/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* gimpbrush-transform.c
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY 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 .
*/
#include "config.h"
#include
#include
#include "libgimpmath/gimpmath.h"
#include "core-types.h"
#include "gegl/gimp-gegl-loops.h"
#include "gimpbrush.h"
#include "gimpbrush-transform.h"
#include "gimptempbuf.h"
#define MAX_BLUR_KERNEL 15
/* local function prototypes */
static void gimp_brush_transform_bounding_box (GimpTempBuf *brush,
const GimpMatrix3 *matrix,
gint *x,
gint *y,
gint *width,
gint *height);
static gdouble gimp_brush_transform_array_sum (gfloat *arr,
gint len);
static void gimp_brush_transform_fill_blur_kernel (gfloat *arr,
gint len);
static gint gimp_brush_transform_blur_kernel_size (gint height,
gint width,
gdouble hardness);
/* public functions */
void
gimp_brush_real_transform_size (GimpBrush *brush,
gdouble scale,
gdouble aspect_ratio,
gdouble angle,
gint *width,
gint *height)
{
GimpMatrix3 matrix;
gint x, y;
gimp_brush_transform_matrix (gimp_temp_buf_get_width (brush->mask),
gimp_temp_buf_get_height (brush->mask),
scale, aspect_ratio, angle, &matrix);
gimp_brush_transform_bounding_box (brush->mask, &matrix, &x, &y, width, height);
}
/*
* Transforms the brush mask with bilinear interpolation.
*
* Rather than calculating the inverse transform for each point in the
* transformed image, this algorithm uses the inverse transformed
* corner points of the destination image to work out the starting
* position in the source image and the U and V deltas in the source
* image space. It then uses a scan-line approach, looping through
* rows and colummns in the transformed (destination) image while
* walking along the corresponding rows and columns (named U and V) in
* the source image.
*
* The horizontal in destination space (transform result) is reverse
* transformed into source image space to get U. The vertical in
* destination space (transform result) is reverse transformed into
* source image space to get V.
*
* The strength of this particular algorithm is that calculation work
* should depend more upon the final transformed brush size rather
* than the input brush size.
*
* There are no floating point calculations in the inner loop for speed.
*
* Some variables end with the suffix _i to indicate they have been
* premultiplied by int_multiple
*/
GimpTempBuf *
gimp_brush_real_transform_mask (GimpBrush *brush,
gdouble scale,
gdouble aspect_ratio,
gdouble angle,
gdouble hardness)
{
GimpTempBuf *result;
GimpTempBuf *source;
guchar *dest;
const guchar *src;
GimpMatrix3 matrix;
gint src_width;
gint src_height;
gint src_width_minus_one;
gint src_height_minus_one;
gint dest_width;
gint dest_height;
gint x, y;
gdouble blx, brx, tlx, trx;
gdouble bly, bry, tly, try;
gdouble src_tl_to_tr_delta_x;
gdouble src_tl_to_tr_delta_y;
gdouble src_tl_to_bl_delta_x;
gdouble src_tl_to_bl_delta_y;
gint src_walk_ux_i;
gint src_walk_uy_i;
gint src_walk_vx_i;
gint src_walk_vy_i;
gint src_space_cur_pos_x;
gint src_space_cur_pos_y;
gint src_space_cur_pos_x_i;
gint src_space_cur_pos_y_i;
gint src_space_row_start_x_i;
gint src_space_row_start_y_i;
const guchar *src_walker;
const guchar *pixel_next;
const guchar *pixel_below;
const guchar *pixel_below_next;
gint opposite_x, distance_from_true_x;
gint opposite_y, distance_from_true_y;
/*
* tl, tr etc are used because it is easier to visualize top left,
* top right etc corners of the forward transformed source image
* rectangle.
*/
const gint fraction_bits = 12;
const gint int_multiple = pow (2, fraction_bits);
/* In inner loop's bilinear calculation, two numbers that were each
* previously multiplied by int_multiple are multiplied together.
