src/common/color.c

/* Copyright (c) 1991 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  color.c - routines for color calculations.
 *
 *     10/10/85
 */

#include  <stdio.h>

#include  "color.h"

#define  MINELEN        8       /* minimum scanline length for encoding */
#define  MINRUN         4       /* minimum run length */


char *
tempbuffer(len)                 /* get a temporary buffer */
unsigned  len;
{
        extern char  *malloc(), *realloc();
        static char  *tempbuf = NULL;
        static int  tempbuflen = 0;

        if (len > tempbuflen) {
                if (tempbuflen > 0)
                        tempbuf = realloc(tempbuf, len);
                else
                        tempbuf = malloc(len);
                tempbuflen = tempbuf==NULL ? 0 : len;
        }
        return(tempbuf);
}


fwritecolrs(scanline, len, fp)          /* write out a colr scanline */
register COLR  *scanline;
int  len;
register FILE  *fp;
{
        register int  i, j, beg, cnt;
        int  c2;
        
        if (len < MINELEN)              /* too small to encode */
                return(fwrite((char *)scanline,sizeof(COLR),len,fp) - len);
        if (len > 32767)                /* too big! */
                return(-1);
        putc(2, fp);                    /* put magic header */
        putc(2, fp);
        putc(len>>8, fp);
        putc(len&255, fp);
                                        /* put components seperately */
        for (i = 0; i < 4; i++) {
            for (j = 0; j < len; j += cnt) {    /* find next run */
                for (beg = j; beg < len; beg += cnt) {
                    for (cnt = 1; cnt < 127 && beg+cnt < len &&
                            scanline[beg+cnt][i] == scanline[beg][i]; cnt++)
                        ;
                    if (cnt >= MINRUN)
                        break;                  /* long enough */
                }
                if (beg-j > 1 && beg-j < MINRUN) {
                    c2 = j+1;
                    while (scanline[c2++][i] == scanline[j][i])
                        if (c2 == beg) {        /* short run */
                            putc(128+beg-j, fp);
                            putc(scanline[j][i], fp);
                            j = beg;
                            break;
                        }
                }
                while (j < beg) {               /* write out non-run */
                    if ((c2 = beg-j) > 128) c2 = 128;
                    putc(c2, fp);
                    while (c2--)
                        putc(scanline[j++][i], fp);
                }
                if (cnt >= MINRUN) {            /* write out run */
                    putc(128+cnt, fp);
                    putc(scanline[beg][i], fp);
                } else
                    cnt = 0;
            }
        }
        return(ferror(fp) ? -1 : 0);
}


freadcolrs(scanline, len, fp)           /* read in an encoded colr scanline */
register COLR  *scanline;
int  len;
register FILE  *fp;
{
        register int  i, j;
        int  code;
                                        /* determine scanline type */
        if (len < MINELEN)
                return(oldreadcolrs(scanline, len, fp));
        if ((i = getc(fp)) == EOF)
                return(-1);
        if (i != 2) {
                ungetc(i, fp);
                return(oldreadcolrs(scanline, len, fp));
        }
        scanline[0][GRN] = getc(fp);
        scanline[0][BLU] = getc(fp);
        if ((i = getc(fp)) == EOF)
                return(-1);
        if (scanline[0][GRN] != 2 || scanline[0][BLU] & 128) {
                scanline[0][RED] = 2;
                scanline[0][EXP] = i;
                return(oldreadcolrs(scanline+1, len-1, fp));
        }
        if ((scanline[0][BLU]<<8 | i) != len)
                return(-1);             /* length mismatch! */
                                        /* read each component */
        for (i = 0; i < 4; i++)
            for (j = 0; j < len; ) {
                if ((code = getc(fp)) == EOF)
                    return(-1);
                if (code > 128) {       /* run */
                    scanline[j++][i] = getc(fp);
                    for (code &= 127; --code; j++)
                        scanline[j][i] = scanline[j-1][i];
                } else                  /* non-run */
                    while (code--)
                        scanline[j++][i] = getc(fp);
            }
        return(feof(fp) ? -1 : 0);
}


oldreadcolrs(scanline, len, fp)         /* read in an old colr scanline */
register COLR  *scanline;
int  len;
register FILE  *fp;
{
        int  rshift;
        register int  i;
        
        rshift = 0;
        
