HVCMnV.c revision 1ab64890 
1/* $Xorg: HVCMnV.c,v 1.3 2000/08/17 19:44:37 cpqbld Exp $ */
2
3/*
4 * Code and supporting documentation (c) Copyright 1990 1991 Tektronix, Inc.
5 * 	All Rights Reserved
6 *
7 * This file is a component of an X Window System-specific implementation
8 * of Xcms based on the TekColor Color Management System.  TekColor is a
9 * trademark of Tektronix, Inc.  The term "TekHVC" designates a particular
10 * color space that is the subject of U.S. Patent No. 4,985,853 (equivalent
11 * foreign patents pending).  Permission is hereby granted to use, copy,
12 * modify, sell, and otherwise distribute this software and its
13 * documentation for any purpose and without fee, provided that:
14 *
15 * 1. This copyright, permission, and disclaimer notice is reproduced in
16 *    all copies of this software and any modification thereof and in
17 *    supporting documentation;
18 * 2. Any color-handling application which displays TekHVC color
19 *    cooordinates identifies these as TekHVC color coordinates in any
20 *    interface that displays these coordinates and in any associated
21 *    documentation;
22 * 3. The term "TekHVC" is always used, and is only used, in association
23 *    with the mathematical derivations of the TekHVC Color Space,
24 *    including those provided in this file and any equivalent pathways and
25 *    mathematical derivations, regardless of digital (e.g., floating point
26 *    or integer) representation.
27 *
28 * Tektronix makes no representation about the suitability of this software
29 * for any purpose.  It is provided "as is" and with all faults.
30 *
31 * TEKTRONIX DISCLAIMS ALL WARRANTIES APPLICABLE TO THIS SOFTWARE,
32 * INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
33 * PARTICULAR PURPOSE.  IN NO EVENT SHALL TEKTRONIX BE LIABLE FOR ANY
34 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
35 * RESULTING FROM LOSS OF USE, DATA, OR PROFITS, WHETHER IN AN ACTION OF
36 * CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
37 * CONNECTION WITH THE USE OR THE PERFORMANCE OF THIS SOFTWARE.
38 *
39 *	NAME
40 *		TekHVCMnV.c
41 *
42 *	DESCRIPTION
43 *		Source for XcmsTekHVCQueryMinV gamut boundary querying routine.
44 *
45 */
46/* $XFree86$ */
47
48#ifdef HAVE_CONFIG_H
49#include <config.h>
50#endif
51#include "Xlibint.h"
52#include "Xcmsint.h"
53#include "Cv.h"
54
55/*
56 *	DEFINES
57 */
58#define EPS	    0.001
59
60
61/************************************************************************
62 *									*
63 *			 PUBLIC ROUTINES				*
64 *									*
65 ************************************************************************/
66
67/*
68 *	NAME
69 *		XcmsTekHVCQueryMinV - Compute minimum value for hue and chroma
70 *
71 *	SYNOPSIS
72 */
73Status
74XcmsTekHVCQueryMinV (
75    XcmsCCC ccc,
76    XcmsFloat hue,
77    XcmsFloat chroma,
78    XcmsColor *pColor_return)
79
80/*
81 *	DESCRIPTION
82 *		Return the minimum value for a specific hue, and the
83 *		corresponding chroma.  The input color specification
84 *		may be in any format, however output is in XcmsTekHVCFormat.
85 *
86 *		Since this routine works with the value within
87 *		pColor_return intermediate results may be returned
88 *		even though it may be invalid.
89 *
90 *	ASSUMPTIONS
91 *		This routine assumes that the white point associated with
92 *		the color specification is the Screen White Point.  The
93 *		Screen White Point will also be associated with the
94 *		returned color specification.
95 *
96 *	RETURNS
97 *		XcmsFailure - Failure
98 *		XcmsSuccess - Succeeded with no modifications
99 *
100 */
101{
102    XcmsCCCRec myCCC;
103    XcmsColor tmp;
104    XcmsColor max_vc;
105
106    /*
107     * Check Arguments
108     */
109    if (ccc == NULL || pColor_return == NULL) {
110	return(XcmsFailure);
111    }
112
113    /*
114     * Insure TekHVC installed
115     */
116    if (XcmsAddColorSpace(&XcmsTekHVCColorSpace) == XcmsFailure) {
117	return(XcmsFailure);
118    }
119
120    /* Use my own CCC */
121    memcpy ((char *)&myCCC, (char *)ccc, sizeof(XcmsCCCRec));
122    myCCC.clientWhitePt.format = XcmsUndefinedFormat;/* inherit screen white pt */
123    myCCC.gamutCompProc = (XcmsCompressionProc)NULL;/* no gamut comp func */
124
125    tmp.spec.TekHVC.H = hue;
126    tmp.spec.TekHVC.V = 100.0;
127    tmp.spec.TekHVC.C = chroma;
128    tmp.pixel = pColor_return->pixel;
129    tmp.format = XcmsTekHVCFormat;
130
131
132    /* Check for a valid HVC */
133    if (!_XcmsTekHVC_CheckModify (&tmp)) {
134	return(XcmsFailure);
135    }
136
137    /* Step 1: compute the maximum value and chroma for this hue. */
138    /*         This copy may be overkill but it preserves the pixel etc. */
139    memcpy((char *)&max_vc, (char *)&tmp, sizeof(XcmsColor));
140    if (_XcmsTekHVCQueryMaxVCRGB (&myCCC, max_vc.spec.TekHVC.H, &max_vc,
141	    (XcmsRGBi *)NULL) == XcmsFailure) {
142	return(XcmsFailure);
143    }
144
145    /* Step 2: find the intersection with the maximum hvc and chroma line. */
146    if (tmp.spec.TekHVC.C > max_vc.spec.TekHVC.C + EPS) {
147	/* If the chroma is to large then return maximum hvc. */
148	tmp.spec.TekHVC.C = max_vc.spec.TekHVC.C;
149	tmp.spec.TekHVC.V = max_vc.spec.TekHVC.V;
150    } else {
151	tmp.spec.TekHVC.V = tmp.spec.TekHVC.C *
152		max_vc.spec.TekHVC.V / max_vc.spec.TekHVC.C;
153	if (tmp.spec.TekHVC.V > max_vc.spec.TekHVC.V) {
154	    tmp.spec.TekHVC.V = max_vc.spec.TekHVC.V;
155	} else if (tmp.spec.TekHVC.V < 0.0) {
156	    tmp.spec.TekHVC.V = tmp.spec.TekHVC.C = 0.0;
157	}
158    }
159    if (_XcmsTekHVC_CheckModify (&tmp)) {
160	memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
161	return(XcmsSuccess);
162    } else {
163	return(XcmsFailure);
164    }
165}
166