/* edge filter for GIMP
* -Peter Mattis
*
* This filter performs edge detection on the input image.
* The code for this filter is based on "pgmedge", a program
* that is part of the netpbm package.
*
* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* 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 .
*/
/* pgmedge.c - edge-detect a portable graymap
*
* Copyright (C) 1989 by Jef Poskanzer.
*/
/*
* Ported to GIMP Plug-in API 1.0
* version 1.07
* This version requires GIMP v0.99.10 or above.
*
* This plug-in performs edge detection. The code is based on edge.c
* for GIMP 0.54 by Peter Mattis.
*
* Eiichi Takamori
* http://ha1.seikyou.ne.jp/home/taka/gimp/
*
* Tips: you can enter arbitrary value into entry.
* (not bounded between 1.0 and 10.0)
*/
/* 29 July 2003 Dave Neary
* Added more edge detection routines, from the thin_line
* plug-in by iccii
*/
#include "config.h"
#include
#include
#include "libgimp/stdplugins-intl.h"
/* Some useful macros */
#define PLUG_IN_PROC "plug-in-edge"
#define PLUG_IN_BINARY "edge"
#define PLUG_IN_ROLE "gimp-edge"
#define TILE_CACHE_SIZE 48
enum
{
SOBEL,
PREWITT,
GRADIENT,
ROBERTS,
DIFFERENTIAL,
LAPLACE
};
typedef struct
{
gdouble amount;
gint edgemode;
gint wrapmode;
} EdgeVals;
/*
* Function prototypes.
*/
static void query (void);
static void run (const gchar *name,
gint nparams,
const GimpParam *param,
gint *nreturn_vals,
GimpParam **return_vals);
static void edge (GimpDrawable *drawable);
static gboolean edge_dialog (GimpDrawable *drawable);
static void edge_preview_update (GimpPreview *preview);
static gint edge_detect (const guchar *data);
static gint prewitt (const guchar *data);
static gint gradient (const guchar *data);
static gint roberts (const guchar *data);
static gint differential (const guchar *data);
static gint laplace (const guchar *data);
static gint sobel (const guchar *data);
/***** Local vars *****/
const GimpPlugInInfo PLUG_IN_INFO =
{
NULL, /* init */
NULL, /* quit */
query, /* query */
run, /* run */
};
static EdgeVals evals =
{
2.0, /* amount */
SOBEL, /* Edge detection algorithm */
GIMP_PIXEL_FETCHER_EDGE_SMEAR /* wrapmode */
};
/***** Functions *****/
MAIN ()
static void
query (void)
{
static const GimpParamDef args[] =
{
{ GIMP_PDB_INT32, "run-mode", "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }" },
{ GIMP_PDB_IMAGE, "image", "Input image (unused)" },
{ GIMP_PDB_DRAWABLE, "drawable", "Input drawable" },
{ GIMP_PDB_FLOAT, "amount", "Edge detection amount" },
{ GIMP_PDB_INT32, "wrapmode", "Edge detection behavior { WRAP (1), SMEAR (2), BLACK (3) }" },
{ GIMP_PDB_INT32, "edgemode", "Edge detection algorithm { SOBEL (0), PREWITT (1), GRADIENT (2), ROBERTS (3), DIFFERENTIAL (4), LAPLACE (5) }" }
};
const gchar *help_string =
"Perform edge detection on the contents of the specified drawable."
