/*	Date: 10/05/96  File is: AlphaFilter.java  Release: 1.0
 *	Last Modified: 12/19/96 by: abb@nuccard.eushc.org
 *	Copyright (c) Andrew B. Barclay 1996. All rights reserved.
 */

import java.awt.image.RGBImageFilter ;

class AlphaFilter extends RGBImageFilter {
    int alphaval ;
    int threshold ;

    public AlphaFilter( int alpha ) {
	this( alpha, 0 ) ;
    }

    public AlphaFilter( int alpha, int threshold ) {
	canFilterIndexColorModel = true ;
	alphaval = alpha ;
	this.threshold = 3*threshold ;
System.out.println( "AlphaFilter: threshold="+threshold ) ;
    }

    public int filterRGB( int x, int y, int rgba ) {
	if( threshold > 0 ) {
	    int r = (rgba >> 16) & 0xff ;
	    int g = (rgba >> 8) & 0xff ;
	    int b = rgba & 0xff ;

//System.out.println( "AlphaFilter: checking "+r+","+g+","+b ) ;
	    if( (r+g+b) < threshold ) {
		// Make anything below threshold transparent.
//System.out.println( "AlphaFilter: thresholding "+r+","+g+","+b ) ;
		return (rgba & 0x00ffffff) ;
	    }
	}

	int alpha = (rgba >> 24) & 0xff ;
	alpha = alpha * alphaval / 255 ;
	return ((rgba & 0x00ffffff) | (alpha << 24)) ;
    }
}