* To get back the right result, the multiplication result must be
* divided *twice* by 2^fraction_bits, equivalent to bit shift right
* by 2 * fraction_bits
*/
const gint recovery_bits = 2 * fraction_bits;
/*
* example: suppose fraction_bits = 9
* a 9-bit mask looks like this: 0001 1111 1111
* and is given by: 2^fraction_bits - 1
* demonstration:
* 2^0 = 0000 0000 0001
* 2^1 = 0000 0000 0010
* :
* 2^8 = 0001 0000 0000
* 2^9 = 0010 0000 0000
* 2^9 - 1 = 0001 1111 1111
*/
const guint fraction_bitmask = pow(2, fraction_bits) - 1 ;
source = brush->mask;
src_width = gimp_temp_buf_get_width (source);
src_height = gimp_temp_buf_get_height (source);
gimp_brush_transform_matrix (src_width, src_height,
scale, aspect_ratio, angle, &matrix);
if (gimp_matrix3_is_identity (&matrix))
return gimp_temp_buf_copy (source);
src_width_minus_one = src_width - 1;
src_height_minus_one = src_height - 1;
gimp_brush_transform_bounding_box (source, &matrix,
&x, &y, &dest_width, &dest_height);
gimp_matrix3_translate (&matrix, -x, -y);
gimp_matrix3_invert (&matrix);
result = gimp_temp_buf_new (dest_width, dest_height,
gimp_temp_buf_get_format (brush->mask));
dest = gimp_temp_buf_get_data (result);
src = gimp_temp_buf_get_data (source);
/* prevent disappearance of 1x1 pixel brush at some rotations when
scaling < 1 */
/*
if (src_width == 1 && src_height == 1 && scale_x < 1 && scale_y < 1 )
{
*dest = src[0];
return result;
}*/
gimp_matrix3_transform_point (&matrix, 0, 0, &tlx, &tly);
gimp_matrix3_transform_point (&matrix, dest_width, 0, &trx, &try);
gimp_matrix3_transform_point (&matrix, 0, dest_height, &blx, &bly);
gimp_matrix3_transform_point (&matrix, dest_width, dest_height, &brx, &bry);
/* in image space, calc U (what was horizontal originally)
* note: double precision
*/
src_tl_to_tr_delta_x = trx - tlx;
src_tl_to_tr_delta_y = try - tly;
/* in image space, calc V (what was vertical originally)
* note: double precision
*/
src_tl_to_bl_delta_x = blx - tlx;
src_tl_to_bl_delta_y = bly - tly;
/* speed optimized, note conversion to int precision */
src_walk_ux_i = (gint) ((src_tl_to_tr_delta_x / dest_width) * int_multiple);
src_walk_uy_i = (gint) ((src_tl_to_tr_delta_y / dest_width) * int_multiple);
src_walk_vx_i = (gint) ((src_tl_to_bl_delta_x / dest_height) * int_multiple);
src_walk_vy_i = (gint) ((src_tl_to_bl_delta_y / dest_height) * int_multiple);
/* initialize current position in source space to the start position (tl)
* speed optimized, note conversion to int precision
*/
src_space_cur_pos_x_i = (gint) (tlx* int_multiple);
src_space_cur_pos_y_i = (gint) (tly* int_multiple);
src_space_cur_pos_x = (gint) (src_space_cur_pos_x_i >> fraction_bits);
src_space_cur_pos_y = (gint) (src_space_cur_pos_y_i >> fraction_bits);
src_space_row_start_x_i = (gint) (tlx* int_multiple);
src_space_row_start_y_i = (gint) (tly* int_multiple);
for (y = 0; y < dest_height; y++)
{
for (x = 0; x < dest_width; x++)
{
if (src_space_cur_pos_x > src_width_minus_one ||
src_space_cur_pos_x < 0 ||
src_space_cur_pos_y > src_height_minus_one ||
src_space_cur_pos_y < 0)
/* no corresponding pixel in source space */
{
*dest = 0;
}
else /* reverse transformed point hits source pixel */
{
src_walker = src
+ src_space_cur_pos_y * src_width
+ src_space_cur_pos_x;
/* bottom right corner
* no pixel below, reuse current pixel instead
* no next pixel to the right so reuse current pixel instead
*/
if (src_space_cur_pos_y == src_height_minus_one &&
src_space_cur_pos_x == src_width_minus_one )
{
pixel_next = src_walker;
pixel_below = src_walker;
pixel_below_next = src_walker;
}
/* bottom edge pixel row, except rightmost corner
* no pixel below, reuse current pixel instead */
else if (src_space_cur_pos_y == src_height_minus_one)
