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/*
* "$Id: dither-ordered.c,v 1.17.18.1 2007/12/15 20:35:44 rlk Exp $"
*
* Ordered dither algorithm
*
* Copyright 1997-2003 Michael Sweet (mike@easysw.com) and
* Robert Krawitz (rlk@alum.mit.edu)
*
* 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.
*
* Revision History:
*
* See ChangeLog
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <gutenprint/gutenprint.h>
#include "gutenprint-internal.h"
#include <gutenprint/gutenprint-intl-internal.h>
#include "dither-impl.h"
#include "dither-inlined-functions.h"
static inline void
print_color_ordered(const stpi_dither_t *d, stpi_dither_channel_t *dc, int val,
int x, int y, unsigned char bit, int length)
{
int i;
int j;
unsigned bits;
int levels = dc->nlevels - 1;
/*
* Look for the appropriate range into which the input value falls.
* Notice that we use the input, not the error, to decide what dot type
* to print (if any). We actually use the "density" input to permit
* the caller to use something other that simply the input value, if it's
* desired to use some function of overall density, rather than just
* this color's input, for this purpose.
*/
for (i = levels; i >= 0; i--)
{
stpi_dither_segment_t *dd = &(dc->ranges[i]);
if (val > dd->lower->value)
{
/*
* Where are we within the range.
*/
unsigned rangepoint = val - dd->lower->value;
if (dd->value_span < 65535)
rangepoint = rangepoint * 65535 / dd->value_span;
if (rangepoint >= ditherpoint(d, &(dc->dithermat), x))
bits = dd->upper->bits;
else
bits = dd->lower->bits;
if (bits)
{
unsigned char *tptr = dc->ptr + d->ptr_offset;
/*
* Lay down all of the bits in the pixel.
*/
set_row_ends(dc, x);
for (j = 1; j <= bits; j += j, tptr += length)
{
if (j & bits)
tptr[0] |= bit;
}
}
return;
}
}
}
void
stpi_dither_ordered(stp_vars_t *v,
int row,
const unsigned short *raw,
int duplicate_line,
int zero_mask,
const unsigned char *mask)
{
stpi_dither_t *d = (stpi_dither_t *) stp_get_component_data(v, "Dither");
int x,
length;
unsigned char bit;
int i;
int one_bit_only = 1;
int xerror, xstep, xmod;
if ((zero_mask & ((1 << CHANNEL_COUNT(d)) - 1)) ==
((1 << CHANNEL_COUNT(d)) - 1))
return;
length = (d->dst_width + 7) / 8;
bit = 128;
xstep = CHANNEL_COUNT(d) * (d->src_width / d->dst_width);
xmod = d->src_width % d->dst_width;
xerror = 0;
for (i = 0; i < CHANNEL_COUNT(d); i++)
{
stpi_dither_channel_t *dc = &(CHANNEL(d, i));
if (dc->nlevels != 1 || dc->ranges[0].upper->bits != 1)
one_bit_only = 0;
}
if (one_bit_only)
{
for (x = 0; x < d->dst_width; x ++)
{
if (!mask || (*(mask + d->ptr_offset) & bit))
{
for (i = 0; i < CHANNEL_COUNT(d); i++)
{
if (raw[i] &&
raw[i] >= ditherpoint(d, &(CHANNEL(d, i).dithermat), x))
{
set_row_ends(&(CHANNEL(d, i)), x);
CHANNEL(d, i).ptr[d->ptr_offset] |= bit;
}
}
}
ADVANCE_UNIDIRECTIONAL(d, bit, raw, CHANNEL_COUNT(d),
xerror, xstep, xmod);
}
}
else
{
for (x = 0; x != d->dst_width; x ++)
{
if (!mask || (*(mask + d->ptr_offset) & bit))
{
for (i = 0; i < CHANNEL_COUNT(d); i++)
{
if (CHANNEL(d, i).ptr && raw[i])
print_color_ordered(d, &(CHANNEL(d, i)), raw[i], x, row,
bit, length);
}
}
ADVANCE_UNIDIRECTIONAL(d, bit, raw, CHANNEL_COUNT(d), xerror,
xstep, xmod);
}
}
}
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