_270_TRANSFORM;
+ if (abs(m[0][1]) == pixman_fixed_1 &&
+ abs(m[1][0]) == pixman_fixed_1)
+ {
+ nearest_ok = TRUE;
+ if (m[0][1] < 0 && m[1][0] > 0)
+ flags |= FAST_PATH_ROTATE_90_TRANSFORM;
+ else if (m[0][1] > 0 && m[1][0] < 0)
+ flags |= FAST_PATH_ROTATE_270_TRANSFORM;
+ }
}
}
- if (image->common.transform->matrix[0][0] > 0)
+ if (nearest_ok)
+ {
+ /* reject non-integer translation: */
+ if (pixman_fixed_frac (m[0][2] | m[1][2]))
+ nearest_ok = FALSE;
+ /* FIXME: there are some affine-test failures, showing
+ * that handling of BILINEAR and NEAREST filter is not
+ * quite equivalent when getting close to 32K for the
+ * translation components of the matrix. That's likely
+ * some bug, but for now just skip BILINEAR->NEAREST
+ * optimization in this case.
+ */
+ else if (abs(m[0][2] | m[1][2]) > pixman_int_to_fixed (30000))
+ nearest_ok = FALSE;
+ }
+
+ if (m[0][0] > 0)
flags |= FAST_PATH_X_UNIT_POSITIVE;
- if (image->common.transform->matrix[1][0] == 0)
+ if (m[1][0] == 0)
flags |= FAST_PATH_Y_UNIT_ZERO;
- }
- /* Filter */
- switch (image->common.filter)
- {
- case PIXMAN_FILTER_NEAREST:
- case PIXMAN_FILTER_FAST:
- flags |= (FAST_PATH_NEAREST_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
- break;
+ switch (image->common.filter)
+ {
+ case PIXMAN_FILTER_NEAREST:
+ case PIXMAN_FILTER_FAST:
+ flags |= (FAST_PATH_NEAREST_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
+ break;
- case PIXMAN_FILTER_BILINEAR:
- case PIXMAN_FILTER_GOOD:
- case PIXMAN_FILTER_BEST:
- flags |= (FAST_PATH_BILINEAR_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
+ case PIXMAN_FILTER_BILINEAR:
+ if (nearest_ok)
+ flags |= (FAST_PATH_NEAREST_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
+ else
+ flags |= (FAST_PATH_BILINEAR_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
+ break;
- /* Here we have a chance to optimize BILINEAR filter to NEAREST if
- * they are equivalent for the currently used transformation matrix.
- */
- if (flags & FAST_PATH_ID_TRANSFORM)
- {
- flags |= FAST_PATH_NEAREST_FILTER;
- }
- else if (
- /* affine and integer translation components in matrix ... */
- ((flags & FAST_PATH_AFFINE_TRANSFORM) &&
- !pixman_fixed_frac (image->common.transform->matrix[0][2] |
- image->common.transform->matrix[1][2])) &&
- (
- /* ... combined with a simple rotation */
- (flags & (FAST_PATH_ROTATE_90_TRANSFORM |
- FAST_PATH_ROTATE_180_TRANSFORM |
- FAST_PATH_ROTATE_270_TRANSFORM)) ||
- /* ... or combined with a simple non-rotated translation */
- (image->common.transform->matrix[0][0] == pixman_fixed_1 &&
- image->common.transform->matrix[1][1] == pixman_fixed_1 &&
- image->common.transform->matrix[0][1] == 0 &&
- image->common.transform->matrix[1][0] == 0)
- )
- )
- {
- /* FIXME: there are some affine-test failures, showing that
- * handling of BILINEAR and NEAREST filter is not quite
- * equivalent when getting close to 32K for the translation
- * components of the matrix. That's likely some bug, but for
- * now just skip BILINEAR->NEAREST optimization in this case.
+ case PIXMAN_FILTER_GOOD:
+ if (nearest_ok) {
+ flags |= (FAST_PATH_NEAREST_FILTER | FAST_PATH_NO_CONVOLUTION_FILTER);
+ break;
+ }
+
+ /* Compute filter sizes. This is the bounding box of a
+ * diameter=1 circle transformed by the matrix. Scaling
+ * down produces values greater than 1.
+ *
+ * For non-affine the circle is centered on one of the 4
+ * points 1,1 away from the origin. Which one depends on
+ * the signs of the values in the last row of the matrix,
+ * chosen to avoid dividing by zero.
+ *
+ * This division factor both accounts for the w component
+ * and converts from fixed to float.
*/
- pixman_fixed_t magic_limit = pixman_int_to_fixed (30000);
- if (image->common.transform->matrix[0][2] <= magic_limit &&
- image->common.transform->matrix[1][2] <= magic_limit &&
- image->common.transform->matrix[0][2] >= -magic_limit &&
- image->common.transform->matrix[1][2] >= -magic_limit)
- {
- flags |= FAST_PATH_NEAREST_FILTER;
+ dy = 1.0 / (abs(m[2][0]) + abs(m[2][1]) + abs(m[2][2]));
+ /* There are some signs that hypot is faster with numbers near 1
+ * so the division is done first. Mathematically it should work
+ * to divide afterwards.
+ */
+ dx = hypot (m[0][0] * dy, m[0][1] * dy);
+ dy = hypot (m[1][0] * dy, m[1][1] * dy);
+
+ /* scale < 1/16 : BOX.BOX at size 16
+ * scale < 3/4 : BOX.BOX at size 1/scale
+ * larger : BOX.BOX at size 1
+ *
+ * If both directions have a scale >= 3/4 or a scale of
+ * 1/2 and an integer translation, the faster
+ * PIXMAN_FILTER_BILINEAR code is used.
+ *
+ * Filter size is clamped to 16 to prevent extreme slowness.