{
pixel_next = src_walker + 1;
pixel_below = src_walker;
pixel_below_next = src_walker + 1;
}
/* right edge pixel column, except bottom corner
* no next pixel to the right so reuse current pixel instead */
else if (src_space_cur_pos_x == src_width_minus_one)
{
pixel_next = src_walker;
pixel_below = src_walker + src_width;
pixel_below_next = pixel_below;
}
/* neither on bottom edge nor on right edge */
else
{
pixel_next = src_walker + 1;
pixel_below = src_walker + src_width;
pixel_below_next = pixel_below + 1;
}
distance_from_true_x = src_space_cur_pos_x_i & fraction_bitmask;
distance_from_true_y = src_space_cur_pos_y_i & fraction_bitmask;
opposite_x = int_multiple - distance_from_true_x;
opposite_y = int_multiple - distance_from_true_y;
*dest = ((src_walker[0] * opposite_x +
pixel_next[0] * distance_from_true_x) * opposite_y +
(pixel_below[0] * opposite_x +
pixel_below_next[0] *distance_from_true_x) * distance_from_true_y
) >> recovery_bits;
}
src_space_cur_pos_x_i+=src_walk_ux_i;
src_space_cur_pos_y_i+=src_walk_uy_i;
src_space_cur_pos_x = src_space_cur_pos_x_i >> fraction_bits;
src_space_cur_pos_y = src_space_cur_pos_y_i >> fraction_bits;
dest ++;
} /* end for x */
src_space_row_start_x_i +=src_walk_vx_i;
src_space_row_start_y_i +=src_walk_vy_i;
src_space_cur_pos_x_i = src_space_row_start_x_i;
src_space_cur_pos_y_i = src_space_row_start_y_i;
src_space_cur_pos_x = src_space_cur_pos_x_i >> fraction_bits;
src_space_cur_pos_y = src_space_cur_pos_y_i >> fraction_bits;
} /* end for y */
if (hardness < 1.0)
{
GimpTempBuf *blur_src;
GeglBuffer *src_buffer;
GeglBuffer *dest_buffer;
gint kernel_size =
gimp_brush_transform_blur_kernel_size (gimp_temp_buf_get_height (result),
gimp_temp_buf_get_width (result),
hardness);
gint kernel_len = kernel_size * kernel_size;
gfloat blur_kernel[kernel_len];
gimp_brush_transform_fill_blur_kernel (blur_kernel, kernel_len);
blur_src = gimp_temp_buf_copy (result);
src_buffer = gimp_temp_buf_create_buffer (blur_src);
dest_buffer = gimp_temp_buf_create_buffer (result);
gimp_temp_buf_unref (blur_src);
gimp_gegl_convolve (src_buffer,
GEGL_RECTANGLE (0, 0,
gimp_temp_buf_get_width (blur_src),
gimp_temp_buf_get_height (blur_src)),
dest_buffer,
GEGL_RECTANGLE (0, 0,
gimp_temp_buf_get_width (result),
gimp_temp_buf_get_height (result)),
blur_kernel, kernel_size,
gimp_brush_transform_array_sum (blur_kernel,
kernel_len),
GIMP_NORMAL_CONVOL, FALSE);
g_object_unref (src_buffer);
g_object_unref (dest_buffer);
}
return result;
}
/*
* Transforms the brush pixmap with bilinear interpolation.
*
* The algorithm used is exactly the same as for the brush mask
* (gimp_brush_real_transform_mask) except it accounts for 3 color channels
* instead of 1 grayscale channel.
*
* Rather than calculating the inverse transform for each point in the
* transformed image, this algorithm uses the inverse transformed
* corner points of the destination image to work out the starting
* position in the source image and the U and V deltas in the source
* image space. It then uses a scan-line approach, looping through
* rows and colummns in the transformed (destination) image while
* walking along the corresponding rows and columns (named U and V) in
* the source image.
*
* The horizontal in destination space (transform result) is reverse
* transformed into source image space to get U. The vertical in
* destination space (transform result) is reverse transformed into
* source image space to get V.
*
* The strength of this particular algorithm is that calculation work
* should depend more upon the final transformed brush size rather
* than the input brush size.
*
* There are no floating point calculations in the inner loop for speed.