        while (len > 0) {
                scanline[0][RED] = getc(fp);
                scanline[0][GRN] = getc(fp);
                scanline[0][BLU] = getc(fp);
                scanline[0][EXP] = getc(fp);
                if (feof(fp) || ferror(fp))
                        return(-1);
                if (scanline[0][RED] == 1 &&
                                scanline[0][GRN] == 1 &&
                                scanline[0][BLU] == 1) {
                        for (i = scanline[0][EXP] << rshift; i > 0; i--) {
                                copycolr(scanline[0], scanline[-1]);
                                scanline++;
                                len--;
                        }
                        rshift += 8;
                } else {
                        scanline++;
                        len--;
                        rshift = 0;
                }
        }
        return(0);
}


fwritescan(scanline, len, fp)           /* write out a scanline */
register COLOR  *scanline;
int  len;
FILE  *fp;
{
        COLR  *clrscan;
        int  n;
        register COLR  *sp;
                                        /* get scanline buffer */
        if ((sp = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL)
                return(-1);
        clrscan = sp;
                                        /* convert scanline */
        n = len;
        while (n-- > 0) {
                setcolr(sp[0], scanline[0][RED],
                                  scanline[0][GRN],
                                  scanline[0][BLU]);
                scanline++;
                sp++;
        }
        return(fwritecolrs(clrscan, len, fp));
}


freadscan(scanline, len, fp)            /* read in a scanline */
register COLOR  *scanline;
int  len;
FILE  *fp;
{
        register COLR  *clrscan;

        if ((clrscan = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL)
                return(-1);
        if (freadcolrs(clrscan, len, fp) < 0)
                return(-1);
                                        /* convert scanline */
        colr_color(scanline[0], clrscan[0]);
        while (--len > 0) {
                scanline++; clrscan++;
                if (clrscan[0][RED] == clrscan[-1][RED] &&
                            clrscan[0][GRN] == clrscan[-1][GRN] &&
                            clrscan[0][BLU] == clrscan[-1][BLU] &&
                            clrscan[0][EXP] == clrscan[-1][EXP])
                        copycolor(scanline[0], scanline[-1]);
                else
                        colr_color(scanline[0], clrscan[0]);
        }
        return(0);
}


setcolr(clr, r, g, b)           /* assign a short color value */
register COLR  clr;
double  r, g, b;
{
        double  frexp();
        double  d;
        int  e;
        
        d = r > g ? r : g;
        if (b > d) d = b;

        if (d <= 1e-32) {
                clr[RED] = clr[GRN] = clr[BLU] = 0;
                clr[EXP] = 0;
                return;
        }

        d = frexp(d, &e) * 256.0 / d;

        clr[RED] = r * d;
        clr[GRN] = g * d;
        clr[BLU] = b * d;
        clr[EXP] = e + COLXS;
}


colr_color(col, clr)            /* convert short to float color */
register COLOR  col;
register COLR  clr;
{
        double  f;
        
        if (clr[EXP] == 0)
                col[RED] = col[GRN] = col[BLU] = 0.0;
        else {
                f = ldexp(1.0, (int)clr[EXP]-(COLXS+8));
                col[RED] = (clr[RED] + 0.5)*f;
                col[GRN] = (clr[GRN] + 0.5)*f;
                col[BLU] = (clr[BLU] + 0.5)*f;
        }
}


bigdiff(c1, c2, md)                     /* c1 delta c2 > md? */
register COLOR  c1, c2;
double  md;
{
        register int  i;