"AMOUNT is an arbitrary constant, WRAPMODE is like displace plug-in "
"(useful for tilable image). EDGEMODE sets the kind of matrix "
"transform applied to the pixels, SOBEL was the method used in older "
"versions.";
gimp_install_procedure (PLUG_IN_PROC,
N_("Several simple methods for detecting edges"),
help_string,
"Peter Mattis & (ported to 1.0 by) Eiichi Takamori",
"Peter Mattis",
"1996",
N_("_Edge..."),
"RGB*, GRAY*",
GIMP_PLUGIN,
G_N_ELEMENTS (args), 0,
args, NULL);
gimp_plugin_menu_register (PLUG_IN_PROC, "/Filters/Edge-Detect");
}
static void
run (const gchar *name,
gint nparams,
const GimpParam *param,
gint *nreturn_vals,
GimpParam **return_vals)
{
static GimpParam values[1];
GimpRunMode run_mode;
GimpPDBStatusType status = GIMP_PDB_SUCCESS;
GimpDrawable *drawable;
run_mode = param[0].data.d_int32;
INIT_I18N ();
/* Get the specified drawable */
drawable = gimp_drawable_get (param[2].data.d_drawable);
*nreturn_vals = 1;
*return_vals = values;
values[0].type = GIMP_PDB_STATUS;
values[0].data.d_status = status;
switch (run_mode)
{
case GIMP_RUN_INTERACTIVE:
/* Possibly retrieve data */
gimp_get_data (PLUG_IN_PROC, &evals);
/* First acquire information with a dialog */
if (! edge_dialog (drawable))
return;
break;
case GIMP_RUN_NONINTERACTIVE:
/* Make sure all the arguments are there! */
if (nparams != 5 && nparams != 6)
{
status = GIMP_PDB_CALLING_ERROR;
}
if (status == GIMP_PDB_SUCCESS)
{
evals.amount = param[3].data.d_float;
evals.wrapmode = param[4].data.d_int32;
evals.edgemode = nparams > 5 ? param[5].data.d_int32 : SOBEL;
}
break;
case GIMP_RUN_WITH_LAST_VALS:
/* Possibly retrieve data */
gimp_get_data (PLUG_IN_PROC, &evals);
break;
default:
break;
}
/* make sure the drawable exist and is not indexed */
if (gimp_drawable_is_rgb (drawable->drawable_id) ||
gimp_drawable_is_gray (drawable->drawable_id))
{
gimp_progress_init (_("Edge detection"));
/* set the tile cache size */
gimp_tile_cache_ntiles (TILE_CACHE_SIZE);
/* run the edge effect */
edge (drawable);
if (run_mode != GIMP_RUN_NONINTERACTIVE)
gimp_displays_flush ();
/* Store data */
if (run_mode == GIMP_RUN_INTERACTIVE)
gimp_set_data (PLUG_IN_PROC, &evals, sizeof (EdgeVals));
}
else
{
/* gimp_message ("edge: cannot operate on indexed color images"); */
status = GIMP_PDB_EXECUTION_ERROR;
}
values[0].data.d_status = status;
gimp_drawable_detach (drawable);
}
/********************************************************/
/* Edge Detection main */
/********************************************************/
static void
edge (GimpDrawable *drawable)
{
GimpPixelRgn src_rgn, dest_rgn;
gpointer pr;
GimpPixelFetcher *pft;
guchar *srcrow, *src;
guchar *destrow, *dest;
guchar pix00[4], pix01[4], pix02[4];
guchar pix10[4], pix11[4], pix12[4];
guchar pix20[4], pix21[4], pix22[4];
gint alpha;
gboolean has_alpha;
gint chan;
gint x, y;
gint x1, y1, x2, y2;
gint cur_progress;
gint max_progress;
gdouble per_progress;
if (evals.amount < 1.0)
evals.amount = 1.0;
pft = gimp_pixel_fetcher_new (drawable, FALSE);
gimp_pixel_fetcher_set_edge_mode (pft, evals.wrapmode);
gimp_drawable_mask_bounds (drawable->drawable_id, &x1, &y1, &x2, &y2);
