--- /dev/null
+/*
+ * Copyright 2012, Red Hat, Inc.
+ * Copyright 2012, Soren Sandmann
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Author: Soren Sandmann <soren.sandmann@gmail.com>
+ */
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <assert.h>
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include "pixman-private.h"
+
+typedef double (* kernel_func_t) (double x);
+
+typedef struct
+{
+ pixman_kernel_t kernel;
+ kernel_func_t func;
+ double width;
+} filter_info_t;
+
+static double
+impulse_kernel (double x)
+{
+ return (x == 0.0)? 1.0 : 0.0;
+}
+
+static double
+box_kernel (double x)
+{
+ return 1;
+}
+
+static double
+linear_kernel (double x)
+{
+ return 1 - fabs (x);
+}
+
+static double
+gaussian_kernel (double x)
+{
+#define SQRT2 (1.4142135623730950488016887242096980785696718753769480)
+#define SIGMA (SQRT2 / 2.0)
+
+ return exp (- x * x / (2 * SIGMA * SIGMA)) / (SIGMA * sqrt (2.0 * M_PI));
+}
+
+static double
+sinc (double x)
+{
+ if (x == 0.0)
+ return 1.0;
+ else
+ return sin (M_PI * x) / (M_PI * x);
+}
+
+static double
+lanczos (double x, int n)
+{
+ return sinc (x) * sinc (x * (1.0 / n));
+}
+
+static double
+lanczos2_kernel (double x)
+{
+ return lanczos (x, 2);
+}
+
+static double
+lanczos3_kernel (double x)
+{
+ return lanczos (x, 3);
+}
+
+static double
+nice_kernel (double x)
+{
+ return lanczos3_kernel (x * 0.75);
+}
+
+static double
+general_cubic (double x, double B, double C)
+{
+ double ax = fabs(x);
+
+ if (ax < 1)
+ {
+ return ((12 - 9 * B - 6 * C) * ax * ax * ax +
+ (-18 + 12 * B + 6 * C) * ax * ax + (6 - 2 * B)) / 6;
+ }
+ else if (ax >= 1 && ax < 2)
+ {
+ return ((-B - 6 * C) * ax * ax * ax +
+ (6 * B + 30 * C) * ax * ax + (-12 * B - 48 * C) *
+ ax + (8 * B + 24 * C)) / 6;
+ }
+ else
+ {
+ return 0;
+ }
+}
+
+static double
+cubic_kernel (double x)
+{
+ /* This is the Mitchell-Netravali filter.
+ *
+ * (0.0, 0.5) would give us the Catmull-Rom spline,
+ * but that one seems to be indistinguishable from Lanczos2.
+ */
+ return general_cubic (x, 1/3.0, 1/3.0);
+}
+
+static const filter_info_t filters[] =
+{
+ { PIXMAN_KERNEL_IMPULSE, impulse_kernel, 0.0 },
+ { PIXMAN_KERNEL_BOX, box_kernel, 1.0 },
+ { PIXMAN_KERNEL_LINEAR, linear_kernel, 2.0 },
+ { PIXMAN_KERNEL_CUBIC, cubic_kernel, 4.0 },
+ { PIXMAN_KERNEL_GAUSSIAN, gaussian_kernel, 6 * SIGMA },
+ { PIXMAN_KERNEL_LANCZOS2, lanczos2_kernel, 4.0 },
+ { PIXMAN_KERNEL_LANCZOS3, lanczos3_kernel, 6.0 },
+ { PIXMAN_KERNEL_LANCZOS3_STRETCHED, nice_kernel, 8.0 },
+};
+
+/* This function scales @kernel2 by @scale, then
+ * aligns @x1 in @kernel1 with @x2 in @kernel2 and
+ * and integrates the product of the kernels across @width.
+ *
+ * This function assumes that the intervals are within
+ * the kernels in question. E.g., the caller must not
+ * try to integrate a linear kernel ouside of [-1:1]
+ */
+static double
+integral (pixman_kernel_t kernel1, double x1,
+ pixman_kernel_t kernel2, double scale, double x2,
+ double width)
+{
+ /* If the integration interval crosses zero, break it into
+ * two separate integrals. This ensures that filters such
+ * as LINEAR that are not differentiable at 0 will still
+ * integrate properly.
