gimp/plug-ins/common/noisify.c

852 lines
22 KiB
C

/*
* This is a plugin for the GIMP.
*
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
* Copyright (C) 1996 Torsten Martinsen
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* $Id$
*/
/*
* This filter adds random noise to an image.
* The amount of noise can be set individually for each RGB channel.
* This filter does not operate on indexed images.
*
* May 2000 tim copperfield [timecop@japan.co.jp]
* Added dynamic preview.
*
* alt@gimp.org. Fixed previews so they handle alpha channels correctly.
*/
#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#ifdef __GNUC__
#warning GTK_DISABLE_DEPRECATED
#endif
#undef GTK_DISABLE_DEPRECATED
#include <gtk/gtk.h>
#include <libgimp/gimp.h>
#include <libgimp/gimpui.h>
#include "libgimp/stdplugins-intl.h"
#define SCALE_WIDTH 125
#define TILE_CACHE_SIZE 16
#define PREVIEW_SIZE 128
typedef struct
{
gint independent;
gdouble noise[4]; /* per channel */
} NoisifyVals;
typedef struct
{
gint channels;
GtkObject *channel_adj[4];
gint run;
} NoisifyInterface;
/* Declare local functions.
*/
static void query (void);
static void run (gchar *name,
gint nparams,
GimpParam *param,
gint *nreturn_vals,
GimpParam **return_vals);
static void noisify (GimpDrawable *drawable,
gboolean preview_mode);
static gdouble gauss (void);
static void fill_preview (GtkWidget *preview_widget,
GimpDrawable *drawable);
static GtkWidget *preview_widget (GimpDrawable *drawable);
static gint noisify_dialog (GimpDrawable *drawable,
gint channels);
static void noisify_ok_callback (GtkWidget *widget,
gpointer data);
static void noisify_double_adjustment_update (GtkAdjustment *adjustment,
gpointer data);
GimpPlugInInfo PLUG_IN_INFO =
{
NULL, /* init_proc */
NULL, /* quit_proc */
query, /* query_proc */
run, /* run_proc */
};
static NoisifyVals nvals =
{
TRUE,
{ 0.20, 0.20, 0.20, 0.20 }
};
static NoisifyInterface noise_int =
{
0,
{ NULL, NULL, NULL, NULL },
FALSE /* run */
};
static GtkWidget *preview;
static guchar *preview_cache;
static gint preview_cache_rowstride;
static gint preview_cache_bpp;
MAIN ()
static void
query (void)
{
static GimpParamDef args[] =
{
{ GIMP_PDB_INT32, "run_mode", "Interactive, non-interactive" },
{ GIMP_PDB_IMAGE, "image", "Input image (unused)" },
{ GIMP_PDB_DRAWABLE, "drawable", "Input drawable" },
{ GIMP_PDB_INT32, "independent", "Noise in channels independent" },
{ GIMP_PDB_FLOAT, "noise_1", "Noise in the first channel (red, gray)" },
{ GIMP_PDB_FLOAT, "noise_2", "Noise in the second channel (green, gray_alpha)" },
{ GIMP_PDB_FLOAT, "noise_3", "Noise in the third channel (blue)" },
{ GIMP_PDB_FLOAT, "noise_4", "Noise in the fourth channel (alpha)" }
};
gimp_install_procedure ("plug_in_noisify",
"Adds random noise to a drawable's channels",
"More here later",
"Torsten Martinsen",
"Torsten Martinsen",
"May 2000",
N_("<Image>/Filters/Noise/Noisify..."),
"RGB*, GRAY*",
GIMP_PLUGIN,
G_N_ELEMENTS (args), 0,
args, NULL);
}
static void
run (gchar *name,
gint nparams,
GimpParam *param,
gint *nreturn_vals,
GimpParam **return_vals)
{
static GimpParam values[1];
GimpDrawable *drawable;
GimpRunMode run_mode;
GimpPDBStatusType status = GIMP_PDB_SUCCESS;
run_mode = param[0].data.d_int32;
*nreturn_vals = 1;
*return_vals = values;
values[0].type = GIMP_PDB_STATUS;
values[0].data.d_status = status;
/* Get the specified drawable */
drawable = gimp_drawable_get (param[2].data.d_drawable);
switch (run_mode)
{
case GIMP_RUN_INTERACTIVE:
INIT_I18N_UI();
/* Possibly retrieve data */
