static void
blur_rows (guchar *dst_buffer,
guchar *tmp_buffer,
int buffer_width,
int buffer_height,
int d)
{
int i;
for (i = 0; i < buffer_height; i++)
{
guchar *row = dst_buffer + i * buffer_width;
/* We want to produce a symmetric blur that spreads a pixel
* equally far to the left and right. If d is odd that happens
* naturally, but for d even, we approximate by using a blur
* on either side and then a centered blur of size d + 1.
* (technique also from the SVG specification)
*/
if (d % 2 == 1)
{
blur_xspan (row, tmp_buffer, buffer_width, d, 0);
blur_xspan (row, tmp_buffer, buffer_width, d, 0);
blur_xspan (row, tmp_buffer, buffer_width, d, 0);
}
else
{
blur_xspan (row, tmp_buffer, buffer_width, d, 1);
blur_xspan (row, tmp_buffer, buffer_width, d, -1);
blur_xspan (row, tmp_buffer, buffer_width, d + 1, 0);
}
}
}
static void
blur_rows (cairo_region_t *convolve_region,
int x_offset,
int y_offset,
guchar *buffer,
int buffer_width,
int buffer_height,
int d)
{
int i, j;
int n_rectangles;
guchar *tmp_buffer;
tmp_buffer = g_malloc (buffer_width);
n_rectangles = cairo_region_num_rectangles (convolve_region);
for (i = 0; i < n_rectangles; i++)
{
cairo_rectangle_int_t rect;
cairo_region_get_rectangle (convolve_region, i, &rect);
for (j = y_offset + rect.y; j < y_offset + rect.y + rect.height; j++)
{
guchar *row = buffer + j * buffer_width;
int x0 = x_offset + rect.x;
int x1 = x0 + rect.width;
/* We want to produce a symmetric blur that spreads a pixel
* equally far to the left and right. If d is odd that happens
* naturally, but for d even, we approximate by using a blur
* on either side and then a centered blur of size d + 1.
* (techique also from the SVG specification)
*/
if (d % 2 == 1)
{
blur_xspan (row, tmp_buffer, buffer_width, x0, x1, d, 0);
blur_xspan (row, tmp_buffer, buffer_width, x0, x1, d, 0);
blur_xspan (row, tmp_buffer, buffer_width, x0, x1, d, 0);
}
else
{
blur_xspan (row, tmp_buffer, buffer_width, x0, x1, d, 1);
blur_xspan (row, tmp_buffer, buffer_width, x0, x1, d, -1);
blur_xspan (row, tmp_buffer, buffer_width, x0, x1, d + 1, 0);
}
}
}
g_free (tmp_buffer);
}
