/*
*	SDL Graphics Extension
*	Pixel, surface and color functions
*
*	Started 990815 (split from sge_draw 010611)
*
*	License: LGPL v2+ (see the file LICENSE)
*	(c)1999-2001 Anders Lindström
*/

/*********************************************************************
 *  This library is free software; you can redistribute it and/or    *
 *  modify it under the terms of the GNU Library General Public      *
 *  License as published by the Free Software Foundation; either     *
 *  version 2 of the License, or (at your option) any later version. *
 *********************************************************************/

/*
*  Some of this code is taken from the "Introduction to SDL" and
*  John Garrison's PowerPak	
*/

#include "SDL.h"
#include <math.h>
#include <string.h>
#include <stdarg.h>
#include "sge_surface.h"


/* Globals used for sge_Update/sge_Lock */
Uint8 _sge_update=1;
Uint8 _sge_lock=1;


/**********************************************************************************/
/**                            Misc. functions                                   **/
/**********************************************************************************/

//==================================================================================
// Turns off automatic update (to avoid tearing).
//==================================================================================
void sge_Update_OFF(void)
{
	_sge_update=0;	
}

//==================================================================================
// Turns on automatic update (default)
//==================================================================================
void sge_Update_ON(void)
{
	_sge_update=1;	
}

//==================================================================================
// Turns off automatic locking of surfaces
//==================================================================================
void sge_Lock_OFF(void)
{
	_sge_lock=0;	
}

//==================================================================================
// Turns on automatic locking (default)
//==================================================================================
void sge_Lock_ON(void)
{
	_sge_lock=1;	
}

//==================================================================================
// Returns update&locking mode (1-on and 0-off)
//==================================================================================
Uint8 sge_getUpdate(void)
{
  return _sge_update;
}
Uint8 sge_getLock(void)
{
  return _sge_lock;
}


//==================================================================================
// SDL_UpdateRect does nothing if any part of the rectangle is outside the surface
// --- This version always work
//==================================================================================
void sge_UpdateRect(SDL_Surface *screen, Sint16 x, Sint16 y, Uint16 w, Uint16 h)
{
	if(_sge_update!=1 || screen != SDL_GetVideoSurface()){return;}
	
	if(x>=screen->w || y>=screen->h){return;}
	
	Sint16 a,b;

	a=w; b=h;

	
	if(x < 0){x=0;}
	if(y < 0){y=0;}
	
	if(a+x > screen->w){a=screen->w-x;}
	if(b+y > screen->h){b=screen->h-y;}

	SDL_UpdateRect(screen,x,y,a,b);
}


//==================================================================================
// Creates a 32bit (8/8/8/8) alpha surface
// Map colors with sge_MapAlpha() and then use the Uint32 color versions of
// SGEs routines
//==================================================================================
SDL_Surface *sge_CreateAlphaSurface(Uint32 flags, int width, int height)
{
	return SDL_CreateRGBSurface(flags,width,height,32, 0xFF000000, 0x00FF0000, 0x0000FF00, 0x000000FF);
}


//==================================================================================
// Returns the Uint32 color value for a 32bit (8/8/8/8) alpha surface
//==================================================================================
Uint32 sge_MapAlpha(Uint8 R, Uint8 G, Uint8 B, Uint8 A)
{
	Uint32 color=0;
	
	color|=R<<24;
	color|=G<<16;
	color|=B<<8;
	color|=A;
	
	return color;
}


//==================================================================================
// Sets an SDL error string
// Accepts formated argument - like printf()
// SDL_SetError() also does this, but it does not use standard syntax (why?)
//==================================================================================
void sge_SetError(const char *format, ...)
{
	char buf[256];

	va_list ap;
	
	#ifdef __WIN32__
	va_start((va_list*)ap, format); //Stupid w32 crosscompiler
	#else
	va_start(ap, format);
	#endif
	
	vsprintf(buf, format, ap);
	va_end(ap);

	SDL_SetError(buf);
}



/**********************************************************************************/
/**                            Pixel functions                                   **/
/**********************************************************************************/

//==================================================================================
// Fast put pixel
//==================================================================================
void _PutPixel(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color)
{
	if(x>=sge_clip_xmin(surface) && x<=sge_clip_xmax(surface) && y>=sge_clip_ymin(surface) && y<=sge_clip_ymax(surface)){
		switch (surface->format->BytesPerPixel) {
			case 1: { /* Assuming 8-bpp */
				*((Uint8 *)surface->pixels + y*surface->pitch + x) = color;
			}
			break;

			case 2: { /* Probably 15-bpp or 16-bpp */
				*((Uint16 *)surface->pixels + y*surface->pitch/2 + x) = color;
			}
			break;

			case 3: { /* Slow 24-bpp mode, usually not used */
				Uint8 *pix = (Uint8 *)surface->pixels + y * surface->pitch + x*3;

