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gimp/plug-ins/common/colortoalpha.c

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/*
* Color To Alpha plug-in v1.0 by Seth Burgess, sjburges@gimp.org 1999/05/14
* with algorithm by clahey
*/
/* The GIMP -- an 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 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.
*/
#include <stdio.h>
#include <stdlib.h>
#include "gtk/gtk.h"
#include "libgimp/gimp.h"
#include "libgimp/gimpui.h"
#include "libgimp/stdplugins-intl.h"
#define PRV_WIDTH 40
#define PRV_HEIGHT 20
typedef struct {
guchar color[3];
} C2AValues;
typedef struct {
gint run;
} C2AInterface;
typedef struct {
GtkWidget *color_button;
} C2APreview;
/* Declare local functions.
*/
static void query (void);
static void run (char *name,
int nparams,
GParam *param,
int *nreturn_vals,
GParam **return_vals);
static void toalpha (GDrawable *drawable);
static void toalpha_render_row (const guchar *src_row,
guchar *dest_row,
gint row_width,
const gint bytes);
/* UI stuff */
static gint colortoalpha_dialog (GDrawable *drawable);
static void C2A_close_callback (GtkWidget *widget, gpointer data);
static void C2A_ok_callback (GtkWidget *widget, gpointer data);
static GRunModeType run_mode;
GPlugInInfo PLUG_IN_INFO =
{
NULL, /* init_proc */
NULL, /* quit_proc */
query, /* query_proc */
run, /* run_proc */
};
static C2AValues pvals =
{
{255, 255, 255} /* white default */
};
static C2AInterface pint =
{
FALSE
};
static C2APreview ppreview =
{
NULL
};
MAIN ()
static void
query ()
{
static GParamDef args[] =
{
{ PARAM_INT32, "run_mode", "Interactive, non-interactive" },
{ PARAM_IMAGE, "image", "Input image (unused)" },
{ PARAM_DRAWABLE, "drawable", "Input drawable" },
{ PARAM_COLOR, "color", "Color to remove"},
};
static GParamDef *return_vals = NULL;
static int nargs = sizeof (args) / sizeof (args[0]);
static int nreturn_vals = 0;
gimp_install_procedure ("plug_in_colortoalpha",
"Convert the color in an image to alpha",
"This replaces as much of a given color as possible in each pixel with a corresponding amount of alpha, then readjusts the color accordingly.",
"Seth Burgess",
"Seth Burgess <sjburges@gimp.org>",
"7th Aug 1999",
"<Image>/Filters/Colors/Color To Alpha",
"RGBA",
PROC_PLUG_IN,
nargs, nreturn_vals,
args, return_vals);
}
static void
run (char *name,
int nparams,
GParam *param,
int *nreturn_vals,
GParam **return_vals)
{
static GParam values[1];
GDrawable *drawable;
gint32 image_ID;
GStatusType status = STATUS_SUCCESS;
run_mode = param[0].data.d_int32;
*nreturn_vals = 1;
*return_vals = values;
INIT_I18N_UI();
values[0].type = PARAM_STATUS;
values[0].data.d_status = status;
/* Get the specified drawable */
drawable = gimp_drawable_get (param[2].data.d_drawable);
image_ID = param[1].data.d_image;
switch (run_mode)
{
case RUN_INTERACTIVE:
gimp_get_data ("plug_in_colortoalpha", &pvals);
if (! colortoalpha_dialog (drawable ))
{
gimp_drawable_detach (drawable);
return;
}
break;
case RUN_NONINTERACTIVE:
if (nparams != 3)
status = STATUS_CALLING_ERROR;
if (status == STATUS_SUCCESS)
{
pvals.color[0] = param[3].data.d_color.red;
pvals.color[1] = param[3].data.d_color.green;
pvals.color[2] = param[3].data.d_color.blue;
}
break;
case RUN_WITH_LAST_VALS:
gimp_get_data ("plug_in_colortoalpha", &pvals);
break;
default:
break;
}
if (status == STATUS_SUCCESS)
{
/* Make sure that the drawable is indexed or RGB color */
if (gimp_drawable_color (drawable->id) &&
gimp_drawable_has_alpha(drawable->id))
{
if (run_mode != RUN_NONINTERACTIVE)
gimp_progress_init ("Removing color...");
toalpha (drawable);
gimp_displays_flush ();
}
}
if (run_mode == RUN_INTERACTIVE)
gimp_set_data ("plug_in_colortoalpha", &pvals, sizeof (pvals));
values[0].data.d_status = status;
gimp_drawable_detach (drawable);
}
void
colortoalpha (float *a1,
float *a2,
float *a3,
float *a4,
float c1,
float c2,
float c3)
{
float alpha1, alpha2, alpha3;
if ( *a1 > c1 )
alpha1 = (*a1 - c1)/(255.0-c1);
else if ( *a1 < c1 )
alpha1 = (c1 - *a1)/(c1);
else alpha1 = 0.0;
if ( *a2 > c2 )
alpha2 = (*a2 - c2)/(255.0-c2);
else if ( *a2 < c2 )
alpha2 = (c2 - *a2)/(c2);
else alpha2 = 0.0;
if ( *a3 > c3 )
alpha3 = (*a3 - c3)/(255.0-c3);
else if ( *a3 < c3 )
alpha3 = (c3 - *a3)/(c3);
else alpha3 = 0.0;
if ( alpha1 > alpha2 )
if ( alpha1 > alpha3 )
{
*a4 = alpha1;
}
else
{
*a4 = alpha3;
}
else
if ( alpha2 > alpha3 )
{
*a4 = alpha2;
}
else
{
*a4 = alpha3;
}
*a4 *= 255.0;
if ( *a4 < 1.0 )
return;
*a1 = 255.0 * (*a1-c1)/ *a4 + c1;
*a2 = 255.0 * (*a2-c2)/ *a4 + c2;
*a3 = 255.0 * (*a3-c3)/ *a4 + c3;
}
/*
<clahey> so if a1 > c1, a2 > c2, and a3 > c2 and a1 - c1 > a2-c2, a3-c3, then a1 = b1 * alpha + c1 * (1-alpha) So, maximizing alpha without taking b1 above 1 gives a1 = alpha + c1(1-alpha) and therefore alpha = (a1-c1)/(1-c1).
