GOOD uses the BOX filter, and uses BILINEAR for all scales > 1/1.35.
BEST uses the LANCZOS2 filter. The size is chosen to produce normal
filtering up to a scale of 2, and square pixels with only slight
blurry borders beyond that. I think it looks really nice.
Uses NEAREST instead of BILINEAR, GOOD, or BEST if possible. Including
reflections, which the previous code did not check for.
The scale demo has added a pulldown so you can test good/best, and
also compare separable filters with nearest and bilinear.
---
demos/scale.c | 14 ++-
demos/scale.ui | 40 +++++--
pixman/pixman-image.c | 275 +++++++++++++++++++++++++++++++++++--------------
3 files changed, 239 insertions(+), 90 deletions(-)
diff --git a/demos/scale.c b/demos/scale.c
index 0b6c715..c3ca753 100644
--- a/demos/scale.c
+++ b/demos/scale.c
@@ -68,6 +68,15 @@ typedef struct
int value;
} named_int_t;
+static const named_int_t filter_types[] =
+{
+ { "Separable", PIXMAN_FILTER_SEPARABLE_CONVOLUTION },
+ { "Nearest", PIXMAN_FILTER_NEAREST },
+ { "Bilinear", PIXMAN_FILTER_BILINEAR },
+ { "Good", PIXMAN_FILTER_GOOD },
+ { "Best", PIXMAN_FILTER_BEST },
+};
+
static const named_int_t filters[] =
{
{ "Box", PIXMAN_KERNEL_BOX },
@@ -201,7 +210,9 @@ rescale (GtkWidget *may_be_null, app_t *app)
gtk_adjustment_get_value (app->subsample_adjustment),
gtk_adjustment_get_value (app->subsample_adjustment));
- pixman_image_set_filter (app->original,
PIXMAN_FILTER_SEPARABLE_CONVOLUTION, params, n_params);
+ pixman_image_set_filter (app->original,
+ get_value (app, filter_types, "filter_combo_box"),
+ params, n_params);
pixman_image_set_repeat (
app->original, get_value (app, repeats, "repeat_combo_box"));
@@ -343,6 +354,7 @@ app_new (pixman_image_t *original)
widget = get_widget (app, "drawing_area");
g_signal_connect (widget, "expose_event", G_CALLBACK (on_expose), app);
+ set_up_combo_box (app, "filter_combo_box", G_N_ELEMENTS (filter_types),
filter_types);
set_up_filter_box (app, "reconstruct_x_combo_box");
set_up_filter_box (app, "reconstruct_y_combo_box");
set_up_filter_box (app, "sample_x_combo_box");
diff --git a/demos/scale.ui b/demos/scale.ui
index ee985dd..b62cbfb 100644
--- a/demos/scale.ui
+++ b/demos/scale.ui
@@ -191,12 +191,23 @@
<property name="column_spacing">8</property>
<property name="row_spacing">6</property>
<child>
+ <object class="GtkLabel" id="labelF">
+ <property name="visible">True</property>
+ <property name="xalign">1</property>
+ <property name="label"
translatable="yes"><b>Filter:</b></property>
+ <property name="use_markup">True</property>
+ </object>
+ </child>
+ <child>
<object class="GtkLabel" id="label4">
<property name="visible">True</property>
<property name="xalign">1</property>
<property name="label"
translatable="yes"><b>Reconstruct X:</b></property>
<property name="use_markup">True</property>
</object>
+ <packing>
+ <property name="top_attach">1</property>
+ </packing>
</child>
<child>
<object class="GtkLabel" id="label5">
@@ -206,7 +217,7 @@
<property name="use_markup">True</property>
</object>
<packing>
- <property name="top_attach">1</property>
+ <property name="top_attach">2</property>
</packing>
</child>
<child>
@@ -217,7 +228,7 @@
<property name="use_markup">True</property>
</object>
<packing>
- <property name="top_attach">2</property>
+ <property name="top_attach">3</property>
</packing>
</child>
<child>
@@ -228,7 +239,7 @@
<property name="use_markup">True</property>
</object>
<packing>
- <property name="top_attach">3</property>
+ <property name="top_attach">4</property>
</packing>
</child>
<child>
@@ -239,7 +250,7 @@
<property name="use_markup">True</property>
</object>
<packing>
- <property name="top_attach">4</property>
+ <property name="top_attach">5</property>
</packing>
</child>
<child>
@@ -250,7 +261,15 @@
<property name="use_markup">True</property>
</object>
<packing>
- <property name="top_attach">5</property>
+ <property name="top_attach">6</property>