gimp_get_data ("plug_in_noisify", &nvals);
/* First acquire information with a dialog */
if (! noisify_dialog (drawable, drawable->bpp))
{
gimp_drawable_detach (drawable);
return;
}
break;
case GIMP_RUN_NONINTERACTIVE:
INIT_I18N();
/* Make sure all the arguments are there! */
if (nparams != 8)
{
status = GIMP_PDB_CALLING_ERROR;
}
else
{
nvals.independent = param[3].data.d_int32 ? TRUE : FALSE;
nvals.noise[0] = param[4].data.d_float;
nvals.noise[1] = param[5].data.d_float;
nvals.noise[2] = param[6].data.d_float;
nvals.noise[3] = param[7].data.d_float;
}
break;
case GIMP_RUN_WITH_LAST_VALS:
INIT_I18N();
/* Possibly retrieve data */
gimp_get_data ("plug_in_noisify", &nvals);
break;
default:
break;
}
/* Make sure that the drawable is gray or RGB color */
if (gimp_drawable_is_rgb (drawable->drawable_id) ||
gimp_drawable_is_gray (drawable->drawable_id))
{
gimp_progress_init (_("Adding Noise..."));
gimp_tile_cache_ntiles (TILE_CACHE_SIZE);
/* seed the random number generator */
srand (time (NULL));
/* compute the luminosity which exceeds the luminosity threshold */
noisify (drawable, FALSE);
if (run_mode != GIMP_RUN_NONINTERACTIVE)
gimp_displays_flush ();
/* Store data */
if (run_mode == GIMP_RUN_INTERACTIVE) {
gimp_set_data ("plug_in_noisify", &nvals, sizeof (NoisifyVals));
g_free(preview_cache);
}
}
else
{
/* gimp_message ("blur: cannot operate on indexed color images"); ??? BLUR ??? */
status = GIMP_PDB_EXECUTION_ERROR;
}
values[0].data.d_status = status;
gimp_drawable_detach (drawable);
}
static void
preview_do_row(gint row,
gint width,
guchar *even,
guchar *odd,
guchar *src)
{
gint x;
guchar *p0 = even;
guchar *p1 = odd;
gdouble r, g, b, a;
gdouble c0, c1;
for (x = 0; x < width; x++)
{
if (preview_cache_bpp == 4)
{
r = ((gdouble)src[x*4+0]) / 255.0;
g = ((gdouble)src[x*4+1]) / 255.0;
b = ((gdouble)src[x*4+2]) / 255.0;
a = ((gdouble)src[x*4+3]) / 255.0;
}
else if (preview_cache_bpp == 3)
{
r = ((gdouble)src[x*3+0]) / 255.0;
g = ((gdouble)src[x*3+1]) / 255.0;
b = ((gdouble)src[x*3+2]) / 255.0;
a = 1.0;
}
else
{
r = ((gdouble)src[x*preview_cache_bpp+0]) / 255.0;
g = b = r;
if (preview_cache_bpp == 2)
a = ((gdouble)src[x*preview_cache_bpp+1]) / 255.0;
else
a = 1.0;
}
if ((x / GIMP_CHECK_SIZE) & 1)
{
c0 = GIMP_CHECK_LIGHT;
c1 = GIMP_CHECK_DARK;
}
else
{
c0 = GIMP_CHECK_DARK;
c1 = GIMP_CHECK_LIGHT;
}
*p0++ = (c0 + (r - c0) * a) * 255.0;
*p0++ = (c0 + (g - c0) * a) * 255.0;
*p0++ = (c0 + (b - c0) * a) * 255.0;
*p1++ = (c1 + (r - c1) * a) * 255.0;
*p1++ = (c1 + (g - c1) * a) * 255.0;
*p1++ = (c1 + (b - c1) * a) * 255.0;
} /* for */
if ((row / GIMP_CHECK_SIZE) & 1)
{
gtk_preview_draw_row (GTK_PREVIEW (preview), (guchar *)odd, 0, row, width);
}
else
{
gtk_preview_draw_row (GTK_PREVIEW (preview), (guchar *)even, 0, row, width);
}
}
static void
noisify (GimpDrawable *drawable,
gboolean preview_mode)
{
GimpPixelRgn src_rgn, dest_rgn;
guchar *src_row, *dest_row;
guchar *src, *dest, *dest_data;
gint row, col, b;
gint x1, y1, x2, y2, p, bpp = 3;
gint noise;
gint progress = 0, max_progress = 0;
gpointer pr;
gint row_stride = 0;
guchar *odd = NULL;
guchar *even = NULL;
/* initialize */
noise = 0;
if (preview_mode)
{
x1 = y1 = 0;
x2 = GTK_PREVIEW (preview)->buffer_width;
y2 = GTK_PREVIEW (preview)->buffer_height;
bpp = preview_cache_bpp;
row_stride = preview_cache_rowstride;
even = g_malloc (x2 * 3);
odd = g_malloc (x2 * 3);
}
else
{
gimp_drawable_mask_bounds (drawable->drawable_id, &x1, &y1, &x2, &y2);
gimp_pixel_rgn_init (&src_rgn, drawable,
x1, y1, (x2 - x1), (y2 - y1), FALSE, FALSE);
gimp_pixel_rgn_init (&dest_rgn, drawable,