  				/* Gack - slow, but endian correct */
				*(pix+surface->format->Rshift/8) = color>>surface->format->Rshift;
  				*(pix+surface->format->Gshift/8) = color>>surface->format->Gshift;
  				*(pix+surface->format->Bshift/8) = color>>surface->format->Bshift;
				*(pix+surface->format->Ashift/8) = color>>surface->format->Ashift;
			}
			break;

			case 4: { /* Probably 32-bpp */
				*((Uint32 *)surface->pixels + y*surface->pitch/4 + x) = color;
			}
			break;
		}
	}

}


//==================================================================================
// Fast put pixel (RGB)
//==================================================================================
void _PutPixel(SDL_Surface *surface, Sint16 x, Sint16 y, Uint8 R, Uint8 G, Uint8 B)
{
	_PutPixel(surface,x,y, SDL_MapRGB(surface->format, R, G, B));
}


//==================================================================================
// Fastest put pixel functions (don't mess up indata, thank you)
//==================================================================================
void _PutPixel8(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color)
{
	*((Uint8 *)surface->pixels + y*surface->pitch + x) = color;
}
void _PutPixel16(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color)
{
	*((Uint16 *)surface->pixels + y*surface->pitch/2 + x) = color;
}
void _PutPixel24(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color)
{
	Uint8 *pix = (Uint8 *)surface->pixels + y * surface->pitch + x*3;

  	/* Gack - slow, but endian correct */
	*(pix+surface->format->Rshift/8) = color>>surface->format->Rshift;
  	*(pix+surface->format->Gshift/8) = color>>surface->format->Gshift;
  	*(pix+surface->format->Bshift/8) = color>>surface->format->Bshift;
	*(pix+surface->format->Ashift/8) = color>>surface->format->Ashift;
}
void _PutPixel32(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color)
{
	*((Uint32 *)surface->pixels + y*surface->pitch/4 + x) = color;
}
void _PutPixelX(SDL_Surface *dest,Sint16 x,Sint16 y,Uint32 color)
{
	switch ( dest->format->BytesPerPixel ) {
	case 1:
		*((Uint8 *)dest->pixels + y*dest->pitch + x) = color;
		break;
	case 2:
		*((Uint16 *)dest->pixels + y*dest->pitch/2 + x) = color;
		break;
	case 3:
		_PutPixel24(dest,x,y,color);
		break;
	case 4:
		*((Uint32 *)dest->pixels + y*dest->pitch/4 + x) = color;
		break;
	}
}


//==================================================================================
// Safe put pixel
//==================================================================================
void sge_PutPixel(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color)
{

	if ( SDL_MUSTLOCK(surface) && _sge_lock ) {
		if ( SDL_LockSurface(surface) < 0 ) {
			return;
		}
	}

	_PutPixel(surface, x, y, color);

	if ( SDL_MUSTLOCK(surface) && _sge_lock ) {
		SDL_UnlockSurface(surface);
	}

	if(_sge_update!=1){return;}
	sge_UpdateRect(surface, x, y, 1, 1);
}


//==================================================================================
// Safe put pixel (RGB)
//==================================================================================
void sge_PutPixel(SDL_Surface *surface, Sint16 x, Sint16 y, Uint8 R, Uint8 G, Uint8 B)
{
  sge_PutPixel(surface,x,y, SDL_MapRGB(surface->format, R, G, B));
}


//==================================================================================
// Calculate y pitch offset
// (the y pitch offset is constant for the same y coord and surface)
//==================================================================================
Sint32 sge_CalcYPitch(SDL_Surface *dest,Sint16 y)
{
	if(y>=sge_clip_ymin(dest) && y<=sge_clip_ymax(dest)){
		switch ( dest->format->BytesPerPixel ) {
		case 1:
			return y*dest->pitch;
			break;
		case 2:
			return y*dest->pitch/2;
			break;
		case 3:
			return y*dest->pitch;
			break;
		case 4:
			return y*dest->pitch/4;
			break;
		}
	}
	
	return -1;
}


//==================================================================================
// Put pixel with precalculated y pitch offset
//==================================================================================
void sge_pPutPixel(SDL_Surface *surface, Sint16 x, Sint32 ypitch, Uint32 color)
{
	if(x>=sge_clip_xmin(surface) && x<=sge_clip_xmax(surface) && ypitch>=0){
		switch (surface->format->BytesPerPixel) {
			case 1: { /* Assuming 8-bpp */
				*((Uint8 *)surface->pixels + ypitch + x) = color;
			}
			break;

			case 2: { /* Probably 15-bpp or 16-bpp */
				*((Uint16 *)surface->pixels + ypitch + x) = color;
			}
			break;

			case 3: { /* Slow 24-bpp mode, usually not used */
  				/* Gack - slow, but endian correct */
  				Uint8 *pix = (Uint8 *)surface->pixels + ypitch + x*3;

