/***************************************************************************
 *   Copyright (C) 2004 by Johan Maes                                      *
 *   on4qz@telenet.be                                                      *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include "effects.h"
static inline int blendComponent( int v, int av, int s, int as )
{
    return as*s + av*v -(av*as*s)/255;  
}
    
static inline QRgb blend( QRgb v, QRgb s )
{
    //shadow image is already reduced and blurred
    int as = qAlpha(s); 
    int av = qAlpha(v);
    if ( as == 0 || av == 255 ) return v;

    int a = as + av -(as*av)/255;
    
    int r = blendComponent( qRed(v),av, qRed(s), as)/a;
    int g = blendComponent( qGreen(v),av, qGreen(s), as)/a;
    int b = blendComponent( qBlue(v),av, qBlue(s), as)/a;
    return qRgba(r,g,b,a);
}


void blendImage(QImage &dst,QPoint start,QImage &src)
{
	// pre-multiply source
	int i,j;
	int w=src.width();
	int dx=dst.width();
	int dy=dst.height();
	int h=src.height();
	int posx=start.x();
	int posy=start.y();
	for(j=0;j<h;j++)
		{
			for(i=0;i<w;i++)
				{
					if(((i+posx)>=dx)||((j+posy)>=dy) ||  ((i+posx)<0)||((j+posy)<0)) continue;
					dst.setPixel(i+posx,j+posy,blend(src.pixel(i,j),dst.pixel(i+posx,j+posy)));
				}
		}
}

#define byteCheck(x) if(x<0) x=0;if(x>255) x=255;

void  horizontalGradient(QImage &im,QColor start,QColor end)
{
	int i,j;
	int a,r,g,b;
	double stepA,stepR,stepG,stepB;
	stepA=((double)(qAlpha(end.rgb())-qAlpha(start.rgb())))/im.height();
	stepR=((double)(qRed(end.rgb())-qRed(start.rgb())))/im.height();
	stepG=((double)(qGreen(end.rgb())-qGreen(start.rgb())))/im.height();
	stepB=((double)(qBlue(end.rgb())-qBlue(start.rgb())))/im.height();
	a=qAlpha(start.rgb());
	r=qRed(start.rgb());
	g=qGreen(start.rgb());
	b=qBlue(start.rgb());
	for(j=0;j<im.height();j++)
		{
			QRgb *pp=(QRgb *)im.scanLine(j);
			for(i=0;i<im.width();i++)
				{
					if((pp[i]&0xff000000)!=0)
						{
							pp[i]=qRgba(r,g,b,a);
						}
				}
			a=qRound(qAlpha(start.rgb())+stepA*(double)j);
			r=qRound(qRed(start.rgb())+stepR*(double)j);
			g=qRound(qGreen(start.rgb())+stepG*(double)j);
			b=qRound(qBlue(start.rgb())+stepB*(double)j);
			byteCheck(a);
			byteCheck(r);
			byteCheck(g);
			byteCheck(b);
		}
}



void  verticalGradient(QImage &im,QColor start,QColor end)
{
	int i,j;
	int a,r,g,b;
	double stepA,stepR,stepG,stepB;
	stepA=((double)(qAlpha(end.rgb())-qAlpha(start.rgb())))/im.width();
	stepR=((double)(qRed(end.rgb())-qRed(start.rgb())))/im.width();
	stepG=((double)(qGreen(end.rgb())-qGreen(start.rgb())))/im.width();
	stepB=((double)(qBlue(end.rgb())-qBlue(start.rgb())))/im.width();
	a=qAlpha(start.rgb());
	r=qRed(start.rgb());
	g=qGreen(start.rgb());
	b=qBlue(start.rgb());
	for(i=0;i<im.width();i++)
		{
			
			for(j=0;j<im.height();j++)
				{
					QRgb *pp=(QRgb *)im.scanLine(j);
					if((pp[i]&0xff000000)!=0)
						{
							pp[i]=qRgba(r,g,b,a);
						}
				}
			a=qRound(qAlpha(start.rgb())+stepA*(double)i);
			r=qRound(qRed(start.rgb())+stepR*(double)i);
			g=qRound(qGreen(start.rgb())+stepG*(double)i);
			b=qRound(qBlue(start.rgb())+stepB*(double)i);
			byteCheck(a);
			byteCheck(r);
			byteCheck(g);
			byteCheck(b);
		}
}