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/*
* 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
* TekHVCMxV.c
*
* DESCRIPTION
* Source for the XcmsTekHVCQueryMaxV() gamut boundary
* querying routine.
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "Xlibint.h"
#include "Xcmsint.h"
#include <math.h>
#include "Cv.h"
/*
* DEFINES
*/
#define MAXBISECTCOUNT 100
#define EPS 0.001
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsTekHVCQueryMaxV - Compute maximum value for a hue and chroma
*
* SYNOPSIS
*/
Status
XcmsTekHVCQueryMaxV(
XcmsCCC ccc,
XcmsFloat hue,
XcmsFloat chroma,
XcmsColor *pColor_return)
/*
* DESCRIPTION
* Return the maximum value for a specified hue and chroma.
*
* 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 with no modifications
*
*/
{
XcmsCCCRec myCCC;
XcmsColor tmp;
XcmsColor max_vc;
XcmsRGBi rgb_saved;
int nCount, nMaxCount;
XcmsFloat nT, nChroma, savedChroma, lastValue, lastChroma, prevChroma;
XcmsFloat rFactor;
XcmsFloat ftmp1, ftmp2;
/*
* Check Arguments
*/
if (ccc == NULL || pColor_return == NULL) {
return(XcmsFailure);
}
/*
* Insure TekHVC installed
*/
if (XcmsAddColorSpace(&XcmsTekHVCColorSpace) == XcmsFailure) {
return(XcmsFailure);
}
/* setup the CCC to use for the conversions. */
memcpy ((char *) &myCCC, (char *) ccc, sizeof(XcmsCCCRec));
myCCC.clientWhitePt.format = XcmsUndefinedFormat;
myCCC.gamutCompProc = (XcmsCompressionProc) NULL;
tmp.spec.TekHVC.H = hue;
tmp.spec.TekHVC.V = 0.0;
tmp.spec.TekHVC.C = chroma;
tmp.pixel = pColor_return->pixel;
tmp.format = XcmsTekHVCFormat;
if (!_XcmsTekHVC_CheckModify (&tmp)) {
return(XcmsFailure);
}
/* Step 1: compute the maximum value and chroma for this hue. */
/* This copy may be overkill but it preserves the pixel etc. */
memcpy((char *)&max_vc, (char *)&tmp, sizeof(XcmsColor));
hue = max_vc.spec.TekHVC.H;
if (_XcmsTekHVCQueryMaxVCRGB(&myCCC, max_vc.spec.TekHVC.H, &max_vc, &rgb_saved)
== XcmsFailure) {
return(XcmsFailure);
}
if (max_vc.spec.TekHVC.C < tmp.spec.TekHVC.C) {
/*
* If the chroma is greater than the chroma for the
* maximum value/chroma point then the value is the
* the value for the maximum value, chroma point.
* This is an error but it I return the best approximation I can.
* Thus the inconsistency.
*/
tmp.spec.TekHVC.C = max_vc.spec.TekHVC.C;
tmp.spec.TekHVC.V = max_vc.spec.TekHVC.V;
memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
return(XcmsSuccess);
} else if (max_vc.spec.TekHVC.C == tmp.spec.TekHVC.C) {
/*
* If the chroma is equal to the chroma for the
* maximum value/chroma point then the value is the
* the value for the maximum value, chroma point.
*/
tmp.spec.TekHVC.V = max_vc.spec.TekHVC.V;
memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
return(XcmsSuccess);
} else {
/* must do a bisection here to compute the maximum value */
/* save the structure input so that any elements that */
/* are not touched are recopied later in the routine. */
nChroma = savedChroma = tmp.spec.TekHVC.C;
tmp.spec.TekHVC.C = max_vc.spec.TekHVC.C;
tmp.spec.TekHVC.V = max_vc.spec.TekHVC.V;
lastChroma = -1.0;
lastValue = -1.0;
nMaxCount = MAXBISECTCOUNT;
rFactor = 1.0;
for (nCount = 0; nCount < nMaxCount; nCount++) {
prevChroma = lastChroma;
lastValue = tmp.spec.TekHVC.V;
lastChroma = tmp.spec.TekHVC.C;
nT = (1.0 - (nChroma / max_vc.spec.TekHVC.C)) * 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.C <= savedChroma + EPS &&
tmp.spec.TekHVC.C >= savedChroma - EPS) {
tmp.spec.TekHVC.H = hue; /* use the saved hue */
memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
return(XcmsSuccess);
}
nChroma += savedChroma - tmp.spec.TekHVC.C;
if (nChroma > max_vc.spec.TekHVC.C) {
nChroma = max_vc.spec.TekHVC.C;
rFactor *= 0.5; /* selective relaxation employed */
} else if (nChroma < 0.0) {
/* avoid using fabs */
ftmp1 = lastChroma - savedChroma;
if (ftmp1 < 0.0)
ftmp1 = -ftmp1;
ftmp2 = tmp.spec.TekHVC.C - savedChroma;
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;
if (!_XcmsTekHVC_CheckModify(&tmp)) {
return(XcmsFailure);
}
memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
return(XcmsSuccess);
} else if (tmp.spec.TekHVC.C <= prevChroma + EPS &&
tmp.spec.TekHVC.C >= prevChroma - EPS) {
rFactor *= 0.5; /* selective relaxation employed */
}
}
if (nCount >= nMaxCount) {
/* avoid using fabs */
ftmp1 = lastChroma - savedChroma;
if (ftmp1 < 0.0)
ftmp1 = -ftmp1;
ftmp2 = tmp.spec.TekHVC.C - savedChroma;
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;
memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
return(XcmsSuccess);
}
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