4.4BSD/usr/src/contrib/X11R5-lib/lib/X/TekHVCMxC.c
/* $XConsortium: TekHVCMxC.c,v 1.8 91/07/25 01:08:11 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. TekColor is a
* trademark of Tektronix, Inc. The term "TekHVC" designates a particular
* color space that is the subject of U.S. Patent No. 4,985,853 (equivalent
* foreign patents pending). 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:
*
* 1. This copyright, permission, and disclaimer notice is reproduced in
* all copies of this software and any modification thereof and in
* supporting documentation;
* 2. Any color-handling application which displays TekHVC color
* cooordinates identifies these as TekHVC color coordinates in any
* interface that displays these coordinates and in any associated
* documentation;
* 3. The term "TekHVC" is always used, and is only used, in association
* with the mathematical derivations of the TekHVC Color Space,
* including those provided in this file and any equivalent pathways and
* mathematical derivations, regardless of digital (e.g., floating point
* or integer) representation.
*
* 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
* TekHVCMxC.c
*
* DESCRIPTION
* Source for the XcmsTekHVCQueryMaxC() gamut boudary
* querying routine.
*
*/
#include "Xlibint.h"
#include "Xcmsint.h"
#include <math.h>
/*
* DEFINES
*/
#define MAXBISECTCOUNT 100
#define EPS 0.001
/*
* EXTERNS
*/
extern Status _XcmsTekHVCQueryMaxVCRGB();
extern int _XcmsTekHVC_CheckModify();
extern XcmsColorSpace XcmsTekHVCColorSpace;
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsTekHVCQueryMaxC - Compute the maximum chroma for a hue and value
*
* SYNOPSIS
*/
Status
XcmsTekHVCQueryMaxC(ccc, hue, value, pColor_return)
XcmsCCC ccc;
XcmsFloat hue;
XcmsFloat value;
XcmsColor *pColor_return;
/*
* DESCRIPTION
* Return the maximum chroma for a specific hue and value.
* The returned format is in XcmsTekHVCFormat.
*
*
* ASSUMPTIONS
* This routine assumes that the white point associated with
* the color specification is the Screen White Point. The
* Screen White Point will also be associated with the
* returned color specification.
*
* RETURNS
* XcmsFailure - Failure
* XcmsSuccess - Succeeded
*
*/
{
XcmsCCCRec myCCC;
XcmsColor tmp;
XcmsColor max_vc;
XcmsRGBi rgb_saved;
int nCount, nMaxCount;
XcmsFloat nValue, savedValue, lastValue, lastChroma, prevValue;
XcmsFloat maxDist, nT, rFactor;
XcmsFloat ftmp1, ftmp2;
/*
* Check Arguments
*/
if (ccc == NULL || pColor_return == NULL) {
return(XcmsFailure);
}
/*
* Insure TekHVC installed
*/
if (XcmsAddColorSpace(&XcmsTekHVCColorSpace) == XcmsFailure) {
return(XcmsFailure);
}
/* Use my own CCC */
bcopy ((char *)ccc, (char *)&myCCC, sizeof(XcmsCCCRec));
myCCC.clientWhitePt.format = XcmsUndefinedFormat; /* inherit screen white Pt */
myCCC.gamutCompProc = (XcmsCompressionProc)NULL;/* no gamut comp func */
tmp.spec.TekHVC.H = hue;
tmp.spec.TekHVC.V = value;
tmp.spec.TekHVC.C = 100.0;
tmp.pixel = pColor_return->pixel;
tmp.format = XcmsTekHVCFormat;
/* check to make sure we have a valid TekHVC number */
if (!_XcmsTekHVC_CheckModify(&tmp)) {
return(XcmsFailure);
}
