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////////////////////////////////////////////////////////////////////////////////
//3456789 123456789 123456789 123456789 123456789 123456789 123456789 123456789
// 10 20 30 40 50 60 70 80
//
// raico-blur
//
// gaussian-blur.c - implements gaussian-blur function
//
// Copyright 2009 Canonical Ltd.
//
// Authors:
// Mirco "MacSlow" Mueller <mirco.mueller@canonical.com>
//
// Notes:
// based on filters in libpixman
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License version 3, as published
// by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranties of
// MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
// PURPOSE. See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////////////
#include <math.h>
#include <pixman.h>
#include "gaussian-blur.h"
pixman_fixed_t*
create_gaussian_blur_kernel (gint radius,
gdouble sigma,
gint* length)
{
const gdouble scale2 = 2.0f * sigma * sigma;
const gdouble scale1 = 1.0f / (G_PI * scale2);
const gint size = 2 * radius + 1;
const gint n_params = size * size;
pixman_fixed_t* params;
gdouble* tmp;
gdouble sum;
gint x;
gint y;
gint i;
tmp = g_newa (double, n_params);
// caluclate gaussian kernel in floating point format
for (i = 0, sum = 0, x = -radius; x <= radius; ++x) {
for (y = -radius; y <= radius; ++y, ++i) {
const gdouble u = x * x;
const gdouble v = y * y;
tmp[i] = scale1 * exp (-(u+v)/scale2);
sum += tmp[i];
}
}
// normalize gaussian kernel and convert to fixed point format
params = g_new (pixman_fixed_t, n_params + 2);
params[0] = pixman_int_to_fixed (size);
params[1] = pixman_int_to_fixed (size);
for (i = 0; i < n_params; ++i)
params[2 + i] = pixman_double_to_fixed (tmp[i] / sum);
if (length)
*length = n_params + 2;
return params;
}
void
_blur_image_surface (cairo_surface_t* surface,
gint radius,
gdouble sigma /* pass 0.0f for auto-calculation */)
{
pixman_fixed_t* params = NULL;
gint n_params;
pixman_image_t* src;
gint w;
gint h;
gint s;
gpointer p;
gdouble radiusf;
radiusf = fabs (radius) + 1.0f;
if (sigma == 0.0f)
sigma = sqrt (-(radiusf * radiusf) / (2.0f * log (1.0f / 255.0f)));
w = cairo_image_surface_get_width (surface);
h = cairo_image_surface_get_height (surface);
s = cairo_image_surface_get_stride (surface);
// create pixman image for cairo image surface
p = cairo_image_surface_get_data (surface);
src = pixman_image_create_bits (PIXMAN_a8r8g8b8, w, h, p, s);
// attach gaussian kernel to pixman image
params = create_gaussian_blur_kernel (radius, sigma, &n_params);
pixman_image_set_filter (src,
PIXMAN_FILTER_CONVOLUTION,
params,
n_params);
g_free (params);
// render blured image to new pixman image
pixman_image_composite (PIXMAN_OP_SRC,
src,
NULL,
src,
0,
0,
0,
0,
0,
0,
w,
h);
pixman_image_unref (src);
}
void
surface_gaussian_blur (cairo_surface_t* surface,
guint radius)
{
cairo_format_t format;
// sanity checks are done in raico-blur.c
// before we mess with the surface execute any pending drawing
cairo_surface_flush (surface);
format = cairo_image_surface_get_format (surface);
switch (format)
{
case CAIRO_FORMAT_ARGB32:
_blur_image_surface (surface, radius, 0.0f);
break;
case CAIRO_FORMAT_RGB24:
// do nothing, for now
break;
case CAIRO_FORMAT_A8:
// do nothing, for now
break;
default :
// do nothing
break;
}
// inform cairo we altered the surfaces contents
cairo_surface_mark_dirty (surface);
}
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