alpha = gimp_drawable_bpp (drawable->drawable_id);
has_alpha = gimp_drawable_has_alpha (drawable->drawable_id);
if (has_alpha)
alpha--;
cur_progress = 0;
per_progress = 0.0;
max_progress = (x2 - x1) * (y2 - y1) / 100;
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);
for (pr = gimp_pixel_rgns_register (2, &src_rgn, &dest_rgn);
pr != NULL;
pr = gimp_pixel_rgns_process (pr))
{
srcrow = src_rgn.data;
destrow = dest_rgn.data;
for (y = dest_rgn.y;
y < (dest_rgn.y + dest_rgn.h);
y++, srcrow += src_rgn.rowstride, destrow += dest_rgn.rowstride)
{
src = srcrow;
dest = destrow;
for (x = dest_rgn.x;
x < (dest_rgn.x + dest_rgn.w);
x++, src += src_rgn.bpp, dest += dest_rgn.bpp)
{
if (dest_rgn.x < x && x < dest_rgn.x + dest_rgn.w - 2 &&
dest_rgn.y < y && y < dest_rgn.y + dest_rgn.h - 2)
{
/*
* 3x3 kernel is inside of the tile -- do fast
* version
*/
for (chan = 0; chan < alpha; chan++)
{
/* get the 3x3 kernel into a guchar array,
* and send it to edge_detect */
guchar kernel[9];
gint i,j;
#define PIX(X,Y) src[ (Y-1)*(int)src_rgn.rowstride + (X-1)*(int)src_rgn.bpp + chan ]
/* make convolution */
for(i = 0; i < 3; i++)
for(j = 0; j < 3; j++)
kernel[3*i + j] = PIX(i,j);
#undef PIX
dest[chan] = edge_detect (kernel);
}
}
else
{
/*
* The kernel is not inside of the tile -- do slow
* version
*/
gimp_pixel_fetcher_get_pixel (pft, x-1, y-1, pix00);
gimp_pixel_fetcher_get_pixel (pft, x , y-1, pix10);
gimp_pixel_fetcher_get_pixel (pft, x+1, y-1, pix20);
gimp_pixel_fetcher_get_pixel (pft, x-1, y , pix01);
gimp_pixel_fetcher_get_pixel (pft, x , y , pix11);
gimp_pixel_fetcher_get_pixel (pft, x+1, y , pix21);
gimp_pixel_fetcher_get_pixel (pft, x-1, y+1, pix02);
gimp_pixel_fetcher_get_pixel (pft, x , y+1, pix12);
gimp_pixel_fetcher_get_pixel (pft, x+1, y+1, pix22);
for (chan = 0; chan < alpha; chan++)
{
guchar kernel[9];
kernel[0] = pix00[chan];
kernel[1] = pix01[chan];
kernel[2] = pix02[chan];
kernel[3] = pix10[chan];
kernel[4] = pix11[chan];
kernel[5] = pix12[chan];
kernel[6] = pix20[chan];
kernel[7] = pix21[chan];
kernel[8] = pix22[chan];
dest[chan] = edge_detect (kernel);
}
}
if (has_alpha)
dest[alpha] = src[alpha];
}
}
cur_progress += dest_rgn.w * dest_rgn.h;
if (cur_progress > max_progress)
{
cur_progress = cur_progress - max_progress;
per_progress = per_progress + 0.01;
gimp_progress_update (per_progress);
}
}
gimp_progress_update (1.0);
gimp_pixel_fetcher_destroy (pft);
gimp_drawable_flush (drawable);
gimp_drawable_merge_shadow (drawable->drawable_id, TRUE);
gimp_drawable_update (drawable->drawable_id, x1, y1, (x2 - x1), (y2 - y1));
}
/* *********************** Edge Detection ******************** */
/*
* Edge detect switcher function
*/
static gint
edge_detect (const guchar *data)
{
gint ret;
switch (evals.edgemode)
{
case SOBEL:
ret = sobel (data);
break;
case PREWITT:
ret = prewitt (data);
break;
case GRADIENT:
ret = gradient (data);
break;
case ROBERTS:
ret = roberts (data);
break;
case DIFFERENTIAL:
ret = differential (data);
break;
case LAPLACE:
ret = laplace (data);
break;
default:
ret = -1;
break;
}
return CLAMP0255 (ret);
}
/*
* Sobel Edge detector
*/
static gint
sobel (const guchar *data)
{