				*(pix+surface->format->Rshift/8) = color>>surface->format->Rshift;
  				*(pix+surface->format->Gshift/8) = color>>surface->format->Gshift;
  				*(pix+surface->format->Bshift/8) = color>>surface->format->Bshift;
				*(pix+surface->format->Ashift/8) = color>>surface->format->Ashift;
			}
			break;

			case 4: { /* Probably 32-bpp */
				*((Uint32 *)surface->pixels + ypitch + x) = color;
			}
			break;
		}
	}
}


//==================================================================================
// Get pixel
//==================================================================================
Uint32 sge_GetPixel(SDL_Surface *surface, Sint16 x, Sint16 y)
{
	switch (surface->format->BytesPerPixel) {
		case 1: { /* Assuming 8-bpp */
			return *((Uint8 *)surface->pixels + y*surface->pitch + x);
		}
		break;

		case 2: { /* Probably 15-bpp or 16-bpp */
			return *((Uint16 *)surface->pixels + y*surface->pitch/2 + x);
		}
		break;

		case 3: { /* Slow 24-bpp mode, usually not used */
			Uint8 *pix;
			int shift;
			Uint32 color=0;

			pix = (Uint8 *)surface->pixels + y * surface->pitch + x*3;
			shift = surface->format->Rshift;
			color = *(pix+shift/8)<<shift;
			shift = surface->format->Gshift;
			color|= *(pix+shift/8)<<shift;
			shift = surface->format->Bshift;
			color|= *(pix+shift/8)<<shift;
			shift = surface->format->Ashift;
			color|= *(pix+shift/8)<<shift;
			return color;
		}
		break;

		case 4: { /* Probably 32-bpp */
			return *((Uint32 *)surface->pixels + y*surface->pitch/4 + x);
		}
		break;
	}
	return 0;
}


//==================================================================================
// Put pixel with alpha blending
//==================================================================================
void _PutPixelAlpha(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color, Uint8 alpha)
{
	if(x>=sge_clip_xmin(surface) && x<=sge_clip_xmax(surface) && y>=sge_clip_ymin(surface) && y<=sge_clip_ymax(surface)){
		Uint32 Rmask = surface->format->Rmask, Gmask = surface->format->Gmask, Bmask = surface->format->Bmask, Amask = surface->format->Amask;
		Uint32 R,G,B,A=0;
	
		switch (surface->format->BytesPerPixel) {
			case 1: { /* Assuming 8-bpp */
				if( alpha == 255 ){
					*((Uint8 *)surface->pixels + y*surface->pitch + x) = color;
				}else{
					Uint8 *pixel = (Uint8 *)surface->pixels + y*surface->pitch + x;
					
					Uint8 dR = surface->format->palette->colors[*pixel].r;
					Uint8 dG = surface->format->palette->colors[*pixel].g;
					Uint8 dB = surface->format->palette->colors[*pixel].b;
					Uint8 sR = surface->format->palette->colors[color].r;
					Uint8 sG = surface->format->palette->colors[color].g;
					Uint8 sB = surface->format->palette->colors[color].b;
					
					dR = dR + ((sR-dR)*alpha >> 8);
					dG = dG + ((sG-dG)*alpha >> 8);
					dB = dB + ((sB-dB)*alpha >> 8);
				
					*pixel = SDL_MapRGB(surface->format, dR, dG, dB);
				}
			}
			break;

			case 2: { /* Probably 15-bpp or 16-bpp */		
				if( alpha == 255 ){
					*((Uint16 *)surface->pixels + y*surface->pitch/2 + x) = color;
				}else{
					Uint16 *pixel = (Uint16 *)surface->pixels + y*surface->pitch/2 + x;
					Uint32 dc = *pixel;
				
					R = ((dc & Rmask) + (( (color & Rmask) - (dc & Rmask) ) * alpha >> 8)) & Rmask;
					G = ((dc & Gmask) + (( (color & Gmask) - (dc & Gmask) ) * alpha >> 8)) & Gmask;
					B = ((dc & Bmask) + (( (color & Bmask) - (dc & Bmask) ) * alpha >> 8)) & Bmask;
					if( Amask )
						A = ((dc & Amask) + (( (color & Amask) - (dc & Amask) ) * alpha >> 8)) & Amask;