/* Step 1: compute the maximum value and chroma for this hue. */
bcopy((char *)&tmp, (char *)&max_vc, sizeof(XcmsColor));
if (_XcmsTekHVCQueryMaxVCRGB(&myCCC, hue, &max_vc, &rgb_saved)
== XcmsFailure) {
return(XcmsFailure);
}
/* Step 2: If the value is less than the value for the maximum */
/* value, chroma point then the chroma is on the line */
/* from max_vc to 0,0. */
if (value <= max_vc.spec.TekHVC.V) {
tmp.spec.TekHVC.C = value
* max_vc.spec.TekHVC.C / max_vc.spec.TekHVC.V;
if (_XcmsTekHVC_CheckModify (&tmp)) {
bcopy((char *)&tmp, (char *)pColor_return, sizeof(XcmsColor));
return(XcmsSuccess);
} else {
return(XcmsFailure);
}
} else {
/* must do a bisection here to compute the maximum chroma */
/* save the structure input so that any elements that */
/* are not touched are recopied later in the routine. */
nValue = savedValue = value;
lastValue = -1.0;
nMaxCount = MAXBISECTCOUNT;
maxDist = 100.0 - max_vc.spec.TekHVC.V;
rFactor = 1.0;
for (nCount = 0; nCount < nMaxCount; nCount++) {
prevValue = lastValue;
lastValue = tmp.spec.TekHVC.V;
lastChroma = tmp.spec.TekHVC.C;
nT = (nValue - max_vc.spec.TekHVC.V) / maxDist * rFactor;
tmp.spec.RGBi.red = rgb_saved.red * (1.0 - nT) + nT;
tmp.spec.RGBi.green = rgb_saved.green * (1.0 - nT) + nT;
tmp.spec.RGBi.blue = rgb_saved.blue * (1.0 - nT) + nT;
tmp.format = XcmsRGBiFormat;
/* convert from RGB to HVC */
if (_XcmsConvertColorsWithWhitePt(&myCCC, &tmp,
&myCCC.pPerScrnInfo->screenWhitePt, 1, XcmsTekHVCFormat,
(Bool *) NULL) == XcmsFailure) {
return(XcmsFailure);
}
/* Now check the return against what is expected */
if (tmp.spec.TekHVC.V <= savedValue + EPS &&
tmp.spec.TekHVC.V >= savedValue - EPS) {
/* make sure to return the input hue */
tmp.spec.TekHVC.H = hue;
if (_XcmsTekHVC_CheckModify (&tmp)) {
bcopy((char *)&tmp, (char *)pColor_return, sizeof(XcmsColor));
return(XcmsSuccess);
} else {
return(XcmsFailure);
}
}
nValue += savedValue - tmp.spec.TekHVC.V;
if (nValue < max_vc.spec.TekHVC.V) {
nValue = max_vc.spec.TekHVC.V;
rFactor *= 0.5; /* selective relaxation employed */
} else if (nValue > 100.0) {
/* make sure to return the input hue */
tmp.spec.TekHVC.H = hue;
/* avoid using fabs */
ftmp1 = lastValue - savedValue;
if (ftmp1 < 0.0)
ftmp1 = -ftmp1;
ftmp2 = tmp.spec.TekHVC.V - savedValue;
if (ftmp2 < 0.0)
ftmp2 = -ftmp2;
if (ftmp1 < ftmp2) {
tmp.spec.TekHVC.V = lastValue;
tmp.spec.TekHVC.C = lastChroma;
}
if (_XcmsTekHVC_CheckModify (&tmp)) {
bcopy((char *)&tmp, (char *)pColor_return, sizeof(XcmsColor));
return(XcmsSuccess);
} else {
return(XcmsFailure);
}
} else if (tmp.spec.TekHVC.V <= prevValue + EPS &&
tmp.spec.TekHVC.V >= prevValue - EPS) {
rFactor *= 0.5; /* selective relaxation employed */
}
}
if (nCount >= nMaxCount) {
/* avoid using fabs */
ftmp1 = lastValue - savedValue;
if (ftmp1 < 0.0)
ftmp1 = -ftmp1;
ftmp2 = tmp.spec.TekHVC.V - savedValue;
if (ftmp2 < 0.0)
ftmp2 = -ftmp2;
if (ftmp1 < ftmp2) {
tmp.spec.TekHVC.V = lastValue;
tmp.spec.TekHVC.C = lastChroma;
}
}
}
/* make sure to return the input hue */
tmp.spec.TekHVC.H = hue;
bcopy((char *)&tmp, (char *)pColor_return, sizeof(XcmsColor));
return(XcmsSuccess);
}