1 | #ifndef lint
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2 | static const char RCSid[] = "$Id: color.c,v 2.10 2003/02/25 02:47:21 greg Exp $";
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3 | #endif
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4 | /*
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5 | * color.c - routines for color calculations.
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6 | *
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7 | * Externals declared in color.h
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8 | */
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9 |
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10 | //#include "copyright.h"
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11 |
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12 | #include <stdio.h>
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13 |
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14 | #include <stdlib.h>
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15 |
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16 | #include <math.h>
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17 |
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18 | #include "color.h"
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19 |
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20 | #define MINELEN 8 /* minimum scanline length for encoding */
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21 | #define MAXELEN 0x7fff /* maximum scanline length for encoding */
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22 | #define MINRUN 4 /* minimum run length */
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23 |
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24 |
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25 | char *
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26 | tempbuffer(len) /* get a temporary buffer */
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27 | unsigned int len;
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28 | {
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29 | static char *tempbuf = NULL;
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30 | static unsigned tempbuflen = 0;
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31 |
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32 | if (len > tempbuflen) {
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33 | if (tempbuflen > 0)
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34 | tempbuf = (char *)realloc(tempbuf, len);
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35 | else
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36 | tempbuf = (char *)malloc(len);
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37 | tempbuflen = tempbuf==NULL ? 0 : len;
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38 | }
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39 | return(tempbuf);
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40 | }
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41 |
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42 |
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43 | int
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44 | fwritecolrs(scanline, len, fp) /* write out a colr scanline */
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45 | register COLR *scanline;
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46 | int len;
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47 | register FILE *fp;
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48 | {
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49 | register int i, j, beg, cnt = 1;
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50 | int c2;
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51 |
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52 | if (len < MINELEN | len > MAXELEN) /* OOBs, write out flat */
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53 | return(fwrite((char *)scanline,sizeof(COLR),len,fp) - len);
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54 | /* put magic header */
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55 | putc(2, fp);
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56 | putc(2, fp);
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57 | putc(len>>8, fp);
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58 | putc(len&255, fp);
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59 | /* put components seperately */
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60 | for (i = 0; i < 4; i++) {
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61 | for (j = 0; j < len; j += cnt) { /* find next run */
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62 | for (beg = j; beg < len; beg += cnt) {
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63 | for (cnt = 1; cnt < 127 && beg+cnt < len &&
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64 | scanline[beg+cnt][i] == scanline[beg][i]; cnt++)
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65 | ;
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66 | if (cnt >= MINRUN)
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67 | break; /* long enough */
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68 | }
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69 | if (beg-j > 1 && beg-j < MINRUN) {
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70 | c2 = j+1;
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71 | while (scanline[c2++][i] == scanline[j][i])
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72 | if (c2 == beg) { /* short run */
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73 | putc(128+beg-j, fp);
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74 | putc(scanline[j][i], fp);
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75 | j = beg;
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76 | break;
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77 | }
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78 | }
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79 | while (j < beg) { /* write out non-run */
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80 | if ((c2 = beg-j) > 128) c2 = 128;
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81 | putc(c2, fp);
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82 | while (c2--)
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83 | putc(scanline[j++][i], fp);
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84 | }
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85 | if (cnt >= MINRUN) { /* write out run */
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86 | putc(128+cnt, fp);
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87 | putc(scanline[beg][i], fp);
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88 | } else
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89 | cnt = 0;
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90 | }
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91 | }
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92 | return(ferror(fp) ? -1 : 0);
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93 | }
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94 |
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95 |
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96 | static int
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97 | oldreadcolrs(scanline, len, fp) /* read in an old colr scanline */
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98 | register COLR *scanline;
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99 | int len;
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100 | register FILE *fp;
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101 | {
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102 | int rshift;
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103 | register int i;
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104 |
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105 | rshift = 0;
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106 |
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107 | while (len > 0) {
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108 | scanline[0][RED] = getc(fp);
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109 | scanline[0][GRN] = getc(fp);
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110 | scanline[0][BLU] = getc(fp);
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111 | scanline[0][EXP] = getc(fp);
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112 | if (feof(fp) || ferror(fp))
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113 | return(-1);
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114 | if (scanline[0][RED] == 1 &&
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115 | scanline[0][GRN] == 1 &&
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116 | scanline[0][BLU] == 1) {
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117 | for (i = scanline[0][EXP] << rshift; i > 0; i--) {
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118 | copycolr(scanline[0], scanline[-1]);
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119 | scanline++;
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120 | len--;
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121 | }
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122 | rshift += 8;
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123 | } else {
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124 | scanline++;
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125 | len--;
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126 | rshift = 0;
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127 | }
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128 | }
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129 | return(0);
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130 | }
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131 |
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132 |
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133 | int
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134 | freadcolrs(scanline, len, fp) /* read in an encoded colr scanline */
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135 | register COLR *scanline;
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136 | int len;
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137 | register FILE *fp;
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138 | {
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139 | register int i, j;
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140 | int code, val;
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141 | /* determine scanline type */
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142 | if (len < MINELEN | len > MAXELEN)
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143 | return(oldreadcolrs(scanline, len, fp));
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144 | if ((i = getc(fp)) == EOF)
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145 | return(-1);
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146 | if (i != 2) {
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147 | ungetc(i, fp);
