tekhvc.c

早期freebsd实现

    } 
    return(XcmsSuccess);
}

/*
 *	NAME
 *		XcmsTekHVCToCIEuvY - convert TekHVC to CIEuvY
 *
 *	SYNOPSIS
 */
Status
XcmsTekHVCToCIEuvY(ccc, pHVC_WhitePt, pColors_in_out, nColors)
    XcmsCCC ccc;
    XcmsColor *pHVC_WhitePt;
    XcmsColor *pColors_in_out;
    unsigned int nColors;
/*
 *	DESCRIPTION
 *		Transforms an array of TekHVC color specifications, given
 *		their associated white point, to CIECIEuvY.color
 *		specifications.
 *
 *	RETURNS
 *		XcmsFailure if failed, XcmsSuccess otherwise.
 *
 */
{
    XcmsFloat	thetaOffset;
    XcmsColor	*pColor = pColors_in_out;
    XcmsColor	whitePt;
    XcmsCIEuvY	uvY_return;
    XcmsFloat	tempHue, u, v;
    XcmsFloat	tmpVal;
    register int i;

    /*
     * Check arguments
     */
    if (pHVC_WhitePt == NULL || pColors_in_out == NULL) {
	return(XcmsFailure);
    }

    /*
     * Make sure white point is in CIEuvY form
     */
    if (pHVC_WhitePt->format != XcmsCIEuvYFormat) {
	/* Make copy of the white point because we're going to modify it */
	bcopy((char *)pHVC_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
	if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
		XcmsCIEuvYFormat)) {
	    return(XcmsFailure);
	}
	pHVC_WhitePt = &whitePt;
    }
    /* Make sure it is a white point, i.e., Y == 1.0 */
    if (pHVC_WhitePt->spec.CIEuvY.Y != 1.0) {
	return(XcmsFailure);
    }

    /* Get the thetaOffset */
    if (!ThetaOffset(pHVC_WhitePt, &thetaOffset)) {
	return(XcmsFailure);
    }

    /*
     * Now convert each XcmsColor structure to CIEXYZ form
     */
    for (i = 0; i < nColors; i++, pColor++) {

	/* Make sure original format is TekHVC and is valid */
	if (!XcmsTekHVC_ValidSpec(pColor)) {
	    return(XcmsFailure);
	}

	if (pColor->spec.TekHVC.V == 0.0 || pColor->spec.TekHVC.V == 100.0) {
	    if (pColor->spec.TekHVC.V == 100.0) {
		uvY_return.Y = 1.0;
	    } else { /* pColor->spec.TekHVC.V == 0.0 */
		uvY_return.Y = 0.0;
	    }
	    uvY_return.u_prime = pHVC_WhitePt->spec.CIEuvY.u_prime;
	    uvY_return.v_prime = pHVC_WhitePt->spec.CIEuvY.v_prime;
	} else {

	    /* Find the hue based on the white point offset */
	    tempHue = pColor->spec.TekHVC.H + thetaOffset;

	    while (tempHue < 0.0) {
		tempHue += 360.0;
	    }
	    while (tempHue >= 360.0) {
		tempHue -= 360.0;
	    }

	    tempHue = radians(tempHue);

	    /* Calculate u'v' for the obtained hue */
	    u = (XcmsFloat) ((XCMS_COS(tempHue) * pColor->spec.TekHVC.C) / 
		    (pColor->spec.TekHVC.V * (double)CHROMA_SCALE_FACTOR));
	    v = (XcmsFloat) ((XCMS_SIN(tempHue) * pColor->spec.TekHVC.C) / 
		    (pColor->spec.TekHVC.V * (double)CHROMA_SCALE_FACTOR));

	    /* Based on the white point get the offset from best red */
	    uvY_return.u_prime = u + pHVC_WhitePt->spec.CIEuvY.u_prime;
	    uvY_return.v_prime = v + pHVC_WhitePt->spec.CIEuvY.v_prime;

	    /* Calculate the Y value based on the L* = V. */
	    if (pColor->spec.TekHVC.V < 7.99953624) {
		uvY_return.Y = pColor->spec.TekHVC.V / 903.29;
	    } else {
		tmpVal = (pColor->spec.TekHVC.V + 16.0) / 116.0;
		uvY_return.Y = tmpVal * tmpVal * tmpVal; /* tmpVal ** 3 */
	    }
	}

	/* Copy result to pColor */
	bcopy ((char *)&uvY_return, (char *)&pColor->spec, sizeof(XcmsCIEuvY));

	/* Identify that the format is now CIEuvY */
	pColor->format = XcmsCIEuvYFormat;
    }
    return(XcmsSuccess);
}


/*
 *	NAME
 *		XcmsCIEuvYToTekHVC - convert CIEuvY to TekHVC
 *
 *	SYNOPSIS
 */
Status
XcmsCIEuvYToTekHVC(ccc, pHVC_WhitePt, pColors_in_out, nColors)
    XcmsCCC ccc;
    XcmsColor *pHVC_WhitePt;
    XcmsColor *pColors_in_out;
    unsigned int nColors;
/*
 *	DESCRIPTION
 *		Transforms an array of CIECIEuvY.color specifications, given
 *		their assiciated white point, to TekHVC specifications.
 *
 *	RETURNS
 *		XcmsFailure if failed, XcmsSuccess otherwise.
 *
 */
{
    XcmsFloat	theta, L2, u, v, nThetaLow, nThetaHigh;
    XcmsFloat	thetaOffset;
    XcmsColor	*pColor = pColors_in_out;
    XcmsColor	whitePt;
    XcmsTekHVC	HVC_return;
    register int i;

