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/*
* Copyright © 2008 Kristian Høgsberg
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of the copyright holders not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. The copyright holders make no representations
* about the suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <cairo.h>
#include "cairo-util.h"
#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
void
blur_surface(cairo_surface_t *surface, int margin)
{
int32_t width, height, stride, x, y, z, w;
uint8_t *src, *dst;
uint32_t *s, *d, a, p;
int i, j, k, size, half;
uint8_t kernel[35];
double f;
size = ARRAY_LENGTH(kernel);
width = cairo_image_surface_get_width(surface);
height = cairo_image_surface_get_height(surface);
stride = cairo_image_surface_get_stride(surface);
src = cairo_image_surface_get_data(surface);
dst = malloc(height * stride);
half = size / 2;
a = 0;
for (i = 0; i < size; i++) {
f = (i - half);
kernel[i] = exp(- f * f / 30.0) * 80;
a += kernel[i];
}
for (i = 0; i < height; i++) {
s = (uint32_t *) (src + i * stride);
d = (uint32_t *) (dst + i * stride);
for (j = 0; j < width; j++) {
if (margin < j && j < width - margin) {
d[j] = s[j];
continue;
}
x = 0;
y = 0;
z = 0;
w = 0;
for (k = 0; k < size; k++) {
if (j - half + k < 0 || j - half + k >= width)
continue;
p = s[j - half + k];
x += (p >> 24) * kernel[k];
y += ((p >> 16) & 0xff) * kernel[k];
z += ((p >> 8) & 0xff) * kernel[k];
w += (p & 0xff) * kernel[k];
}
d[j] = (x / a << 24) | (y / a << 16) | (z / a << 8) | w / a;
}
}
for (i = 0; i < height; i++) {
s = (uint32_t *) (dst + i * stride);
d = (uint32_t *) (src + i * stride);
for (j = 0; j < width; j++) {
if (margin <= i && i < height - margin) {
d[j] = s[j];
continue;
}
x = 0;
y = 0;
z = 0;
w = 0;
for (k = 0; k < size; k++) {
if (i - half + k < 0 || i - half + k >= height)
continue;
s = (uint32_t *) (dst + (i - half + k) * stride);
p = s[j];
x += (p >> 24) * kernel[k];
y += ((p >> 16) & 0xff) * kernel[k];
z += ((p >> 8) & 0xff) * kernel[k];
w += (p & 0xff) * kernel[k];
}
d[j] = (x / a << 24) | (y / a << 16) | (z / a << 8) | w / a;
}
}
free(dst);
}
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