*
* Some variables end with the suffix _i to indicate they have been
* premultiplied by int_multiple
*/
GimpTempBuf *
gimp_brush_real_transform_pixmap (GimpBrush *brush,
gdouble scale,
gdouble aspect_ratio,
gdouble angle,
gdouble hardness)
{
GimpTempBuf *result;
GimpTempBuf *source;
guchar *dest;
const guchar *src;
GimpMatrix3 matrix;
gint src_width;
gint src_height;
gint src_width_minus_one;
gint src_height_minus_one;
gint dest_width;
gint dest_height;
gint x, y;
gdouble blx, brx, tlx, trx;
gdouble bly, bry, tly, try;
gdouble src_tl_to_tr_delta_x;
gdouble src_tl_to_tr_delta_y;
gdouble src_tl_to_bl_delta_x;
gdouble src_tl_to_bl_delta_y;
gint src_walk_ux_i;
gint src_walk_uy_i;
gint src_walk_vx_i;
gint src_walk_vy_i;
gint src_space_cur_pos_x;
gint src_space_cur_pos_y;
gint src_space_cur_pos_x_i;
gint src_space_cur_pos_y_i;
gint src_space_row_start_x_i;
gint src_space_row_start_y_i;
const guchar *src_walker;
const guchar *pixel_next;
const guchar *pixel_below;
const guchar *pixel_below_next;
gint opposite_x, distance_from_true_x;
gint opposite_y, distance_from_true_y;
/*
* tl, tr etc are used because it is easier to visualize top left,
* top right etc corners of the forward transformed source image
* rectangle.
*/
const gint fraction_bits = 12;
const gint int_multiple = pow(2,fraction_bits);
/* In inner loop's bilinear calculation, two numbers that were each
* previously multiplied by int_multiple are multiplied together.
* To get back the right result, the multiplication result must be
* divided *twice* by 2^fraction_bits, equivalent to bit shift right
* by 2 * fraction_bits
*/
const gint recovery_bits = 2 * fraction_bits;
/*
* example: suppose fraction_bits = 9
* a 9-bit mask looks like this: 0001 1111 1111
* and is given by: 2^fraction_bits - 1
* demonstration:
* 2^0 = 0000 0000 0001
* 2^1 = 0000 0000 0010
* :
* 2^8 = 0001 0000 0000
* 2^9 = 0010 0000 0000
* 2^9 - 1 = 0001 1111 1111
*/
const guint fraction_bitmask = pow(2, fraction_bits)- 1 ;
source = brush->pixmap;
src_width = gimp_temp_buf_get_width (source);
src_height = gimp_temp_buf_get_height (source);
gimp_brush_transform_matrix (src_width, src_height,
scale, aspect_ratio, angle, &matrix);
if (gimp_matrix3_is_identity (&matrix))
return gimp_temp_buf_copy (source);
src_width_minus_one = src_width - 1;
src_height_minus_one = src_height - 1;
gimp_brush_transform_bounding_box (source, &matrix,
&x, &y, &dest_width, &dest_height);
gimp_matrix3_translate (&matrix, -x, -y);
gimp_matrix3_invert (&matrix);
result = gimp_temp_buf_new (dest_width, dest_height,
gimp_temp_buf_get_format (brush->pixmap));
dest = gimp_temp_buf_get_data (result);
src = gimp_temp_buf_get_data (source);
gimp_matrix3_transform_point (&matrix, 0, 0, &tlx, &tly);
gimp_matrix3_transform_point (&matrix, dest_width, 0, &trx, &try);
gimp_matrix3_transform_point (&matrix, 0, dest_height, &blx, &bly);
gimp_matrix3_transform_point (&matrix, dest_width, dest_height, &brx, &bry);
/* in image space, calc U (what was horizontal originally)
* note: double precision
*/
src_tl_to_tr_delta_x = trx - tlx;
src_tl_to_tr_delta_y = try - tly;
/* in image space, calc V (what was vertical originally)
* note: double precision
*/
src_tl_to_bl_delta_x = blx - tlx;
src_tl_to_bl_delta_y = bly - tly;
/* speed optimized, note conversion to int precision */
src_walk_ux_i = (gint) ((src_tl_to_tr_delta_x / dest_width)* int_multiple);
src_walk_uy_i = (gint) ((src_tl_to_tr_delta_y / dest_width)* int_multiple);