const gint v_kernel[9] = { -1, 0, 1,
-2, 0, 2,
-1, 0, 1 };
const gint h_kernel[9] = { -1, -2, -1,
0, 0, 0,
1, 2, 1 };
gint i;
gint v_grad, h_grad;
for (i = 0, v_grad = 0, h_grad = 0; i < 9; i++)
{
v_grad += v_kernel[i] * data[i];
h_grad += h_kernel[i] * data[i];
}
return sqrt (v_grad * v_grad * evals.amount +
h_grad * h_grad * evals.amount);
}
/*
* Edge detector via template matting
* -- Prewitt Compass
*/
static gint
prewitt (const guchar *data)
{
gint k, max;
gint m[8];
m[0] = data [0] + data [1] + data [2]
+ data [3] - 2*data [4] + data [5]
- data [6] - data [7] - data [8];
m[1] = data [0] + data [1] + data [2]
+ data [3] - 2*data [4] - data [5]
+ data [6] - data [7] - data [8];
m[2] = data [0] + data [1] - data [2]
+ data [3] - 2*data [4] - data [5]
+ data [6] + data [7] - data [8];
m[3] = data [0] - data [1] - data [2]
+ data [3] - 2*data [4] - data [5]
+ data [6] + data [7] + data [8];
m[4] = - data [0] - data [1] - data [2]
+ data [3] - 2*data [4] + data [5]
+ data [6] + data [7] + data [8];
m[5] = - data [0] - data [1] + data [2]
- data [3] - 2*data [4] + data [5]
+ data [6] + data [7] + data [8];
m[6] = - data [0] + data [1] + data [2]
- data [3] - 2*data [4] + data [5]
- data [6] + data [7] + data [8];
m[7] = data [0] + data [1] + data [2]
- data [3] - 2*data [4] + data [5]
- data [6] - data [7] + data [8];
for (k = 0, max = 0; k < 8; k++)
if (max < m[k])
max = m[k];
return evals.amount * max;
}
/*
* Gradient Edge detector
*/
static gint
gradient (const guchar *data)
{
const gint v_kernel[9] = { 0, 0, 0,
0, 4, -4,
0, 0, 0 };
const gint h_kernel[9] = { 0, 0, 0,
0, -4, 0,
0, 4, 0 };
gint i;
gint v_grad, h_grad;
for (i = 0, v_grad = 0, h_grad = 0; i < 9; i++)
{
v_grad += v_kernel[i] * data[i];
h_grad += h_kernel[i] * data[i];
}
return sqrt (v_grad * v_grad * evals.amount +
h_grad * h_grad * evals.amount);
}
/*
* Roberts Edge detector
*/
static gint
roberts (const guchar *data)
{
const gint v_kernel[9] = { 0, 0, 0,
0, 4, 0,
0, 0, -4 };
const gint h_kernel[9] = { 0, 0, 0,
0, 0, 4,
0, -4, 0 };
gint i;
gint v_grad, h_grad;
for (i = 0, v_grad = 0, h_grad = 0; i < 9; i++)
{
v_grad += v_kernel[i] * data[i];
h_grad += h_kernel[i] * data[i];
}
return sqrt (v_grad * v_grad * evals.amount +
h_grad * h_grad * evals.amount);
}
/*
* Differential Edge detector
*/
static gint
differential (const guchar *data)
{
const gint v_kernel[9] = { 0, 0, 0,
0, 2, -2,
0, 2, -2 };
const gint h_kernel[9] = { 0, 0, 0,
0, -2, -2,
0, 2, 2 };
gint i;
gint v_grad, h_grad;
for (i = 0, v_grad = 0, h_grad = 0; i < 9; i++)
{
v_grad += v_kernel[i] * data[i];
h_grad += h_kernel[i] * data[i];
}
return sqrt (v_grad * v_grad * evals.amount +
h_grad * h_grad * evals.amount);
}
/*
* Laplace Edge detector
*/
static gint
laplace (const guchar *data)
{
const gint kernel[9] = { 1, 1, 1,
1, -8, 1,
1, 1, 1 };
gint i;
gint grad;
for (i = 0, grad = 0; i < 9; i++)
grad += kernel[i] * data[i];
return grad * evals.amount;
}
/*******************************************************/
/* Dialog */
/*******************************************************/
static gboolean
edge_dialog (GimpDrawable *drawable)
{
GtkWidget *dialog;
GtkWidget *main_vbox;
