4.4BSD/usr/src/contrib/X11R5-lib/lib/X/CIExyY.c
/* $XConsortium: CIExyY.c,v 1.7 91/07/25 01:07:54 rws Exp $" */
/*
* Code and supporting documentation (c) Copyright 1990 1991 Tektronix, Inc.
* All Rights Reserved
*
* This file is a component of an X Window System-specific implementation
* of Xcms based on the TekColor Color Management System. Permission is
* hereby granted to use, copy, modify, sell, and otherwise distribute this
* software and its documentation for any purpose and without fee, provided
* that this copyright, permission, and disclaimer notice is reproduced in
* all copies of this software and in supporting documentation. TekColor
* is a trademark of Tektronix, Inc.
*
* Tektronix makes no representation about the suitability of this software
* for any purpose. It is provided "as is" and with all faults.
*
* TEKTRONIX DISCLAIMS ALL WARRANTIES APPLICABLE TO THIS SOFTWARE,
* INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE. IN NO EVENT SHALL TEKTRONIX BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA, OR PROFITS, WHETHER IN AN ACTION OF
* CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR THE PERFORMANCE OF THIS SOFTWARE.
*
* NAME
* CIExyY.c
*
* DESCRIPTION
* This file contains routines that support the CIE xyY
* color space to include conversions to and from the CIE
* XYZ space.
*
* DOCUMENTATION
* "TekColor Color Management System, System Implementor's Manual"
*/
#include <stdio.h>
#include <X11/Xos.h>
#include "Xlibint.h"
#include "Xcmsint.h"
/*
* DEFINES
*/
#define EPS 0.00001 /* some extremely small number */
#ifdef DBL_EPSILON
# define XMY_DBL_EPSILON DBL_EPSILON
#else
# define XMY_DBL_EPSILON 0.00001
#endif
/*
* EXTERNS
*/
extern char XcmsCIExyY_prefix[];
/*
* FORWARD DECLARATIONS
*/
static int CIExyY_ParseString();
Status XcmsCIExyY_ValidSpec();
/*
* LOCAL VARIABLES
*/
/*
* NULL terminated list of functions applied to get from CIExyY to CIEXYZ
*/
static XcmsConversionProc Fl_CIExyY_to_CIEXYZ[] = {
XcmsCIExyYToCIEXYZ,
NULL
};
/*
* NULL terminated list of functions applied to get from CIEXYZ to CIExyY
*/
static XcmsConversionProc Fl_CIEXYZ_to_CIExyY[] = {
XcmsCIEXYZToCIExyY,
NULL
};
/*
* GLOBALS
*/
/*
* CIE xyY Color Space
*/
XcmsColorSpace XcmsCIExyYColorSpace =
{
XcmsCIExyY_prefix, /* prefix */
XcmsCIExyYFormat, /* id */
CIExyY_ParseString, /* parseString */
Fl_CIExyY_to_CIEXYZ, /* to_CIEXYZ */
Fl_CIEXYZ_to_CIExyY, /* from_CIEXYZ */
1
};
/************************************************************************
* *
* PRIVATE ROUTINES *
* *
************************************************************************/
/*
* NAME
* CIExyY_ParseString
*
* SYNOPSIS
*/
static int
CIExyY_ParseString(spec, pColor)
register char *spec;
XcmsColor *pColor;
/*
* DESCRIPTION
* This routines takes a string and attempts to convert
* it into a XcmsColor structure with XcmsCIExyYFormat.
* The assumed CIExyY string syntax is:
* CIExyY:<x>/<y>/<Y>
* Where x, y, and Y are in string input format for floats
* consisting of:
* a. an optional sign
* b. a string of numbers possibly containing a decimal point,
* c. an optional exponent field containing an 'E' or 'e'
* followed by a possibly signed integer string.
*
* RETURNS
* 0 if failed, non-zero otherwise.
*/
{
int n;
char *pchar;
if ((pchar = strchr(spec, ':')) == NULL) {
return(XcmsFailure);
}
n = (int)(pchar - spec);
/*
* Check for proper prefix.
*/
if (strncmp(spec, XcmsCIExyY_prefix, n) != 0) {
return(XcmsFailure);
}
/*
* Attempt to parse the value portion.
*/
if (sscanf(spec + n + 1, "%lf/%lf/%lf",
&pColor->spec.CIExyY.x,
&pColor->spec.CIExyY.y,
&pColor->spec.CIExyY.Y) != 3) {
return(XcmsFailure);
}
pColor->format = XcmsCIExyYFormat;
pColor->pixel = 0;
return(XcmsCIExyY_ValidSpec(pColor));
}
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* CIExyY_ValidSpec()
*
* SYNOPSIS
*/
Status
XcmsCIExyY_ValidSpec(pColor)
XcmsColor *pColor;
/*
* DESCRIPTION
* Checks a valid CIExyY color specification.
*
* RETURNS
* XcmsFailure if invalid.
* XcmsSuccess if valid.