+ */
+ if (dx <= 4.0 / 3) {
+ dx = 1.0;
+ bilinear_ok = TRUE;
+ } else if (dx > 16.0) {
+ dx = 16.0;
+ } else if (dx > 1.999 && dx < 2.001 &&
+ abs(m[0][0] * m[0][1]) < 4 &&
+ abs(pixman_fixed_frac(m[0][2]) < 2))
+ bilinear_ok = TRUE;
+ if (dy <= 4.0 / 3)
+ dy = 1.0;
+ else if (dy > 16.0) {
+ dy = 16.0;
+ bilinear_ok = FALSE;
+ } else if (bilinear_ok) {
+ if (dy > 1.999 && dy < 2.001 &&
+ abs(m[1][0] * m[1][1]) < 4 &&
+ abs(pixman_fixed_frac(m[1][2]) < 2))
+ ;
+ else bilinear_ok = FALSE;
+ }
+ if (bilinear_ok) {
+ flags |= (FAST_PATH_BILINEAR_FILTER |
+ FAST_PATH_NO_CONVOLUTION_FILTER);
+ break;
}
- }
- break;
- case PIXMAN_FILTER_CONVOLUTION:
- break;
+ xsubsample = 0;
+ while (dx * (1 << xsubsample) <= 128.0) xsubsample++;
+ ysubsample = 0;
+ while (dy * (1 << ysubsample) <= 128.0) ysubsample++;
+
+ if (image->common.filter_params)
+ free (image->common.filter_params);
+
+ image->common.filter_params =
+ pixman_filter_create_separable_convolution
+ ( & image->common.n_filter_params,
+ pixman_double_to_fixed(dx),
+ pixman_double_to_fixed(dy),
+ PIXMAN_KERNEL_BOX,
+ PIXMAN_KERNEL_BOX,
+ PIXMAN_KERNEL_BOX,
+ PIXMAN_KERNEL_BOX,
+ xsubsample, ysubsample);
+
+ flags |= FAST_PATH_SEPARABLE_CONVOLUTION_FILTER;
+ break;
- case PIXMAN_FILTER_SEPARABLE_CONVOLUTION:
- flags |= FAST_PATH_SEPARABLE_CONVOLUTION_FILTER;
- break;
+ case PIXMAN_FILTER_BEST:
+ if (nearest_ok) {
+ flags |= (FAST_PATH_NEAREST_FILTER |
+ FAST_PATH_NO_CONVOLUTION_FILTER);
+ break;
+ }
+ /* See notes above about filter sizes */
+ dy = 1.0 / (abs(m[2][0]) + abs(m[2][1]) + abs(m[2][2]));
+ dx = hypot (m[0][0] * dy, m[0][1] * dy);
+ dy = hypot (m[1][0] * dy, m[1][1] * dy);
+
+ /* scale < 1/24 : BOX.BOX at size 24
+ * scale < 1/16 : BOX.BOX at size 1/scale
+ * scale < 1 : IMPULSE.LANCZOS2 at size 1/scale
+ * scale < 2 : IMPULSE.LANCZOS2 at size 1
+ * scale < 128 : BOX.LANCZOS2 at size 1/(scale-1)
+ * larger : BOX.LANCZOS2 at size 1/127
+ *
+ * Filter switches to box and then clamps at 24 to prevent
+ * extreme slowness.
+ *
+ * When enlarging this produces square pixels with an
+ * anti-aliased border between them. At scales larger
+ * than 128x the antialias blur is increased to avoid
+ * making lots of subsamples.
+ */
+ if (dx > 24.0) dx = 24.0;
+ else if (dx >= 1.0) ;
+ else if (dx >= 0.5) dx = 1.0;
+ else if (dx > 1.0/128) dx /= 1.0 - dx;
+ else dx = 1.0/127;
+
+ xsubsample = 0;
+ while (dx * (1 << xsubsample) <= 128.0) xsubsample++;
+
+ if (dy > 24.0) dy = 24.0;
+ else if (dy >= 1.0) ;
+ else if (dy >= 0.5) dy = 1.0;
+ else if (dy > 1.0/128) dy /= 1.0 - dy;
+ else dy = 1.0/127;
+
+ ysubsample = 0;
+ while (dy * (1 << ysubsample) <= 128.0) ysubsample++;
+
+ image->common.filter_params =
+ pixman_filter_create_separable_convolution
+ ( & image->common.n_filter_params,
+ pixman_double_to_fixed(dx),
+ pixman_double_to_fixed(dy),
+ dx >= 1.0 && dx < 16.0 ? PIXMAN_KERNEL_IMPULSE : PIXMAN_KERNEL_BOX,
+ dy >= 1.0 && dy < 16.0 ? PIXMAN_KERNEL_IMPULSE : PIXMAN_KERNEL_BOX,
+ dx < 16.0 ? PIXMAN_KERNEL_LANCZOS2 : PIXMAN_KERNEL_BOX,
+ dy < 16.0 ? PIXMAN_KERNEL_LANCZOS2 : PIXMAN_KERNEL_BOX,
+ xsubsample, ysubsample);
+
+ flags |= FAST_PATH_SEPARABLE_CONVOLUTION_FILTER;
+ break;
- default:
- flags |= FAST_PATH_NO_CONVOLUTION_FILTER;
- break;
+ case PIXMAN_FILTER_CONVOLUTION:
+ break;
+
+ case PIXMAN_FILTER_SEPARABLE_CONVOLUTION:
+ flags |= FAST_PATH_SEPARABLE_CONVOLUTION_FILTER;
+ break;
+
+ default:
+ flags |= FAST_PATH_NO_CONVOLUTION_FILTER;
+ break;
+ }
}
/* Repeat mode */
--
1.7.9.5
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