        for (i = 0; i < 3; i++)
                if (colval(c1,i)-colval(c2,i) > md*colval(c2,i) ||
                        colval(c2,i)-colval(c1,i) > md*colval(c1,i))
                        return(1);
        return(0);
}
Revision:	1.15
Committed:	Wed Aug 28 08:39:47 1991 UTC (32 years, 8 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.14:	+11 -1 lines
Log Message:	slight improvement to run-length encoding
#	User	Rev	Content
1	greg	1.14	/* Copyright (c) 1991 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* color.c - routines for color calculations.
9			*
10			* 10/10/85
11			*/
12
13			#include <stdio.h>
14
15			#include "color.h"
16
17	greg	1.14	#define MINELEN 8 /* minimum scanline length for encoding */
18			#define MINRUN 4 /* minimum run length */
19	greg	1.5
20	greg	1.14
21			char *
22			tempbuffer(len) /* get a temporary buffer */
23			unsigned len;
24			{
25			extern char malloc(), realloc();
26			static char *tempbuf = NULL;
27			static int tempbuflen = 0;
28
29			if (len > tempbuflen) {
30			if (tempbuflen > 0)
31			tempbuf = realloc(tempbuf, len);
32			else
33			tempbuf = malloc(len);
34			tempbuflen = tempbuf==NULL ? 0 : len;
35			}
36			return(tempbuf);
37			}
38
39
40	greg	1.1	fwritecolrs(scanline, len, fp) /* write out a colr scanline */
41			register COLR *scanline;
42			int len;
43			register FILE *fp;
44			{
45	greg	1.14	register int i, j, beg, cnt;
46			int c2;
47	greg	1.1
48	greg	1.14	if (len < MINELEN) /* too small to encode */
49			return(fwrite((char *)scanline,sizeof(COLR),len,fp) - len);
50			if (len > 32767) /* too big! */
51			return(-1);
52			putc(2, fp); /* put magic header */
53			putc(2, fp);
54			putc(len>>8, fp);
55			putc(len&255, fp);
56			/* put components seperately */
57			for (i = 0; i < 4; i++) {
58			for (j = 0; j < len; j += cnt) { /* find next run */
59			for (beg = j; beg < len; beg += cnt) {
60			for (cnt = 1; cnt < 127 && beg+cnt < len &&
61			scanline[beg+cnt][i] == scanline[beg][i]; cnt++)
62			;
63			if (cnt >= MINRUN)
64			break; /* long enough */
65	greg	1.1	}
66	greg	1.15	if (beg-j > 1 && beg-j < MINRUN) {
67			c2 = j+1;
68			while (scanline[c2++][i] == scanline[j][i])
69			if (c2 == beg) { /* short run */
70			putc(128+beg-j, fp);
71			putc(scanline[j][i], fp);
72			j = beg;
73			break;
74			}
75			}
76			while (j < beg) { /* write out non-run */
77	greg	1.14	if ((c2 = beg-j) > 128) c2 = 128;
78			putc(c2, fp);
79			while (c2--)
80			putc(scanline[j++][i], fp);
81			}
82			if (cnt >= MINRUN) { /* write out run */
83			putc(128+cnt, fp);
84			putc(scanline[beg][i], fp);
85			} else
86			cnt = 0;
87			}
88	greg	1.1	}
89			return(ferror(fp) ? -1 : 0);
90			}
91
92
93	greg	1.14	freadcolrs(scanline, len, fp) /* read in an encoded colr scanline */
94	greg	1.1	register COLR *scanline;
95			int len;
96			register FILE *fp;
97			{
98	greg	1.14	register int i, j;
99			int code;
100			/* determine scanline type */
101			if (len < MINELEN)
102			return(oldreadcolrs(scanline, len, fp));
103			if ((i = getc(fp)) == EOF)
104			return(-1);
105			if (i != 2) {
106			ungetc(i, fp);
107			return(oldreadcolrs(scanline, len, fp));
108			}
109			scanline[0][GRN] = getc(fp);
110			scanline[0][BLU] = getc(fp);
111			if ((i = getc(fp)) == EOF)
112			return(-1);
113			if (scanline[0][GRN] != 2 \|\| scanline[0][BLU] & 128) {
114			scanline[0][RED] = 2;
115			scanline[0][EXP] = i;
116			return(oldreadcolrs(scanline+1, len-1, fp));
117			}
118			if ((scanline[0][BLU]<<8 \| i) != len)
119			return(-1); /* length mismatch! */
120			/* read each component */
121			for (i = 0; i < 4; i++)
122			for (j = 0; j < len; ) {
123			if ((code = getc(fp)) == EOF)
124			return(-1);
125			if (code > 128) { /* run */
126			scanline[j++][i] = getc(fp);