<AmJur2d> eek! math!
> AmJur2d runs and hides behind a library carrel
<sjburges> clahey: btw, the ordering of that a2, a3 in the white->alpha didn't matter
<clahey> sjburges: You mean that it could be either a1, a2, a3 or a1, a3, a2?
<sjburges> yeah
<sjburges> because neither one uses the other
<clahey> sjburges: That's exactly as it should be. They are both just getting reduced to the same amount, limited by the the darkest color.
<clahey> Then a2 = b2 * alpha + c2 * ( 1- alpha). Solving for b2 gives b2 = (a1-c2)/alpha + c2.
<sjburges> yeah
<jlb> xachbot, url holy wars
<jlb> xachbot, url wars
<clahey> That gives us are formula for if the background is darker than the foreground? Yep.
<clahey> Next if a1 < c1, a2 < c2, a3 < c3, and c1-a1 > c2-a2, c3-a3, and by our desired result a1 = b1 * alpha + c1 * (1-alpha), we maximize alpha without taking b1 negative gives alpha = 1-a1/c1.
<clahey> And then again, b2 = (a2-c2)/alpha + c2 by the same formula. (Actually, I think we can use that formula for all cases, though it may possibly introduce rounding error.
<clahey> sjburges: I like the idea of using floats to avoid rounding error. Good call.
<clahey> It's cool to be able to replace all the black in an image with another color. It'
*/
static void
toalpha_render_row (const guchar *src_data,
guchar *dest_data,
gint col, /* row width in pixels */
const gint bytes)
{
while (col--)
{
float v1, v2, v3, v4;
v1 = (float)src_data[col*bytes ];
v2 = (float)src_data[col*bytes +1];
v3 = (float)src_data[col*bytes +2];
v4 = (float)src_data[col*bytes +3];
/* For brighter than the background the rule is to send the
farthest above the background as the first address.
However, since v1 < COLOR_RED, for example, all of these
are negative so we have to invert the operator to reduce
the amount of typing to fix the problem. :) */
colortoalpha(&v1, &v2, &v3, &v4,
(float)pvals.color[0],
(float)pvals.color[1],
(float)pvals.color[2]);
dest_data[col*bytes ] = (int)v1;
dest_data[col*bytes +1] = (int)v2;
dest_data[col*bytes +2] = (int)v3;
dest_data[col*bytes +3] = (int)v4;
}
}
static void
toalpha_render_region (const GPixelRgn srcPR,
const GPixelRgn destPR)
{
gint row;
guchar* src_ptr = srcPR.data;
guchar* dest_ptr = destPR.data;
for (row = 0; row < srcPR.h ; row++)
{
if (srcPR.bpp!=4) {
gimp_message("Not the proper bpp! \n");
exit(1);
}
toalpha_render_row (src_ptr, dest_ptr,
srcPR.w,
srcPR.bpp) ;
src_ptr += srcPR.rowstride;
dest_ptr += destPR.rowstride;
}
}
static void
toalpha (GDrawable *drawable)
{
GPixelRgn srcPR, destPR;
gint x1, y1, x2, y2;
gpointer pr;
gint total_area, area_so_far;
gint progress_skip;
/* Get the input area. This is the bounding box of the selection in
* the image (or the entire image if there is no selection). Only
* operating on the input area is simply an optimization. It doesn't
* need to be done for correct operation. (It simply makes it go
* faster, since fewer pixels need to be operated on).
