hsv.c

Visual_C++[1].NET_Bible1 Visual_C++宝典书中的全部源码

#define mid( a, b, c ) \
	( a >= b && a <= c ? \
	 a : ( b >= a && b <= c ? b : c ) )

void RGB2HSV( int nRed, int nGreen, int nBlue,
	int *nH, int *nS, int *nV )
{
	int nLow, nMid, nHigh;

	if( nRed == nGreen &&
		nGreen == nBlue ){
		*nH = 0;
		*nS = 0;
		*nV = nRed;
		return;
		}

	nLow = min( nRed, min( nGreen, nBlue ) );
	nHigh = max( nRed, max( nGreen, nBlue ) );
	nMid = mid( nRed, nGreen, nBlue );

	*nV = ( nLow + nHigh ) / 2;
	*nS = nHigh - nLow;

	int nCommon = (int)
		( 60.0 * (double) ( nMid - nLow ) /
		(double) ( nHigh - nLow ) );

	if( nRed == nLow && nBlue == nHigh )
		*nH = 240 - nCommon;
	else if( nRed == nLow && nGreen == nHigh )
		*nH = 120 + nCommon;
	else if( nGreen == nLow && nRed == nHigh )
		*nH = 360 - nCommon;
	else if( nGreen == nLow && nBlue == nHigh )
		*nH = 240 - nCommon;
	else if( nBlue == nLow && nGreen == nHigh )
		*nH = 120 - nCommon;
	else if( nBlue == nLow && nRed == nHigh )
		*nH = nCommon;

}