src_walk_vx_i = (gint) ((src_tl_to_bl_delta_x / dest_height)* int_multiple);
src_walk_vy_i = (gint) ((src_tl_to_bl_delta_y / dest_height)* int_multiple);
/* initialize current position in source space to the start position (tl)
* speed optimized, note conversion to int precision
*/
src_space_cur_pos_x_i = (gint) (tlx* int_multiple);
src_space_cur_pos_y_i = (gint) (tly* int_multiple);
src_space_cur_pos_x = (gint) (src_space_cur_pos_x_i >> fraction_bits);
src_space_cur_pos_y = (gint) (src_space_cur_pos_y_i >> fraction_bits);
src_space_row_start_x_i = (gint) (tlx* int_multiple);
src_space_row_start_y_i = (gint) (tly* int_multiple);
for (y = 0; y < dest_height; y++)
{
for (x = 0; x < dest_width; x++)
{
if (src_space_cur_pos_x > src_width_minus_one ||
src_space_cur_pos_x < 0 ||
src_space_cur_pos_y > src_height_minus_one ||
src_space_cur_pos_y < 0)
/* no corresponding pixel in source space */
{
dest[0] = 0;
dest[1] = 0;
dest[2] = 0;
}
else /* reverse transformed point hits source pixel */
{
src_walker = src
+ 3 * (
src_space_cur_pos_y * src_width
+ src_space_cur_pos_x);
/* bottom right corner
* no pixel below, reuse current pixel instead
* no next pixel to the right so reuse current pixel instead
*/
if (src_space_cur_pos_y == src_height_minus_one &&
src_space_cur_pos_x == src_width_minus_one )
{
pixel_next = src_walker;
pixel_below = src_walker;
pixel_below_next = src_walker;
}
/* bottom edge pixel row, except rightmost corner
* no pixel below, reuse current pixel instead */
else if (src_space_cur_pos_y == src_height_minus_one)
{
pixel_next = src_walker + 3;
pixel_below = src_walker;
pixel_below_next = src_walker + 3;
}
/* right edge pixel column, except bottom corner
* no next pixel to the right so reuse current pixel instead */
else if (src_space_cur_pos_x == src_width_minus_one)
{
pixel_next = src_walker;
pixel_below = src_walker + src_width * 3;
pixel_below_next = pixel_below;
}
/* neither on bottom edge nor on right edge */
else
{
pixel_next = src_walker + 3;
pixel_below = src_walker + src_width * 3;
pixel_below_next = pixel_below + 3;
}
distance_from_true_x = src_space_cur_pos_x_i & fraction_bitmask;
distance_from_true_y = src_space_cur_pos_y_i & fraction_bitmask;
opposite_x = int_multiple - distance_from_true_x;
opposite_y = int_multiple - distance_from_true_y;
dest[0] = ((src_walker[0] * opposite_x +
pixel_next[0] * distance_from_true_x) * opposite_y +
(pixel_below[0] * opposite_x +
pixel_below_next[0] *distance_from_true_x) * distance_from_true_y
) >> recovery_bits;
dest[1] = ((src_walker[1] * opposite_x +
pixel_next[1] * distance_from_true_x) * opposite_y +
(pixel_below[1] * opposite_x +
pixel_below_next[1] *distance_from_true_x) * distance_from_true_y
) >> recovery_bits;
dest[2] = ((src_walker[2] * opposite_x +
pixel_next[2] * distance_from_true_x) * opposite_y +
(pixel_below[2] * opposite_x +
pixel_below_next[2] *distance_from_true_x) * distance_from_true_y
) >> recovery_bits;
}
src_space_cur_pos_x_i += src_walk_ux_i;
src_space_cur_pos_y_i += src_walk_uy_i;
src_space_cur_pos_x = src_space_cur_pos_x_i >> fraction_bits;
src_space_cur_pos_y = src_space_cur_pos_y_i >> fraction_bits;
dest += 3;
} /* end for x */
src_space_row_start_x_i +=src_walk_vx_i;
src_space_row_start_y_i +=src_walk_vy_i;
src_space_cur_pos_x_i = src_space_row_start_x_i;
src_space_cur_pos_y_i = src_space_row_start_y_i;
src_space_cur_pos_x = src_space_cur_pos_x_i >> fraction_bits;