+ */
+ if (x1 < 0 && x1 + width > 0)
+ {
+ return
+ integral (kernel1, x1, kernel2, scale, x2, - x1) +
+ integral (kernel1, 0, kernel2, scale, x2 - x1, width + x1);
+ }
+ else if (x2 < 0 && x2 + width > 0)
+ {
+ return
+ integral (kernel1, x1, kernel2, scale, x2, - x2) +
+ integral (kernel1, x1 - x2, kernel2, scale, 0, width + x2);
+ }
+ else if (kernel1 == PIXMAN_KERNEL_IMPULSE)
+ {
+ assert (width == 0.0);
+ return filters[kernel2].func (x2 * scale);
+ }
+ else if (kernel2 == PIXMAN_KERNEL_IMPULSE)
+ {
+ assert (width == 0.0);
+ return filters[kernel1].func (x1);
+ }
+ else
+ {
+ /* Integration via Simpson's rule */
+#define N_SEGMENTS 128
+#define SAMPLE(a1, a2) \
+ (filters[kernel1].func ((a1)) * filters[kernel2].func ((a2) * scale))
+
+ double s = 0.0;
+ double h = width / (double)N_SEGMENTS;
+ int i;
+
+ s = SAMPLE (x1, x2);
+
+ for (i = 1; i < N_SEGMENTS; i += 2)
+ {
+ double a1 = x1 + h * i;
+ double a2 = x2 + h * i;
+
+ s += 2 * SAMPLE (a1, a2);
+
+ if (i >= 2 && i < N_SEGMENTS - 1)
+ s += 4 * SAMPLE (a1, a2);
+ }
+
+ s += SAMPLE (x1 + width, x2 + width);
+
+ return h * s * (1.0 / 3.0);
+ }
+}
+
+static pixman_fixed_t *
+create_1d_filter (int *width,
+ pixman_kernel_t reconstruct,
+ pixman_kernel_t sample,
+ double scale,
+ int n_phases)
+{
+ pixman_fixed_t *params, *p;
+ double step;
+ double size;
+ int i;
+
+ size = scale * filters[sample].width + filters[reconstruct].width;
+ *width = ceil (size);
+
+ p = params = malloc (*width * n_phases * sizeof (pixman_fixed_t));
+ if (!params)
+ return NULL;
+
+ step = 1.0 / n_phases;
+
+ for (i = 0; i < n_phases; ++i)
+ {
+ double frac = step / 2.0 + i * step;
+ pixman_fixed_t new_total;
+ int x, x1, x2;
+ double total;
+
+ /* Sample convolution of reconstruction and sampling
+ * filter. See rounding.txt regarding the rounding
+ * and sample positions.
+ */
+
+ x1 = ceil (frac - *width / 2.0 - 0.5);
+ x2 = x1 + *width;
+
+ total = 0;
+ for (x = x1; x < x2; ++x)
+ {
+ double pos = x + 0.5 - frac;
+ double rlow = - filters[reconstruct].width / 2.0;
+ double rhigh = rlow + filters[reconstruct].width;
+ double slow = pos - scale * filters[sample].width / 2.0;
+ double shigh = slow + scale * filters[sample].width;
+ double c = 0.0;
+ double ilow, ihigh;
+
+ if (rhigh >= slow && rlow <= shigh)
+ {
+ ilow = MAX (slow, rlow);
+ ihigh = MIN (shigh, rhigh);
+
+ c = integral (reconstruct, ilow,
+ sample, 1.0 / scale, ilow - pos,
+ ihigh - ilow);
+ }
+
+ total += c;
+ *p++ = (pixman_fixed_t)(c * 65536.0 + 0.5);
+ }
+
+ /* Normalize */
+ p -= *width;
+ total = 1 / total;
+ new_total = 0;
+ for (x = x1; x < x2; ++x)
+ {
+ pixman_fixed_t t = (*p) * total + 0.5;
+
+ new_total += t;
+ *p++ = t;
+ }
+
+ if (new_total != pixman_fixed_1)
+ *(p - *width / 2) += (pixman_fixed_1 - new_total);
+ }
+
+ return params;
+}
+
+/* Create the parameter list for a SEPARABLE_CONVOLUTION filter
+ * with the given kernels and scale parameters
+ */
+PIXMAN_EXPORT pixman_fixed_t *
+pixman_filter_create_separable_convolution (int *n_values,
+ pixman_fixed_t scale_x,
+ pixman_fixed_t scale_y,
+ pixman_kernel_t reconstruct_x,
+ pixman_kernel_t reconstruct_y,
+ pixman_kernel_t sample_x,
+ pixman_kernel_t sample_y,
+ int subsample_bits_x,
+ int subsample_bits_y)
+{
+ double sx = fabs (pixman_fixed_to_double (scale_x));
+ double sy = fabs (pixman_fixed_to_double (scale_y));
+ pixman_fixed_t *horz = NULL, *vert = NULL, *params = NULL;
+ int subsample_x, subsample_y;
+ int width, height;
+
+ subsample_x = (1 << subsample_bits_x);
+ subsample_y = (1 << subsample_bits_y);
+
+ horz = create_1d_filter (&width, reconstruct_x, sample_x, sx, subsample_x);
+ vert = create_1d_filter (&height, reconstruct_y, sample_y, sy, subsample_y);
+
+ if (!horz || !vert)
+ goto out;
+
+ *n_values = 4 + width * subsample_x + height * subsample_y;
+
+ params = malloc (*n_values * sizeof (pixman_fixed_t));
+ if (!params)
+ goto out;
+
+ params[0] = pixman_int_to_fixed (width);
+ params[1] = pixman_int_to_fixed (height);
+ params[2] = pixman_int_to_fixed (subsample_bits_x);
+ params[3] = pixman_int_to_fixed (subsample_bits_y);
+
+ memcpy (params + 4, horz,
+ width * subsample_x * sizeof (pixman_fixed_t));
+ memcpy (params + 4 + width * subsample_x, vert,
+ height * subsample_y * sizeof (pixman_fixed_t));
+
+out:
+ free (horz);
+ free (vert);
+
+ return params;
+}
Code Review / kvmfornfv.git / blobdiff