/*
* Copyright (c) 1996, 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 contains macro definitions for the Encoding category of
* the macros used by the generic scaleloop function.
*
* This implementation uses an ordered dithering error matrix to
* produce a moderately high quality version of an image with only
* an 8-bit (or less) RGB colormap. The ordered dithering technique
* does not rely on the order in which the pixels are processed so
* this file can be used in cases where the ImageProducer has not
* specified the TopDownLeftRight delivery hint. The ordered dither
* technique is also much faster than the Floyd-Steinberg error diffusion
* algorithm so this implementation would also be appropriate for
* cases where performance is critical such as the processing of a
* video stream.
*
* This file can be used to provide the default implementation of the
* Encoding macros for RGB colormapped displays.
*/
/*
* These definitions vector the standard macro names to the "Color"
* versions of those macros only if the "DitherDeclared" keyword has
* not yet been defined elsewhere. The "DitherDeclared" keyword is
* also defined here to claim ownership of the primary implementation
* even though this file does not rely on the definitions in any other
* files.
*/
#ifndef DitherDeclared
#define DitherDeclared
#define DeclareDitherVars DeclareAllColorDitherVars
#define InitDither InitColorDither
#define StartDitherLine StartColorDitherLine
#define DitherPixel ColorDitherPixel
#define DitherBufComplete ColorDitherBufComplete
#endif
#define DeclareAllColorDitherVars \
DeclareColorDitherVars \
int relx, rely;
#define DeclareColorDitherVars \
extern uns_ordered_dither_array img_oda_red; \
extern uns_ordered_dither_array img_oda_green; \
extern uns_ordered_dither_array img_oda_blue;
#define InitColorDither(cvdata, clrdata, dstTW) \
do {} while (0)
#define StartColorDitherLine(cvdata, dstX1, dstY) \
do { \
relx = dstX1 & 7; \
rely = dstY & 7; \
} while (0)
/*
* The adjustments below are gross, but they are required due to
* the way color lookups are done.
* The second set of adjustments simply clips the values generated
* by the ordered dithering values to a limit of 256 which represents
* full intensity.
* The first set of adjustments prepares for the fact that when
* the final lookup is done, maximum intensity is represented by
* the value 256, but the input values go from 0 to 255. As a
* result, the maximum input intensity needs to be mapped from
* 255 to 256. The Floyd-Steinberg lookups use a rounding
* calculation to handle mapping the values near 255 to the maximum
* intensity, but ordered dithering uses a truncating calculation
* so the value 255 will be rounded down to the second highest
* intensity thereby causing an occasionaly dark pixel when rendering
* the maximum input intensity. Other intensities (less than 255)
* are left alone since modifying them would slightly disturb their
* error distribution. In particular, for red, the value 0xe0 has
* a maximum error of 0x1f added to it which must not be mapped to
* the maximum intensity since intensity 0xe0 can be represented
* exactly. So, a calculated 0xff (0xe0 + 0x1f) needs to be left
* less than 256, but a natural 255, or a calculated (>=) 256
* should be mapped to maximum intensity.
*/
#define ColorDitherPixel(dstX, dstY, pixel, red, green, blue) \
do { \
if (red == 255) { \
red = 256; \
} else { \
red += img_oda_red[relx][rely]; \
if (red > 255) red = 256; \
} \
if (green == 255) { \
green = 256; \
} else { \
green += img_oda_green[relx][rely]; \
if (green > 255) green = 256; \
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