1 /* 2 * Copyright (c) 1996, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 /* 27 * This file contains macro definitions for the Encoding category of 28 * the macros used by the generic scaleloop function. 29 * 30 * This implementation uses an ordered dithering error matrix to 31 * produce a moderately high quality version of an image with only 32 * an 8-bit (or less) grayramp. The ordered dithering technique does 33 * not rely on the order in which the pixels are processed so this 34 * file can be used in cases where the ImageProducer has not specified 35 * the TopDownLeftRight delivery hint. The ordered dither technique 36 * is also much faster than the Floyd-Steinberg error diffusion 37 * algorithm so this implementation would also be appropriate for 38 * cases where performance is critical such as the processing of a 39 * video stream. 40 * 41 * This file can be used to provide the default implementation of the 42 * Encoding macros for grayscale displays. 43 */ 44 45 /* 46 * These definitions vector the standard macro names to the "Gray" 47 * versions of those macros only if the "DitherDeclared" keyword has 48 * not yet been defined elsewhere. The "DitherDeclared" keyword is 49 * also defined here to claim ownership of the primary implementation 50 * even though this file does not rely on the definitions in any other 51 * files. 52 */ 53 #ifndef DitherDeclared 54 #define DitherDeclared 55 #define DeclareDitherVars DeclareAllGrayDitherVars 56 #define InitDither InitGrayDither 57 #define StartDitherLine StartGrayDitherLine 58 #define DitherPixel GrayDitherPixel 59 #define DitherBufComplete GrayDitherBufComplete 60 #endif 61 62 #define DeclareAllGrayDitherVars \ 63 DeclareGrayDitherVars \ 64 int relx, rely; 65 66 #define DeclareGrayDitherVars \ 67 extern unsigned char img_grays[256]; \ 68 extern unsigned char img_bwgamma[256]; \ 69 extern sgn_ordered_dither_array img_oda_gray; 70 71 #define InitGrayDither(cvdata, clrdata, dstTW) \ 72 do {} while (0) 73 74 #define StartGrayDitherLine(cvdata, dstX1, dstY) \ 75 do { \ 76 relx = dstX1 & 7; \ 77 rely = dstY & 7; \ 78 } while (0) 79 80 #define GrayDitherPixel(dstX, dstY, pixel, red, green, blue) \ 81 do { \ 82 green = RGBTOGRAY(red, green, blue); \ 83 green += img_oda_gray[relx][rely]; \ 84 green = ComponentBound(green); \ 85 pixel = img_grays[img_bwgamma[green]]; \ 86 relx = (relx + 1) & 7; \ 87 } while (0) 88 89 #define GrayDitherBufComplete(cvdata, dstX1) \ 90 do {} while (0) 91