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bgo#783835 - Don't divide by zero in box_blur_line() for gaussian blurs

We were making the decision to use box blurs, instead of a true
Gaussian kernel, based on the size of *both* x and y dimensions.  Do
them individually instead.
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federicomenaquintero committed Jun 27, 2017
1 parent 818ad22 commit ecf9267a24b2c3c0cd211dbdfa9ef2232511972a
Showing with 20 additions and 9 deletions.
  1. +20 −9 rsvg-filter.c
@@ -1417,6 +1417,8 @@ box_blur_line (gint box_width, gint even_offset,
kernel; it's the pixel to remove from the accumulator. */
gint *ac; /* Accumulator for each channel */

g_assert (box_width > 0);

ac = g_new0 (gint, bpp);

/* The algorithm differs for even and odd-sized kernels.
@@ -1774,7 +1776,6 @@ gaussian_blur_surface (cairo_surface_t *in,
gdouble sx,
gdouble sy)
{
gboolean use_box_blur;
gint width, height;
cairo_format_t in_format, out_format;
gint in_stride;
@@ -1818,14 +1819,6 @@ gaussian_blur_surface (cairo_surface_t *in,
if (sy < 0.0)
sy = 0.0;

/* For small radiuses, use a true gaussian kernel; otherwise use three box blurs with
* clever offsets.
*/
if (sx < 10.0 && sy < 10.0)
use_box_blur = FALSE;
else
use_box_blur = TRUE;

/* Bail out by just copying? */
if ((sx == 0.0 && sy == 0.0)
|| sx > 1000 || sy > 1000) {
@@ -1845,6 +1838,15 @@ gaussian_blur_surface (cairo_surface_t *in,
int y;
guchar *row_buffer = NULL;
guchar *row1, *row2;
gboolean use_box_blur;

/* For small radiuses, use a true gaussian kernel; otherwise use three box blurs with
* clever offsets.
*/
if (sx < 10.0)
use_box_blur = FALSE;
else
use_box_blur = TRUE;

if (use_box_blur) {
box_width = compute_box_blur_width (sx);
@@ -1900,6 +1902,15 @@ gaussian_blur_surface (cairo_surface_t *in,
guchar *col_buffer;
guchar *col1, *col2;
int x;
gboolean use_box_blur;

/* For small radiuses, use a true gaussian kernel; otherwise use three box blurs with
* clever offsets.
*/
if (sy < 10.0)
use_box_blur = FALSE;
else
use_box_blur = TRUE;

/* twice the size so we can have the source pixels and the blurred pixels */
col_buffer = g_new0 (guchar, height * bpp * 2);

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