x1, y1, (x2 - x1), (y2 - y1), TRUE, TRUE);
/* Initialize progress */
progress = 0;
max_progress = (x2 - x1) * (y2 - y1);
}
if (preview_mode)
{
dest_data = g_malloc (row_stride * y2);
for (row = 0; row < y2; row++)
{
src = preview_cache + row * row_stride;
dest = dest_data + row * row_stride;
for (col = 0; col < x2; col++)
{
if (nvals.independent == FALSE)
noise = (gint) (nvals.noise[0] * gauss() * 127);
for (b = 0; b < bpp; b++)
{
if (nvals.independent == TRUE)
noise = (gint) (nvals.noise[b] * gauss() * 127);
if (nvals.noise[b] > 0.0)
{
p = src[b] + noise;
if (p < 0)
p = 0;
else if (p > 255)
p = 255;
dest[b] = p;
}
else
dest[b] = src[b];
}
src += bpp;
dest += bpp;
}
}
for (row = 0; row < y2; row++)
{
preview_do_row(row,x2,even,odd,dest_data + row * row_stride);
}
gtk_widget_queue_draw (preview);
g_free(even);
g_free(odd);
}
else
{
for (pr = gimp_pixel_rgns_register (2, &src_rgn, &dest_rgn);
pr != NULL;
pr = gimp_pixel_rgns_process (pr))
{
src_row = src_rgn.data;
dest_row = dest_rgn.data;
for (row = 0; row < src_rgn.h; row++)
{
src = src_row;
dest = dest_row;
for (col = 0; col < src_rgn.w; col++)
{
if (nvals.independent == FALSE)
noise = (gint) (nvals.noise[0] * gauss() * 127);
for (b = 0; b < src_rgn.bpp; b++)
{
if (nvals.independent == TRUE)
noise = (gint) (nvals.noise[b] * gauss() * 127);
if (nvals.noise[b] > 0.0)
{
p = src[b] + noise;
if (p < 0)
p = 0;
else if (p > 255)
p = 255;
dest[b] = p;
}
else
dest[b] = src[b];
}
src += src_rgn.bpp;
dest += dest_rgn.bpp;
}
src_row += src_rgn.rowstride;
dest_row += dest_rgn.rowstride;
}
/* Update progress */
progress += src_rgn.w * src_rgn.h;
gimp_progress_update ((double) progress / (double) max_progress);
}
/* update the blurred region */
gimp_drawable_flush (drawable);
gimp_drawable_merge_shadow (drawable->drawable_id, TRUE);
gimp_drawable_update (drawable->drawable_id, x1, y1, (x2 - x1), (y2 - y1));
} /* endif normal mode */
}
static gint
noisify_dialog (GimpDrawable *drawable,
gint channels)
{
GtkWidget *dlg;
GtkWidget *main_vbox;
GtkWidget *abox;
GtkWidget *toggle;
GtkWidget *frame;
GtkWidget *table;
GtkObject *adj;
gchar *buffer;
gint i;
gimp_ui_init ("noisify", FALSE);
dlg = gimp_dialog_new (_("Noisify"), "noisify",
gimp_standard_help_func, "filters/noisify.html",
GTK_WIN_POS_MOUSE,
FALSE, TRUE, FALSE,
GTK_STOCK_CANCEL, gtk_widget_destroy,
NULL, 1, NULL, FALSE, TRUE,
GTK_STOCK_OK, noisify_ok_callback,
NULL, NULL, NULL, TRUE, FALSE,
NULL);
g_signal_connect (G_OBJECT (dlg), "destroy",
G_CALLBACK (gtk_main_quit),
NULL);
main_vbox = gtk_vbox_new (FALSE, 2);
gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 0);
gtk_box_pack_start (GTK_BOX (GTK_DIALOG (dlg)->vbox), main_vbox, TRUE, TRUE, 0);
gtk_widget_show (main_vbox);
/* preview */
frame = gtk_frame_new (_("Preview"));
gtk_container_set_border_width (GTK_CONTAINER (frame), 6);
gtk_box_pack_start (GTK_BOX (main_vbox), frame, FALSE, FALSE, 0);
gtk_widget_show (frame);
abox = gtk_alignment_new (0.5, 0.5, 0.0, 0.0);
gtk_container_set_border_width (GTK_CONTAINER (abox), 4);
gtk_container_add (GTK_CONTAINER (frame), abox);
gtk_widget_show (abox);
frame = gtk_frame_new (NULL);
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
gtk_container_add (GTK_CONTAINER (abox), frame);
gtk_widget_show (frame);
preview = preview_widget (drawable);
gtk_container_add (GTK_CONTAINER (frame), preview);
noisify (drawable, TRUE); /* preview noisify */
gtk_widget_show (preview);
/* parameter settings */
frame = gtk_frame_new (_("Parameter Settings"));