127			for (code &= 127; --code; j++)
128			scanline[j][i] = scanline[j-1][i];
129			} else /* non-run */
130			while (code--)
131			scanline[j++][i] = getc(fp);
132			}
133			return(feof(fp) ? -1 : 0);
134			}
135
136
137			oldreadcolrs(scanline, len, fp) /* read in an old colr scanline */
138			register COLR *scanline;
139			int len;
140			register FILE *fp;
141			{
142	greg	1.1	int rshift;
143			register int i;
144
145			rshift = 0;
146
147			while (len > 0) {
148			scanline[0][RED] = getc(fp);
149			scanline[0][GRN] = getc(fp);
150			scanline[0][BLU] = getc(fp);
151			scanline[0][EXP] = getc(fp);
152			if (feof(fp) \|\| ferror(fp))
153			return(-1);
154			if (scanline[0][RED] == 1 &&
155			scanline[0][GRN] == 1 &&
156			scanline[0][BLU] == 1) {
157			for (i = scanline[0][EXP] << rshift; i > 0; i--) {
158			copycolr(scanline[0], scanline[-1]);
159			scanline++;
160			len--;
161			}
162			rshift += 8;
163			} else {
164			scanline++;
165			len--;
166			rshift = 0;
167			}
168			}
169			return(0);
170			}
171
172
173			fwritescan(scanline, len, fp) /* write out a scanline */
174			register COLOR *scanline;
175			int len;
176	greg	1.14	FILE *fp;
177	greg	1.1	{
178	greg	1.14	COLR *clrscan;
179			int n;
180			register COLR *sp;
181			/* get scanline buffer */
182			if ((sp = (COLR )tempbuffer(lensizeof(COLR))) == NULL)
183			return(-1);
184			clrscan = sp;
185			/* convert scanline */
186			n = len;
187			while (n-- > 0) {
188			setcolr(sp[0], scanline[0][RED],
189	greg	1.1	scanline[0][GRN],
190			scanline[0][BLU]);
191			scanline++;
192	greg	1.14	sp++;
193	greg	1.1	}
194	greg	1.14	return(fwritecolrs(clrscan, len, fp));
195	greg	1.1	}
196
197
198			freadscan(scanline, len, fp) /* read in a scanline */
199			register COLOR *scanline;
200			int len;
201	greg	1.14	FILE *fp;
202	greg	1.1	{
203	greg	1.14	register COLR *clrscan;
204
205			if ((clrscan = (COLR )tempbuffer(lensizeof(COLR))) == NULL)
206			return(-1);
207			if (freadcolrs(clrscan, len, fp) < 0)
208			return(-1);
209			/* convert scanline */
210			colr_color(scanline[0], clrscan[0]);
211			while (--len > 0) {
212			scanline++; clrscan++;
213			if (clrscan[0][RED] == clrscan[-1][RED] &&
214			clrscan[0][GRN] == clrscan[-1][GRN] &&
215			clrscan[0][BLU] == clrscan[-1][BLU] &&
216			clrscan[0][EXP] == clrscan[-1][EXP])
217			copycolor(scanline[0], scanline[-1]);
218			else
219			colr_color(scanline[0], clrscan[0]);
220	greg	1.1	}
221			return(0);
222			}
223
224
225			setcolr(clr, r, g, b) /* assign a short color value */
226			register COLR clr;
227			double r, g, b;
228			{
229			double frexp();
230			double d;
231			int e;
232
233			d = r > g ? r : g;
234			if (b > d) d = b;
235
236	greg	1.4	if (d <= 1e-32) {
237	greg	1.1	clr[RED] = clr[GRN] = clr[BLU] = 0;
238			clr[EXP] = 0;
239			return;
240			}
241
242			d = frexp(d, &e) * 256.0 / d;
243
244			clr[RED] = r * d;
245			clr[GRN] = g * d;
246			clr[BLU] = b * d;
247			clr[EXP] = e + COLXS;
248			}
249
250
251			colr_color(col, clr) /* convert short to float color */
252			register COLOR col;
253			register COLR clr;
254			{
255	greg	1.6	double f;
256	greg	1.1
257			if (clr[EXP] == 0)
258			col[RED] = col[GRN] = col[BLU] = 0.0;
259			else {
260	greg	1.2	f = ldexp(1.0, (int)clr[EXP]-(COLXS+8));
261	greg	1.1	col[RED] = (clr[RED] + 0.5)*f;
262			col[GRN] = (clr[GRN] + 0.5)*f;
263			col[BLU] = (clr[BLU] + 0.5)*f;
264			}
265	greg	1.6	}
266
267
268	greg	1.7	bigdiff(c1, c2, md) /* c1 delta c2 > md? */
269			register COLOR c1, c2;
270			double md;
271			{
272			register int i;
273
274			for (i = 0; i < 3; i++)
275			if (colval(c1,i)-colval(c2,i) > md*colval(c2,i) \|\|
276			colval(c2,i)-colval(c1,i) > md*colval(c1,i))
277			return(1);
278			return(0);
279			}