/*
* Copyright (c) 1996, 1998, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* This file implements some of the standard utility procedures used
* by the image conversion package.
*/
#include "img_globals.h"
#include "java_awt_image_IndexColorModel.h"
#include "java_awt_image_DirectColorModel.h"
#include "java_awt_Transparency.h"
/*
* This function constructs an 8x8 ordered dither array which can be
* used to dither data into an output range with discreet values that
* differ by the value specified as quantum. A monochrome screen would
* use a dither array constructed with the quantum 256.
* The array values produced are unsigned and intended to be used with
* a lookup table which returns the next color darker than the error
* adjusted color used as the index.
*/
void
make_uns_ordered_dither_array(uns_ordered_dither_array oda,
int quantum)
{
int i, j, k;
oda[0][0] = 0;
for (k = 1; k < 8; k *= 2) {
for (i = 0; i < k; i++) {
for (j = 0; j < k; j++) {
oda[ i ][ j ] = oda[i][j] * 4;
oda[i+k][j+k] = oda[i][j] + 1;
oda[ i ][j+k] = oda[i][j] + 2;
oda[i+k][ j ] = oda[i][j] + 3;
}
}
}
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
oda[i][j] = oda[i][j] * quantum / 64;
}
}
}
/*
* This function constructs an 8x8 ordered dither array which can be
* used to dither data into an output range with discreet values that
* are distributed over the range from minerr to maxerr around a given
* target color value.
* The array values produced are signed and intended to be used with
* a lookup table which returns the closest color to the error adjusted
* color used as an index.
*/
void
make_sgn_ordered_dither_array(char* oda, int minerr, int maxerr)
{
int i, j, k;
oda[0] = 0;
for (k = 1; k < 8; k *= 2) {
for (i = 0; i < k; i++) {
for (j = 0; j < k; j++) {
oda[(i<<3) + j] = oda[(i<<3)+j] * 4;
oda[((i+k)<<3) + j+k] = oda[(i<<3)+j] + 1;
oda[(i<<3) + j+k] = oda[(i<<3)+j] + 2;
oda[((i+k)<<3) + j] = oda[(i<<3)+j] + 3;
}
}
}
k = 0;
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
oda[k] = oda[k] * (maxerr - minerr) / 64 + minerr;
k++;
}
}
}
#ifdef TESTING
#include <stdio.h>
/* Function to test the ordered dither error matrix initialization function. */
main(int argc, char **argv)
{
int i, j;
int quantum;
int max, val;
uns_ordered_dither_array oda;
if (argc > 1) {
quantum = atoi(argv[1]);
} else {
quantum = 64;
}
make_uns_ordered_dither_array(oda, quantum);
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
val = oda[i][j];
printf("%4d", val);
if (max < val) {
max = val;
}
}
printf("\n");
}
printf("\nmax = %d\n", max);
}
#endif /* TESTING */