    /*
     * Check arguments
     */
    if (pHVC_WhitePt == NULL || pColors_in_out == NULL) {
	return(XcmsFailure);
    }

    /*
     * Make sure white point is in CIEuvY form
     */
    if (pHVC_WhitePt->format != XcmsCIEuvYFormat) {
	/* Make copy of the white point because we're going to modify it */
	bcopy((char *)pHVC_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
	if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
		XcmsCIEuvYFormat)) {
	    return(XcmsFailure);
	}
	pHVC_WhitePt = &whitePt;
    }
    /* Make sure it is a white point, i.e., Y == 1.0 */
    if (pHVC_WhitePt->spec.CIEuvY.Y != 1.0) {
	return(XcmsFailure);
    }
    if (!ThetaOffset(pHVC_WhitePt, &thetaOffset)) {
	return(XcmsFailure);
    }

    /*
     * Now convert each XcmsColor structure to CIEXYZ form
     */
    for (i = 0; i < nColors; i++, pColor++) {
	if (!XcmsCIEuvY_ValidSpec(pColor)) {
	    return(XcmsFailure);
	}

	/* Use the white point offset to determine HVC */
	u = pColor->spec.CIEuvY.u_prime - pHVC_WhitePt->spec.CIEuvY.u_prime;
	v = pColor->spec.CIEuvY.v_prime - pHVC_WhitePt->spec.CIEuvY.v_prime;

	/* Calculate the offset */
	if (u == 0.0) {
	    theta = 0.0;
	} else {
	    theta = v / u;
	    theta = (XcmsFloat) XCMS_ATAN((double)theta);
	    theta = degrees(theta);
	}

	nThetaLow = 0.0;
	nThetaHigh = 360.0;
	if (u > 0.0 && v > 0.0) {
	    nThetaLow = 0.0;
	    nThetaHigh = 90.0;
	} else if (u < 0.0 && v > 0.0) {
	    nThetaLow = 90.0;
	    nThetaHigh = 180.0;
	} else if (u < 0.0 && v < 0.0) {
	    nThetaLow = 180.0;
	    nThetaHigh = 270.0;
	} else if (u > 0.0 && v < 0.0) {
	    nThetaLow = 270.0;
	    nThetaHigh = 360.0;
	}
	while (theta < nThetaLow) {
		theta += 90.0;
	}
	while (theta >= nThetaHigh) {
	    theta -= 90.0;
	}

	/* calculate the L value from the given Y */
	L2 = (pColor->spec.CIEuvY.Y < 0.008856)
	    ?
	    (pColor->spec.CIEuvY.Y * 903.29)
	    :
	    ((XcmsFloat)(XCMS_CUBEROOT(pColor->spec.CIEuvY.Y) * 116.0) - 16.0);
	HVC_return.C = L2 * CHROMA_SCALE_FACTOR * XCMS_SQRT((double) ((u * u) + (v * v)));
	if (HVC_return.C < 0.0) {
	    theta = 0.0;
	}
	HVC_return.V = L2;
	HVC_return.H = theta - thetaOffset;

	/*
	 * If this is within the error margin let some other routine later
	 * in the chain worry about the slop in the calculations.
	 */
	while (HVC_return.H < -EPS) {
	    HVC_return.H += 360.0;
	}
	while (HVC_return.H >= 360.0 + EPS) {
	    HVC_return.H -= 360.0;
	}

	/* Copy result to pColor */
	bcopy ((char *)&HVC_return, (char *)&pColor->spec, sizeof(XcmsTekHVC));

	/* Identify that the format is now CIEuvY */
	pColor->format = XcmsTekHVCFormat;
    }
    return(XcmsSuccess);
}


/*
 *	NAME
 *		_XcmsTekHVC_CheckModify
 *
 *	SYNOPSIS
 */
int
_XcmsTekHVC_CheckModify(pColor)
    XcmsColor *pColor;
/*
 *	DESCRIPTION
 *		Checks if values in the color specification are valid.
 *		If they are not it modifies the values.
 *		Also brings hue into the range 0.0 <= Hue < 360.0
 *
 *	RETURNS
 *		0 if not valid.
 *		1 if valid.
 *
 */
{
    /* For now only use the TekHVC numbers as inputs */
    if (pColor->format != XcmsTekHVCFormat) {
	return(0);
    }

    if (pColor->spec.TekHVC.V < 0.0) {
	pColor->spec.TekHVC.V = 0.0 + XMY_DBL_EPSILON;
    } else if (pColor->spec.TekHVC.V > 100.0) {
	pColor->spec.TekHVC.V = 100.0 - XMY_DBL_EPSILON;
    }

    if (pColor->spec.TekHVC.C < 0.0) {
	pColor->spec.TekHVC.C = 0.0 - XMY_DBL_EPSILON;
    }

    while (pColor->spec.TekHVC.H < 0.0) {
	pColor->spec.TekHVC.H += 360.0;
    }
    while (pColor->spec.TekHVC.H >= 360.0) {
	pColor->spec.TekHVC.H -= 360.0;
    } 
    return(1);
}