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gimp/app/core/gimpbrush-transform.c

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/* 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 <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <glib-object.h>
#include "core-types.h"
#include "libgimpmath/gimpmath.h"
#include "gimpbrush.h"
#include "gimpbrush-transform.h"
#include "base/temp-buf.h"
/* local function prototypes */
static void gimp_brush_transform_matrix (GimpBrush *brush,
gdouble scale_x,
gdouble scale_y,
gdouble angle,
GimpMatrix3 *matrix);
static void gimp_brush_transform_bounding_box (GimpBrush *brush,
const GimpMatrix3 *matrix,
gint *x,
gint *y,
gint *width,
gint *height);
/* 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;
if (aspect_ratio < 1.0)
gimp_brush_transform_matrix (brush,
scale * aspect_ratio, scale, angle, &matrix);
else
gimp_brush_transform_matrix (brush,
scale, scale / aspect_ratio, angle, &matrix);
gimp_brush_transform_bounding_box (brush, &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
*/
TempBuf *
gimp_brush_real_transform_mask (GimpBrush *brush,
gdouble scale,
gdouble aspect_ratio,
gdouble angle)
{
TempBuf *result;
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 ;
if (aspect_ratio < 1.0)
gimp_brush_transform_matrix (brush,
scale * aspect_ratio, scale, angle, &matrix);
else
gimp_brush_transform_matrix (brush,
scale, scale / aspect_ratio, angle, &matrix);
if (gimp_matrix3_is_identity (&matrix))
return temp_buf_copy (brush->mask, NULL);
src_width = brush->mask->width;
src_height = brush->mask->height;
src_width_minus_one = src_width - 1;
src_height_minus_one = src_height - 1;
gimp_brush_transform_bounding_box (brush, &matrix,
&x, &y, &dest_width, &dest_height);
gimp_matrix3_translate (&matrix, -x, -y);
gimp_matrix3_invert (&matrix);
result = temp_buf_new (dest_width, dest_height, 1, 0, 0, NULL);
dest = temp_buf_get_data (result);
src = temp_buf_get_data (brush->mask);
/* 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 */
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 greyscale 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
*/
TempBuf *
gimp_brush_real_transform_pixmap (GimpBrush *brush,
gdouble scale,
gdouble aspect_ratio,
gdouble angle)
{
TempBuf *result;
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 ;
if (aspect_ratio < 1.0)
gimp_brush_transform_matrix (brush,
scale * aspect_ratio, scale, angle, &matrix);
else
gimp_brush_transform_matrix (brush,
scale, scale / aspect_ratio, angle, &matrix);
if (gimp_matrix3_is_identity (&matrix))
return temp_buf_copy (brush->pixmap, NULL);
src_width = brush->pixmap->width;
src_height = brush->pixmap->height;
src_width_minus_one = src_width - 1;
src_height_minus_one = src_height - 1;
gimp_brush_transform_bounding_box (brush, &matrix,
&x, &y, &dest_width, &dest_height);
gimp_matrix3_translate (&matrix, -x, -y);
gimp_matrix3_invert (&matrix);
result = temp_buf_new (dest_width, dest_height, 3, 0, 0, NULL);
dest = temp_buf_get_data (result);
src = temp_buf_get_data (brush->pixmap);
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 */
return result;
}
/* private functions */
static void
gimp_brush_transform_matrix (GimpBrush *brush,
gdouble scale_x,
gdouble scale_y,
gdouble angle,
GimpMatrix3 *matrix)
{
const gdouble center_x = brush->mask->width / 2;
const gdouble center_y = brush->mask->height / 2;
gimp_matrix3_identity (matrix);
gimp_matrix3_translate (matrix, - center_x, - center_y);
gimp_matrix3_rotate (matrix, -2 * G_PI * angle);
gimp_matrix3_translate (matrix, center_x, center_y);
gimp_matrix3_scale (matrix, scale_x, scale_y);
}
static void
gimp_brush_transform_bounding_box (GimpBrush *brush,
const GimpMatrix3 *matrix,
gint *x,
gint *y,
gint *width,
gint *height)
{
const gdouble w = brush->mask->width;
const gdouble h = brush->mask->height;
gdouble x1, x2, x3, x4;
gdouble y1, y2, y3, y4;
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);
*x = floor (MIN (MIN (x1, x2), MIN (x3, x4)));
*y = floor (MIN (MIN (y1, y2), MIN (y3, y4)));
*width = (gint) (ceil (MAX (MAX (x1, x2), MAX (x3, x4))) - *x);
*height = (gint) (ceil (MAX (MAX (y1, y2), MAX (y3, y4))) - *y);
}
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