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_ETCHED_IN);
gtk_container_set_border_width (GTK_CONTAINER (frame), 6);
gtk_box_pack_start (GTK_BOX (main_vbox), frame, TRUE, TRUE, 0);
table = gtk_table_new (channels + 1, 3, FALSE);
gtk_table_set_col_spacings (GTK_TABLE (table), 4);
gtk_table_set_row_spacings (GTK_TABLE (table), 2);
gtk_table_set_row_spacing (GTK_TABLE (table), 0, 4);
gtk_container_set_border_width (GTK_CONTAINER (table), 4);
gtk_container_add (GTK_CONTAINER (frame), table);
toggle = gtk_check_button_new_with_mnemonic (_("_Independent"));
gtk_table_attach (GTK_TABLE (table), toggle, 0, 3, 0, 1, GTK_FILL, 0, 0, 0);
gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle), nvals.independent);
gtk_widget_show (toggle);
g_signal_connect (G_OBJECT (toggle), "toggled",
G_CALLBACK (gimp_toggle_button_update),
&nvals.independent);
noise_int.channels = channels;
if (channels == 1)
{
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 1,
_("_Gray:"), SCALE_WIDTH, 0,
nvals.noise[0], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[0]);
noise_int.channel_adj[0] = adj;
}
else if (channels == 2)
{
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 1,
_("_Gray:"), SCALE_WIDTH, 0,
nvals.noise[0], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[0]);
noise_int.channel_adj[0] = adj;
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 2,
_("_Alpha:"), SCALE_WIDTH, 0,
nvals.noise[1], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[1]);
noise_int.channel_adj[1] = adj;
}
else if (channels == 3)
{
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 1,
_("_Red:"), SCALE_WIDTH, 0,
nvals.noise[0], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[0]);
noise_int.channel_adj[0] = adj;
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 2,
_("_Green:"), SCALE_WIDTH, 0,
nvals.noise[1], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[1]);
noise_int.channel_adj[1] = adj;
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 3,
_("_Blue:"), SCALE_WIDTH, 0,
nvals.noise[2], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[2]);
noise_int.channel_adj[2] = adj;
}
else if (channels == 4)
{
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 1,
_("_Red:"), SCALE_WIDTH, 0,
nvals.noise[0], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[0]);
noise_int.channel_adj[0] = adj;
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 2,
_("_Green:"), SCALE_WIDTH, 0,
nvals.noise[1], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[1]);
noise_int.channel_adj[1] = adj;
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 3,
_("_Blue:"), SCALE_WIDTH, 0,
nvals.noise[2], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[2]);
noise_int.channel_adj[2] = adj;
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, 4,
_("_Alpha:"), SCALE_WIDTH, 0,
nvals.noise[3], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[3]);
noise_int.channel_adj[3] = adj;
}
else
{
for (i = 0; i < channels; i++)
{
buffer = g_strdup_printf (_("Channel #%d:"), i);
adj = gimp_scale_entry_new (GTK_TABLE (table), 0, i + 1,
buffer, SCALE_WIDTH, 0,
nvals.noise[i], 0.0, 1.0, 0.01, 0.1, 2,
TRUE, 0, 0,
NULL, NULL);
g_object_set_data (G_OBJECT (adj), "drawable", drawable);
g_signal_connect (G_OBJECT (adj), "value_changed",
G_CALLBACK (noisify_double_adjustment_update),
&nvals.noise[i]);
noise_int.channel_adj[i] = adj;
g_free (buffer);
}
}
gtk_widget_show (frame);
gtk_widget_show (table);
gtk_widget_show (dlg);
gtk_main ();
gdk_flush ();
return noise_int.run;
}
/*
* Return a Gaussian (aka normal) random variable.