GtkWidget *preview;
GtkWidget *hbox;
GtkWidget *table;
GtkWidget *combo;
GtkWidget *toggle;
GtkObject *scale_data;
GSList *group = NULL;
gboolean run;
gboolean use_wrap = (evals.wrapmode == GIMP_PIXEL_FETCHER_EDGE_WRAP);
gboolean use_smear = (evals.wrapmode == GIMP_PIXEL_FETCHER_EDGE_SMEAR);
gboolean use_black = (evals.wrapmode == GIMP_PIXEL_FETCHER_EDGE_BLACK);
gimp_ui_init (PLUG_IN_BINARY, FALSE);
dialog = gimp_dialog_new (_("Edge Detection"), PLUG_IN_ROLE,
NULL, 0,
gimp_standard_help_func, PLUG_IN_PROC,
GTK_STOCK_CANCEL, GTK_RESPONSE_CANCEL,
GTK_STOCK_OK, GTK_RESPONSE_OK,
NULL);
gtk_dialog_set_alternative_button_order (GTK_DIALOG (dialog),
GTK_RESPONSE_OK,
GTK_RESPONSE_CANCEL,
-1);
gimp_window_set_transient (GTK_WINDOW (dialog));
main_vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 12);
gtk_box_pack_start (GTK_BOX (gtk_dialog_get_content_area (GTK_DIALOG (dialog))),
main_vbox, TRUE, TRUE, 0);
gtk_widget_show (main_vbox);
preview = gimp_drawable_preview_new (drawable, NULL);
gtk_box_pack_start (GTK_BOX (main_vbox), preview, TRUE, TRUE, 0);
gtk_widget_show (preview);
g_signal_connect (preview, "invalidated",
G_CALLBACK (edge_preview_update),
NULL);
table = gtk_table_new (3, 3, FALSE);
gtk_table_set_col_spacings (GTK_TABLE (table), 6);
gtk_table_set_row_spacings (GTK_TABLE (table), 6);
gtk_box_pack_start (GTK_BOX (main_vbox), table, FALSE, FALSE, 0);
gtk_widget_show (table);
combo = gimp_int_combo_box_new (_("Sobel"), SOBEL,
_("Prewitt compass"), PREWITT,
_("Gradient"), GRADIENT,
_("Roberts"), ROBERTS,
_("Differential"), DIFFERENTIAL,
_("Laplace"), LAPLACE,
NULL);
gimp_int_combo_box_connect (GIMP_INT_COMBO_BOX (combo),
evals.edgemode,
G_CALLBACK (gimp_int_combo_box_get_active),
&evals.edgemode);
gimp_table_attach_aligned (GTK_TABLE (table), 0, 0,
_("_Algorithm:"), 0.0, 0.5,
combo, 2, FALSE);
g_signal_connect_swapped (combo, "changed",
G_CALLBACK (gimp_preview_invalidate),
preview);
/* Label, scale, entry for evals.amount */
scale_data = gimp_scale_entry_new (GTK_TABLE (table), 0, 1,
_("A_mount:"), 100, 0,
evals.amount, 1.0, 10.0, 0.1, 1.0, 1,
FALSE, 1.0, G_MAXFLOAT,
NULL, NULL);
g_signal_connect (scale_data, "value-changed",
G_CALLBACK (gimp_double_adjustment_update),
&evals.amount);
g_signal_connect_swapped (scale_data, "value-changed",
G_CALLBACK (gimp_preview_invalidate),
preview);
/* Radio buttons WRAP, SMEAR, BLACK */
hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 4);
gtk_table_attach (GTK_TABLE (table), hbox, 0, 3, 2, 3,
GTK_FILL, GTK_FILL, 0, 0);
gtk_widget_show (hbox);
toggle = gtk_radio_button_new_with_mnemonic (group, _("_Wrap"));
group = gtk_radio_button_get_group (GTK_RADIO_BUTTON (toggle));
gtk_box_pack_start (GTK_BOX (hbox), toggle, TRUE, TRUE, 0);
gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle), use_wrap);
gtk_widget_show (toggle);
g_signal_connect (toggle, "toggled",
G_CALLBACK (gimp_toggle_button_update),
&use_wrap);
g_signal_connect_swapped (toggle, "toggled",
G_CALLBACK (gimp_preview_invalidate),
preview);
toggle = gtk_radio_button_new_with_mnemonic (group, _("_Smear"));
group = gtk_radio_button_get_group (GTK_RADIO_BUTTON (toggle));