*/
gimp_drawable_mask_bounds (drawable->id, &x1, &y1, &x2, &y2);
total_area = (x2 - x1) * (y2 - y1);
area_so_far = 0;
progress_skip = 0;
/* Initialize the pixel regions. */
gimp_pixel_rgn_init (&srcPR, drawable, x1, y1, (x2 - x1), (y2 - y1),
FALSE, FALSE);
gimp_pixel_rgn_init (&destPR, drawable, x1, y1, (x2 - x1), (y2 - y1),
TRUE, TRUE);
for (pr = gimp_pixel_rgns_register (2, &srcPR, &destPR);
pr != NULL;
pr = gimp_pixel_rgns_process (pr))
{
toalpha_render_region (srcPR, destPR);
if ((run_mode != RUN_NONINTERACTIVE))
{
area_so_far += srcPR.w * srcPR.h;
if (((progress_skip++)%10) == 0)
gimp_progress_update ((double) area_so_far / (double) total_area);
}
}
/* update the processed region */
gimp_drawable_flush (drawable);
gimp_drawable_merge_shadow (drawable->id, TRUE);
gimp_drawable_update (drawable->id, x1, y1, (x2 - x1), (y2 - y1));
}
static gint
colortoalpha_dialog (GDrawable *drawable)
{
GtkWidget *dlg;
GtkWidget *hbbox;
GtkWidget *button;
GtkWidget *table;
GtkWidget *label;
guchar *color_cube;
gchar **argv;
gint argc;
argc = 1;
argv = g_new (gchar *, 1);
argv[0] = g_strdup ("colortoalpha");
gtk_init (&argc, &argv);
gtk_rc_parse (gimp_gtkrc ());
gdk_set_use_xshm (gimp_use_xshm ());
gtk_preview_set_gamma (gimp_gamma ());
gtk_preview_set_install_cmap (gimp_install_cmap ());
color_cube = gimp_color_cube ();
gtk_preview_set_color_cube (color_cube[0], color_cube[1],
color_cube[2], color_cube[3]);
gtk_widget_set_default_visual (gtk_preview_get_visual ());
gtk_widget_set_default_colormap (gtk_preview_get_cmap ());
dlg = gtk_dialog_new ();
gtk_window_set_title (GTK_WINDOW (dlg), _("Color To Alpha"));
gtk_window_position (GTK_WINDOW (dlg), GTK_WIN_POS_MOUSE);
gtk_signal_connect (GTK_OBJECT (dlg), "destroy",
(GtkSignalFunc) C2A_close_callback,
NULL);
/* Action area */
gtk_container_set_border_width (GTK_CONTAINER (GTK_DIALOG (dlg)->action_area), 2);
gtk_box_set_homogeneous (GTK_BOX (GTK_DIALOG (dlg)->action_area), FALSE);
hbbox = gtk_hbutton_box_new ();
gtk_button_box_set_spacing (GTK_BUTTON_BOX (hbbox), 4);
gtk_box_pack_end (GTK_BOX (GTK_DIALOG (dlg)->action_area), hbbox, FALSE, FALSE, 0);
gtk_widget_show (hbbox);
button = gtk_button_new_with_label (_("OK"));
GTK_WIDGET_SET_FLAGS (button, GTK_CAN_DEFAULT);
gtk_signal_connect (GTK_OBJECT (button), "clicked",
(GtkSignalFunc) C2A_ok_callback,
dlg);
gtk_box_pack_start (GTK_BOX (hbbox), button, FALSE, FALSE, 0);
gtk_widget_grab_default (button);
gtk_widget_show (button);
button = gtk_button_new_with_label (_("Cancel"));
GTK_WIDGET_SET_FLAGS (button, GTK_CAN_DEFAULT);
gtk_signal_connect_object (GTK_OBJECT (button), "clicked",
(GtkSignalFunc) gtk_widget_destroy,
GTK_OBJECT (dlg));
gtk_box_pack_start (GTK_BOX (hbbox), button, FALSE, FALSE, 0);
gtk_widget_show (button);
table = gtk_table_new (1, 3, FALSE);
label = gtk_label_new (_("From:"));
gtk_table_attach_defaults ( GTK_TABLE(table), label, 0, 1, 0, 1);
gtk_widget_show (label);
button = gimp_color_button_new (_("Color To Alpha Color Picker"),
PRV_WIDTH, PRV_HEIGHT,
pvals.color, 3);
gtk_table_attach( GTK_TABLE(table), button, 1, 2, 0, 1,
GTK_EXPAND, GTK_SHRINK, 4, 4) ;
gtk_widget_show(button);
ppreview.color_button = button;
label = gtk_label_new (_("to alpha"));
gtk_table_attach_defaults ( GTK_TABLE(table), label, 2, 3, 0, 1);
gtk_widget_show (label);
gtk_box_pack_start (GTK_BOX (GTK_DIALOG (dlg)->vbox), table, TRUE, TRUE, 0);
gtk_widget_show (table);
gtk_widget_show (dlg);
gtk_main ();
gdk_flush ();
return pint.run;
}
static void
C2A_close_callback (GtkWidget *widget,
gpointer data)
{
gtk_main_quit ();
}
static void
C2A_ok_callback (GtkWidget *widget,
gpointer data)
{
pint.run = TRUE;
gtk_widget_destroy (GTK_WIDGET (data));
}
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