src_space_cur_pos_y = src_space_cur_pos_y_i >> fraction_bits;
} /* end for y */
if (hardness < 1.0)
{
GimpTempBuf *blur_src;
GeglBuffer *src_buffer;
GeglBuffer *dest_buffer;
gint kernel_size =
gimp_brush_transform_blur_kernel_size (gimp_temp_buf_get_height (result),
gimp_temp_buf_get_width (result),
hardness);
gint kernel_len = kernel_size * kernel_size;
gfloat blur_kernel[kernel_len];
gimp_brush_transform_fill_blur_kernel (blur_kernel, kernel_len);
blur_src = gimp_temp_buf_copy (result);
src_buffer = gimp_temp_buf_create_buffer (blur_src);
dest_buffer = gimp_temp_buf_create_buffer (result);
gimp_temp_buf_unref (blur_src);
gimp_gegl_convolve (src_buffer,
GEGL_RECTANGLE (0, 0,
gimp_temp_buf_get_width (blur_src),
gimp_temp_buf_get_height (blur_src)),
dest_buffer,
GEGL_RECTANGLE (0, 0,
gimp_temp_buf_get_width (result),
gimp_temp_buf_get_height (result)),
blur_kernel, kernel_size,
gimp_brush_transform_array_sum (blur_kernel,
kernel_len),
GIMP_NORMAL_CONVOL, FALSE);
g_object_unref (src_buffer);
g_object_unref (dest_buffer);
}
return result;
}
void
gimp_brush_transform_matrix (gdouble width,
gdouble height,
gdouble scale,
gdouble aspect_ratio,
gdouble angle,
GimpMatrix3 *matrix)
{
const gdouble center_x = width / 2;
const gdouble center_y = height / 2;
gdouble scale_x = scale;
gdouble scale_y = scale;
if (aspect_ratio < 0.0)
{
scale_x = scale * (1.0 - (fabs (aspect_ratio) / 20.0));
scale_y = scale;
}
else if (aspect_ratio > 0.0)
{
scale_x = scale;
scale_y = scale * (1.0 - (aspect_ratio / 20.0));
}
gimp_matrix3_identity (matrix);
gimp_matrix3_scale (matrix, scale_x, scale_y);
gimp_matrix3_translate (matrix, - center_x * scale_x, - center_y * scale_y);
gimp_matrix3_rotate (matrix, -2 * G_PI * angle);
gimp_matrix3_translate (matrix, center_x * scale_x, center_y * scale_y);
}
/* private functions */
static void
gimp_brush_transform_bounding_box (GimpTempBuf *brush,
const GimpMatrix3 *matrix,
gint *x,
gint *y,
gint *width,
gint *height)
{
const gdouble w = gimp_temp_buf_get_width (brush);
const gdouble h = gimp_temp_buf_get_height (brush);
gdouble x1, x2, x3, x4;
gdouble y1, y2, y3, y4;
gdouble temp_x;
gdouble temp_y;
gimp_matrix3_transform_point (matrix, 0, 0, &x1, &y1);
gimp_matrix3_transform_point (matrix, w, 0, &x2, &y2);
gimp_matrix3_transform_point (matrix, 0, h, &x3, &y3);
gimp_matrix3_transform_point (matrix, w, h, &x4, &y4);
temp_x = MIN (MIN (x1, x2), MIN (x3, x4));
temp_y = MIN (MIN (y1, y2), MIN (y3, y4));
*width = (gint) ceil (MAX (MAX (x1, x2), MAX (x3, x4)) - temp_x);
*height = (gint) ceil (MAX (MAX (y1, y2), MAX (y3, y4)) - temp_y);
*x = floor (temp_x);
*y = floor (temp_y);
/* Transform size can not be less than 1 px */
*width = MAX (1, *width);
*height = MAX (1, *height);
}
static gdouble
gimp_brush_transform_array_sum (gfloat *arr,
gint len)
{
gfloat total = 0;
gint i;
for (i = 0; i < len; i++)
{
total += arr [i];
}
return total;
}
static void
gimp_brush_transform_fill_blur_kernel (gfloat *arr,
gint len)
{
gint half_point = ((gint) len / 2) + 1;
gint i;
for (i = 0; i < len; i++)
{
if (i < half_point)
arr [i] = half_point - i;
else
arr [i] = i - half_point;
}
}
static gint
gimp_brush_transform_blur_kernel_size (gint height,
gint width,
gdouble hardness)
{
gint kernel_size = (MIN (MAX_BLUR_KERNEL,
MIN (width, height)) *
((MIN (width, height) * (1.0 - hardness)) /
MIN (width, height)));
/* Kernel size must be odd */
if (kernel_size % 2 == 0)
kernel_size++;
return kernel_size;
}