| /* |
| * 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; \ |
| } \ |
| if (blue == 255) { \ |
| blue = 256; \ |
| } else { \ |
| blue += img_oda_blue[relx][rely]; \ |
| if (blue > 255) blue = 256; \ |
| } \ |
| pixel = ColorCubeOrdMapUns(red, green, blue); \ |
| relx = (relx + 1) & 7; \ |
| } while (0) |
| |
| #define ColorDitherBufComplete(cvdata, dstX1) \ |
| do {} while (0) |