+ </packing>
+ </child>
+ <child>
+ <object class="GtkComboBox" id="filter_combo_box">
+ <property name="visible">True</property>
+ </object>
+ <packing>
+ <property name="left_attach">1</property>
</packing>
</child>
<child>
@@ -259,6 +278,7 @@
</object>
<packing>
<property name="left_attach">1</property>
+ <property name="top_attach">1</property>
</packing>
</child>
<child>
@@ -267,7 +287,7 @@
</object>
<packing>
<property name="left_attach">1</property>
- <property name="top_attach">1</property>
+ <property name="top_attach">2</property>
</packing>
</child>
<child>
@@ -276,7 +296,7 @@
</object>
<packing>
<property name="left_attach">1</property>
- <property name="top_attach">2</property>
+ <property name="top_attach">3</property>
</packing>
</child>
<child>
@@ -285,7 +305,7 @@
</object>
<packing>
<property name="left_attach">1</property>
- <property name="top_attach">3</property>
+ <property name="top_attach">4</property>
</packing>
</child>
<child>
@@ -294,7 +314,7 @@
</object>
<packing>
<property name="left_attach">1</property>
- <property name="top_attach">4</property>
+ <property name="top_attach">5</property>
</packing>
</child>
<child>
@@ -304,7 +324,7 @@
</object>
<packing>
<property name="left_attach">1</property>
- <property name="top_attach">5</property>
+ <property name="top_attach">6</property>
</packing>
</child>
</object>
diff --git a/pixman/pixman-image.c b/pixman/pixman-image.c
index 1ff1a49..d7bfcf3 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 +275,228 @@ 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;
+
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;
+
+ 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);
+
+ /* At scales above 1/1.35 this uses the bilinear filter.
+ * This is identical to box at size 1, and I judged the
+ * artifacts for the smaller scales to not be worse than
+ * the box filter.
+ *
+ * Filters size is clamped to 16 to prevent extreme slowness.
+ */
+ if (dx <= 1.35) {
+ if (dy <= 1.35) {
+ flags |= (FAST_PATH_BILINEAR_FILTER |
+ FAST_PATH_NO_CONVOLUTION_FILTER);
+ break;
+ }
+ dx = 1.0;
+ } else if (dx > 16.0)
+ dx = 16.0;
+ if (dy <= 1.35)
+ dy = 1.0;
+ else if (dy > 16.0)
+ dy = 16.0;
+
+ 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),
+ dx < 1.35 ? PIXMAN_KERNEL_LINEAR : PIXMAN_KERNEL_BOX,
+ dy < 1.35 ? PIXMAN_KERNEL_LINEAR : PIXMAN_KERNEL_BOX,
+ dx < 1.35 ? PIXMAN_KERNEL_IMPULSE : PIXMAN_KERNEL_BOX,
+ dy < 1.35 ? PIXMAN_KERNEL_IMPULSE : PIXMAN_KERNEL_BOX,
+ xsubsample, ysubsample);
+
+ 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);
+
+ /* To prevent extreme slowness this switches to BOX at
+ * 1/16 scale and stops making the filter larger at 1/24
+ * scale.
+ *
+ * When enlarging this produces normal blur up to 2x, then
+ * square pixels with a 1-pixel blurry border between them
+ * for larger sizes. At scales larger than 128x the blur
+ * is increased to avoid making lots of subsamples.
+ */
+ if (dx > 24.0) dx = 24.0;
+ else if (dx < 1.0) {
+ if (dx >= 0.5) dx = 1.0;
+ else if (dx > 1.0/128) dx = 1.0 / (1.0 / dx - 1.0);
+ else dx = 1.0/127;
+ }
+ if (dy > 24.0) dy = 24.0;
+ else if (dy < 1.0) {
+ if (dy >= 0.5) dy = 1.0;
+ else if (dy > 1.0/128) dy = 1.0 / (1.0 / dy - 1.0);
+ else dy = 1.0/127;
}
- }
- break;
- case PIXMAN_FILTER_CONVOLUTION:
- break;
+ xsubsample = 0;
+ while (dx * (1 << xsubsample) <= 128.0) xsubsample++;
+ 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 ? PIXMAN_KERNEL_BOX : PIXMAN_KERNEL_IMPULSE,
+ dy < 1.0 ? PIXMAN_KERNEL_BOX : PIXMAN_KERNEL_IMPULSE,
+ 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;
- case PIXMAN_FILTER_SEPARABLE_CONVOLUTION:
- flags |= FAST_PATH_SEPARABLE_CONVOLUTION_FILTER;
- break;
+ case PIXMAN_FILTER_CONVOLUTION:
+ break;
- default:
- flags |= FAST_PATH_NO_CONVOLUTION_FILTER;
- 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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