*
*/
{
if (pColor->format != XcmsCIExyYFormat
||
(pColor->spec.CIExyY.x < 0.0 - XMY_DBL_EPSILON)
||
(pColor->spec.CIExyY.x > 1.0 + XMY_DBL_EPSILON)
||
(pColor->spec.CIExyY.y < 0.0 - XMY_DBL_EPSILON)
||
(pColor->spec.CIExyY.y > 1.0 + XMY_DBL_EPSILON)
||
(pColor->spec.CIExyY.Y < 0.0 - XMY_DBL_EPSILON)
||
(pColor->spec.CIExyY.Y > 1.0 + XMY_DBL_EPSILON)) {
return(XcmsFailure);
}
return(XcmsSuccess);
}
/*
* NAME
* XcmsCIExyYToCIEXYZ - convert CIExyY to CIEXYZ
*
* SYNOPSIS
*/
Status
XcmsCIExyYToCIEXYZ(ccc, pxyY_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *pxyY_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Converts color specifications in an array of XcmsColor
* structures from CIExyY format to CIEXYZ format.
*
* RETURNS
* XcmsFailure if failed,
* XcmsSuccess if succeeded.
*/
{
XcmsColor *pColor = pColors_in_out;
XcmsColor whitePt;
XcmsCIEXYZ XYZ_return;
XcmsFloat div; /* temporary storage in case divisor is zero */
XcmsFloat u, v, x, y, z; /* temporary storage */
register int i;
/*
* Check arguments
*/
if (pxyY_WhitePt == NULL || pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEXYZ form
*/
for (i = 0; i < nColors; i++, pColor++) {
/* Make sure original format is CIExyY and valid */
if (!XcmsCIExyY_ValidSpec(pColor)) {
return(XcmsFailure);
}
if ((div = (-2 * pColor->spec.CIExyY.x) + (12 * pColor->spec.CIExyY.y) + 3) == 0.0) {
/* Note that the divisor is zero */
/* This return is abitrary. */
XYZ_return.X = 0;
XYZ_return.Y = 0;
XYZ_return.Z = 0;
} else {
/*
* Make sure white point is in CIEXYZ form
*/
if (pxyY_WhitePt->format != XcmsCIEXYZFormat) {
/* Make copy of the white point because we're going to modify it */
bcopy((char *)pxyY_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
XcmsCIEXYZFormat)) {
return(XcmsFailure);
}
pxyY_WhitePt = &whitePt;
}
/* Make sure it is a white point, i.e., Y == 1.0 */
if (pxyY_WhitePt->spec.CIEXYZ.Y != 1.0) {
return(XcmsFailure);
}
/* Convert from xyY to uvY to XYZ */
u = (4 * pColor->spec.CIExyY.x) / div;
v = (9 * pColor->spec.CIExyY.y) / div;
div = (6.0 * u) - (16.0 * v) + 12.0;
if (div == 0.0) {
/* Note that the divisor is zero */
/* This return is abitrary. */
if ((div = (6.0 * whitePt.spec.CIEuvY.u_prime) -
(16.0 * whitePt.spec.CIEuvY.v_prime) + 12.0) == 0.0) {
div = EPS;
}
x = 9.0 * whitePt.spec.CIEuvY.u_prime / div;
y = 4.0 * whitePt.spec.CIEuvY.u_prime / div;
} else {
/* convert u, v to small xyz */
x = 9.0 * u / div;
y = 4.0 * v / div;
}
z = 1.0 - x - y;
if (y == 0.0) y = EPS; /* Have to worry about divide by 0 */
XYZ_return.Y = pColor->spec.CIExyY.Y;
XYZ_return.X = x * XYZ_return.Y / y;
XYZ_return.Z = z * XYZ_return.Y / y;
}
/* Copy result to pColor */
bcopy ((char *)&XYZ_return, (char *)&pColor->spec, sizeof(XcmsCIEXYZ));
/* Identify that the format is now CIEXYZ */
pColor->format = XcmsCIEXYZFormat;
}
return(XcmsSuccess);
}
/*
* NAME
* XcmsCIEXYZToCIExyY - convert CIEXYZ to CIExyY
*
* SYNOPSIS
*/
/* ARGSUSED */
Status
XcmsCIEXYZToCIExyY(ccc, pxyY_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *pxyY_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Converts color specifications in an array of XcmsColor
* structures from CIEXYZ format to CIExyY format.
*
* RETURNS
* XcmsFailure if failed,
* XcmsSuccess if succeeded.
*
*/
{
XcmsColor *pColor = pColors_in_out;
XcmsCIExyY xyY_return;
XcmsFloat div; /* temporary storage in case divisor is zero */
register int i;
/*
* Check arguments
* pxyY_WhitePt ignored
*/
if (pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEXYZ form
*/
for (i = 0; i < nColors; i++, pColor++) {
if (!XcmsCIEXYZ_ValidSpec(pColor)) {
return(XcmsFailure);
}
/* Now convert for XYZ to xyY */
if ((div = pColor->spec.CIEXYZ.X + pColor->spec.CIEXYZ.Y + pColor->spec.CIEXYZ.Z) == 0.0) {
div = EPS;
}
xyY_return.x = pColor->spec.CIEXYZ.X / div;
xyY_return.y = pColor->spec.CIEXYZ.Y / div;
xyY_return.Y = pColor->spec.CIEXYZ.Y;
/* Copy result to pColor */
bcopy ((char *)&xyY_return, (char *)&pColor->spec, sizeof(XcmsCIExyY));
/* Identify that the format is now CIEXYZ */
pColor->format = XcmsCIExyYFormat;
}
return(XcmsSuccess);
}