1 /* 2 * Copyright (c) 1996, 1998, 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 implements some of the standard utility procedures used 28 * by the image conversion package. 29 */ 30 31 #include "img_globals.h" 32 33 #include "java_awt_image_IndexColorModel.h" 34 #include "java_awt_image_DirectColorModel.h" 35 #include "java_awt_Transparency.h" 36 37 /* 38 * This function constructs an 8x8 ordered dither array which can be 39 * used to dither data into an output range with discreet values that 40 * differ by the value specified as quantum. A monochrome screen would 41 * use a dither array constructed with the quantum 256. 42 * The array values produced are unsigned and intended to be used with 43 * a lookup table which returns the next color darker than the error 44 * adjusted color used as the index. 45 */ 46 void 47 make_uns_ordered_dither_array(uns_ordered_dither_array oda, 48 int quantum) 49 { 50 int i, j, k; 51 52 oda[0][0] = 0; 53 for (k = 1; k < 8; k *= 2) { 54 for (i = 0; i < k; i++) { 55 for (j = 0; j < k; j++) { 56 oda[ i ][ j ] = oda[i][j] * 4; 57 oda[i+k][j+k] = oda[i][j] + 1; 58 oda[ i ][j+k] = oda[i][j] + 2; 59 oda[i+k][ j ] = oda[i][j] + 3; 60 } 61 } 62 } 63 for (i = 0; i < 8; i++) { 64 for (j = 0; j < 8; j++) { 65 oda[i][j] = oda[i][j] * quantum / 64; 66 } 67 } 68 } 69 70 /* 71 * This function constructs an 8x8 ordered dither array which can be 72 * used to dither data into an output range with discreet values that 73 * are distributed over the range from minerr to maxerr around a given 74 * target color value. 75 * The array values produced are signed and intended to be used with 76 * a lookup table which returns the closest color to the error adjusted 77 * color used as an index. 78 */ 79 void 80 make_sgn_ordered_dither_array(char* oda, int minerr, int maxerr) 81 { 82 int i, j, k; 83 84 oda[0] = 0; 85 for (k = 1; k < 8; k *= 2) { 86 for (i = 0; i < k; i++) { 87 for (j = 0; j < k; j++) { 88 oda[(i<<3) + j] = oda[(i<<3)+j] * 4; 89 oda[((i+k)<<3) + j+k] = oda[(i<<3)+j] + 1; 90 oda[(i<<3) + j+k] = oda[(i<<3)+j] + 2; 91 oda[((i+k)<<3) + j] = oda[(i<<3)+j] + 3; 92 } 93 } 94 } 95 k = 0; 96 for (i = 0; i < 8; i++) { 97 for (j = 0; j < 8; j++) { 98 oda[k] = oda[k] * (maxerr - minerr) / 64 + minerr; 99 k++; 100 } 101 } 102 } 103 104 #ifdef TESTING 105 #include <stdio.h> 106 107 /* Function to test the ordered dither error matrix initialization function. */ 108 main(int argc, char **argv) 109 { 110 int i, j; 111 int quantum; 112 int max, val; 113 uns_ordered_dither_array oda; 114 115 if (argc > 1) { 116 quantum = atoi(argv[1]); 117 } else { 118 quantum = 64; 119 } 120 make_uns_ordered_dither_array(oda, quantum); 121 for (i = 0; i < 8; i++) { 122 for (j = 0; j < 8; j++) { 123 val = oda[i][j]; 124 printf("%4d", val); 125 if (max < val) { 126 max = val; 127 } 128 } 129 printf("\n"); 130 } 131 printf("\nmax = %d\n", max); 132 } 133 #endif /* TESTING */