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148 | return(oldreadcolrs(scanline, len, fp));
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149 | }
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150 | scanline[0][GRN] = getc(fp);
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151 | scanline[0][BLU] = getc(fp);
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152 | if ((i = getc(fp)) == EOF)
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153 | return(-1);
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154 | if (scanline[0][GRN] != 2 || scanline[0][BLU] & 128) {
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155 | scanline[0][RED] = 2;
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156 | scanline[0][EXP] = i;
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157 | return(oldreadcolrs(scanline+1, len-1, fp));
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158 | }
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159 | if ((scanline[0][BLU]<<8 | i) != len)
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160 | return(-1); /* length mismatch! */
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161 | /* read each component */
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162 | for (i = 0; i < 4; i++)
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163 | for (j = 0; j < len; ) {
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164 | if ((code = getc(fp)) == EOF)
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165 | return(-1);
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166 | if (code > 128) { /* run */
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167 | code &= 127;
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168 | if ((val = getc(fp)) == EOF)
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169 | return -1;
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170 | while (code--)
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171 | scanline[j++][i] = val;
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172 | } else /* non-run */
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173 | while (code--) {
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174 | if ((val = getc(fp)) == EOF)
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175 | return -1;
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176 | scanline[j++][i] = val;
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177 | }
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178 | }
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179 | return(0);
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180 | }
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181 |
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182 |
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183 | int
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184 | fwritescan(scanline, len, fp) /* write out a scanline */
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185 | register COLOR *scanline;
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186 | int len;
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187 | FILE *fp;
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188 | {
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189 | COLR *clrscan;
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190 | int n;
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191 | register COLR *sp;
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192 | /* get scanline buffer */
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193 | if ((sp = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL)
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194 | return(-1);
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195 | clrscan = sp;
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196 | /* convert scanline */
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197 | n = len;
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198 | while (n-- > 0) {
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199 | setcolr(sp[0], scanline[0][RED],
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200 | scanline[0][GRN],
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201 | scanline[0][BLU]);
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202 | scanline++;
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203 | sp++;
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204 | }
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205 | return(fwritecolrs(clrscan, len, fp));
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206 | }
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207 |
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208 |
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209 | int
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210 | freadscan(scanline, len, fp) /* read in a scanline */
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211 | register COLOR *scanline;
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212 | int len;
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213 | FILE *fp;
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214 | {
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215 | register COLR *clrscan;
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216 |
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217 | if ((clrscan = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL)
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218 | return(-1);
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219 | if (freadcolrs(clrscan, len, fp) < 0)
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220 | return(-1);
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221 | /* convert scanline */
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222 | colr_color(scanline[0], clrscan[0]);
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223 | while (--len > 0) {
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224 | scanline++; clrscan++;
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225 | if (clrscan[0][RED] == clrscan[-1][RED] &&
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226 | clrscan[0][GRN] == clrscan[-1][GRN] &&
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227 | clrscan[0][BLU] == clrscan[-1][BLU] &&
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228 | clrscan[0][EXP] == clrscan[-1][EXP])
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229 | copycolor(scanline[0], scanline[-1]);
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230 | else
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231 | colr_color(scanline[0], clrscan[0]);
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232 | }
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233 | return(0);
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234 | }
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235 |
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236 |
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237 | void
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238 | setcolr(clr, r, g, b) /* assign a short color value */
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239 | register COLR clr;
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240 | double r, g, b;
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241 | {
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242 | double d;
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243 | int e;
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244 |
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245 | d = r > g ? r : g;
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246 | if (b > d) d = b;
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247 |
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248 | if (d <= 1e-32) {
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249 | clr[RED] = clr[GRN] = clr[BLU] = 0;
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250 | clr[EXP] = 0;
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251 | return;
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252 | }
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253 |
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254 | d = frexp(d, &e) * 255.9999 / d;
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255 |
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256 | clr[RED] = r * d;
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257 | clr[GRN] = g * d;
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258 | clr[BLU] = b * d;
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259 | clr[EXP] = e + COLXS;
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260 | }
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261 |
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262 |
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263 | void
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264 | colr_color(col, clr) /* convert short to float color */
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265 | register COLOR col;
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266 | register COLR clr;
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267 | {
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268 | double f;
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269 |
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270 | if (clr[EXP] == 0)
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271 | col[RED] = col[GRN] = col[BLU] = 0.0;
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272 | else {
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273 | f = ldexp(1.0, (int)clr[EXP]-(COLXS+8));
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274 | col[RED] = (clr[RED] + 0.5)*f;
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275 | col[GRN] = (clr[GRN] + 0.5)*f;
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276 | col[BLU] = (clr[BLU] + 0.5)*f;
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277 | }
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278 | }
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279 |
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280 |
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281 | int
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282 | bigdiff(c1, c2, md) /* c1 delta c2 > md? */
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283 | register COLOR c1, c2;
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284 | double md;
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285 | {
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286 | register int i;
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287 |
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288 | for (i = 0; i < 3; i++)
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289 | if (colval(c1,i)-colval(c2,i) > md*colval(c2,i) ||
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290 | colval(c2,i)-colval(c1,i) > md*colval(c1,i))
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291 | return(1);
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292 | return(0);
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293 | }
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