*
* Adapted from ppmforge.c, which is part of PBMPLUS.
* The algorithm comes from:
* 'The Science Of Fractal Images'. Peitgen, H.-O., and Saupe, D. eds.
* Springer Verlag, New York, 1988.
*/
static gdouble
gauss (void)
{
gint i;
gdouble sum = 0.0;
for (i = 0; i < 4; i++)
sum += rand () & 0x7FFF;
return sum * 5.28596089837e-5 - 3.46410161514;
}
static void
noisify_ok_callback (GtkWidget *widget,
gpointer data)
{
noise_int.run = TRUE;
gtk_widget_destroy (GTK_WIDGET (data));
}
static void
noisify_double_adjustment_update (GtkAdjustment *adjustment,
gpointer data)
{
GimpDrawable *drawable;
gimp_double_adjustment_update (adjustment, data);
drawable = g_object_get_data (G_OBJECT (adjustment), "drawable");
noisify (drawable, TRUE);
if (! nvals.independent)
{
gint i;
for (i = 0; i < noise_int.channels; i++)
if (adjustment != GTK_ADJUSTMENT (noise_int.channel_adj[i]))
gtk_adjustment_set_value (GTK_ADJUSTMENT (noise_int.channel_adj[i]),
adjustment->value);
}
}
static GtkWidget *
preview_widget (GimpDrawable *drawable)
{
gint size;
preview = gtk_preview_new (GTK_PREVIEW_COLOR);
fill_preview (preview, drawable);
size = GTK_PREVIEW (preview)->rowstride * GTK_PREVIEW (preview)->buffer_height;
return preview;
}
static void
fill_preview (GtkWidget *widget,
GimpDrawable *drawable)
{
GimpPixelRgn srcPR;
gint width;
gint height;
gint x1, x2, y1, y2;
gint bpp;
gint y;
guchar *src;
guchar *even, *odd;
gimp_drawable_mask_bounds (drawable->drawable_id, &x1, &y1, &x2, &y2);
if (x2 - x1 > PREVIEW_SIZE)
x2 = x1 + PREVIEW_SIZE;
if (y2 - y1 > PREVIEW_SIZE)
y2 = y1 + PREVIEW_SIZE;
width = x2 - x1;
height = y2 - y1;
bpp = gimp_drawable_bpp (drawable->drawable_id);
if (width < 1 || height < 1)
return;
gtk_preview_size (GTK_PREVIEW (widget), width, height);
gimp_pixel_rgn_init (&srcPR, drawable, x1, y1, x2, y2, FALSE, FALSE);
even = g_malloc (width * 3);
odd = g_malloc (width * 3);
src = g_malloc (width * bpp);
preview_cache = g_malloc(width * bpp * height);
preview_cache_rowstride = width * bpp;
preview_cache_bpp = bpp;
for (y = 0; y < height; y++)
{
gimp_pixel_rgn_get_row (&srcPR, src, x1, y + y1, width);
memcpy(preview_cache + (y*width*bpp),src,width*bpp);
}
for (y = 0; y < height; y++)
{
preview_do_row(y,width,even,odd,preview_cache + (y*width*bpp));
}
g_free (even);
g_free (odd);
g_free (src);
}