gtk_box_pack_start (GTK_BOX (hbox), toggle, TRUE, TRUE, 0);
gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle), use_smear);
gtk_widget_show (toggle);
g_signal_connect (toggle, "toggled",
G_CALLBACK (gimp_toggle_button_update),
&use_smear);
g_signal_connect_swapped (toggle, "toggled",
G_CALLBACK (gimp_preview_invalidate),
preview);
toggle = gtk_radio_button_new_with_mnemonic (group, _("_Black"));
group = gtk_radio_button_get_group (GTK_RADIO_BUTTON (toggle));
gtk_box_pack_start (GTK_BOX (hbox), toggle, TRUE, TRUE, 0);
gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle), use_black);
gtk_widget_show (toggle);
g_signal_connect (toggle, "toggled",
G_CALLBACK (gimp_toggle_button_update),
&use_black);
g_signal_connect_swapped (toggle, "toggled",
G_CALLBACK (gimp_preview_invalidate),
preview);
gtk_widget_show (dialog);
run = (gimp_dialog_run (GIMP_DIALOG (dialog)) == GTK_RESPONSE_OK);
gtk_widget_destroy (dialog);
if (use_wrap)
evals.wrapmode = GIMP_PIXEL_FETCHER_EDGE_WRAP;
else if (use_smear)
evals.wrapmode = GIMP_PIXEL_FETCHER_EDGE_SMEAR;
else if (use_black)
evals.wrapmode = GIMP_PIXEL_FETCHER_EDGE_BLACK;
return run;
}
static void
edge_preview_update (GimpPreview *preview)
{
/* drawable */
GimpDrawable *drawable;
glong bytes;
gint alpha;
gboolean has_alpha;
/* preview */
guchar *src = NULL; /* Buffer to hold source image */
guchar *render_buffer = NULL; /* Buffer to hold rendered image */
guchar *dest;
gint width; /* Width of preview widget */
gint height; /* Height of preview widget */
gint x1; /* Upper-left X of preview */
gint y1; /* Upper-left Y of preview */
GimpPixelRgn srcPR; /* Pixel regions */
/* algorithm */
gint x, y;
/* Get drawable info */
drawable =
gimp_drawable_preview_get_drawable (GIMP_DRAWABLE_PREVIEW (preview));
bytes = gimp_drawable_bpp (drawable->drawable_id);
alpha = bytes;
has_alpha = gimp_drawable_has_alpha (drawable->drawable_id);
if (has_alpha)
alpha--;
/*
* Setup for filter...
*/
gimp_preview_get_position (preview, &x1, &y1);
gimp_preview_get_size (preview, &width, &height);
/* initialize pixel regions */
gimp_pixel_rgn_init (&srcPR, drawable,
x1, y1, width, height, FALSE, FALSE);
src = g_new (guchar, width * height * bytes);
render_buffer = g_new (guchar, width * height * bytes);
/* render image */
gimp_pixel_rgn_get_rect(&srcPR, src, x1, y1, width, height);
dest = render_buffer;
/* render algorithm */
for (y = 0 ; y < height ; y++)
for (x = 0 ; x < width ; x++)
{
gint chan;
for (chan = 0; chan < alpha; chan++)
{
guchar kernel[9];
#define SRC(X,Y) src[bytes * (CLAMP((X), 0, width-1) + \
width * CLAMP((Y), 0, height-1)) + chan]
kernel[0] = SRC (x - 1, y - 1);
kernel[1] = SRC (x - 1, y );
kernel[2] = SRC (x - 1, y + 1);
kernel[3] = SRC (x , y - 1);
kernel[4] = SRC (x , y );
kernel[5] = SRC (x , y + 1);
kernel[6] = SRC (x + 1, y - 1);
kernel[7] = SRC (x + 1, y );
kernel[8] = SRC (x + 1, y + 1);
#undef SRC
dest[chan] = edge_detect (kernel);
}
if (has_alpha)
dest[alpha] = src[bytes * (x + width * y) + alpha];
dest += bytes;
}
/*
* Draw the preview image on the screen...
*/
gimp_preview_draw_buffer (preview, render_buffer, width * bytes);
g_free (render_buffer);
g_free (src);
}