					*pixel= R | G | B | A;
				}
			}
			break;

			case 3: { /* Slow 24-bpp mode, usually not used */
				Uint8 *pix = (Uint8 *)surface->pixels + y * surface->pitch + x*3;
				Uint8 rshift8=surface->format->Rshift/8;
				Uint8 gshift8=surface->format->Gshift/8;
				Uint8 bshift8=surface->format->Bshift/8;
				Uint8 ashift8=surface->format->Ashift/8;
				
				
				if( alpha == 255 ){
  					*(pix+rshift8) = color>>surface->format->Rshift;
  					*(pix+gshift8) = color>>surface->format->Gshift;
  					*(pix+bshift8) = color>>surface->format->Bshift;
					*(pix+ashift8) = color>>surface->format->Ashift;
				}else{
					Uint8 dR, dG, dB, dA=0;
					Uint8 sR, sG, sB, sA=0;
					
					pix = (Uint8 *)surface->pixels + y * surface->pitch + x*3;
					
					dR = *((pix)+rshift8); 
            		dG = *((pix)+gshift8);
            		dB = *((pix)+bshift8);
					dA = *((pix)+ashift8);
					
					sR = (color>>surface->format->Rshift)&0xff;
					sG = (color>>surface->format->Gshift)&0xff;
					sB = (color>>surface->format->Bshift)&0xff;
					sA = (color>>surface->format->Ashift)&0xff;
					
					dR = dR + ((sR-dR)*alpha >> 8);
					dG = dG + ((sG-dG)*alpha >> 8);
					dB = dB + ((sB-dB)*alpha >> 8);
					dA = dA + ((sA-dA)*alpha >> 8);

					*((pix)+rshift8) = dR; 
            		*((pix)+gshift8) = dG;
            		*((pix)+bshift8) = dB;
					*((pix)+ashift8) = dA;
				}
			}
			break;

			case 4: { /* Probably 32-bpp */
				if( alpha == 255 ){
					*((Uint32 *)surface->pixels + y*surface->pitch/4 + x) = color;
				}else{
					Uint32 *pixel = (Uint32 *)surface->pixels + y*surface->pitch/4 + x;
					Uint32 dc = *pixel;
			
					R = ((dc & Rmask) + (( (color & Rmask) - (dc & Rmask) ) * alpha >> 8)) & Rmask;
					G = ((dc & Gmask) + (( (color & Gmask) - (dc & Gmask) ) * alpha >> 8)) & Gmask;
					B = ((dc & Bmask) + (( (color & Bmask) - (dc & Bmask) ) * alpha >> 8)) & Bmask;
					if( Amask )
						A = ((dc & Amask) + (( (color & Amask) - (dc & Amask) ) * alpha >> 8)) & Amask;
					
					*pixel = R | G | B | A;
				}
			}
			break;
		}
	}
}

void sge_PutPixelAlpha(SDL_Surface *surface, Sint16 x, Sint16 y, Uint32 color, Uint8 alpha)
{
	if ( SDL_MUSTLOCK(surface) && _sge_lock )
		if ( SDL_LockSurface(surface) < 0 )
			return;

	_PutPixelAlpha(surface,x,y,color,alpha);
	
	/* unlock the display */
	if (SDL_MUSTLOCK(surface) && _sge_lock) {
		SDL_UnlockSurface(surface);
	}
	
	if(_sge_update!=1){return;}
	sge_UpdateRect(surface, x, y, 1, 1);
}


void _PutPixelAlpha(SDL_Surface *surface, Sint16 x, Sint16 y, Uint8 R, Uint8 G, Uint8 B, Uint8 alpha)
{
  _PutPixelAlpha(surface,x,y, SDL_MapRGB(surface->format, R, G, B),alpha);
}
void sge_PutPixelAlpha(SDL_Surface *surface, Sint16 x, Sint16 y, Uint8 R, Uint8 G, Uint8 B, Uint8 alpha)
{
  sge_PutPixelAlpha(surface,x,y, SDL_MapRGB(surface->format, R, G, B), alpha);
}



/**********************************************************************************/
/**                            Block functions                                   **/
/**********************************************************************************/

//==================================================================================
// The sge_write_block* functions copies the given block (a surface line) directly
// to the surface. This is *much* faster then using the put pixel functions to
// update a line. The block consist of Surface->w (the width of the surface) numbers
// of color values. Note the difference in byte size for the block elements for
// different color dephts. 24 bpp is slow and not included!
//==================================================================================
void sge_write_block8(SDL_Surface *Surface, Uint8 *block, Sint16 y)
{
	memcpy(	(Uint8 *)Surface->pixels + y*Surface->pitch, block, sizeof(Uint8)*Surface->w );
}
void sge_write_block16(SDL_Surface *Surface, Uint16 *block, Sint16 y)
{
	memcpy(	(Uint16 *)Surface->pixels + y*Surface->pitch/2, block, sizeof(Uint16)*Surface->w );
}
void sge_write_block32(SDL_Surface *Surface, Uint32 *block, Sint16 y)
{
	memcpy(	(Uint32 *)Surface->pixels + y*Surface->pitch/4, block, sizeof(Uint32)*Surface->w );
}


//==================================================================================
// ...and get
//==================================================================================
void sge_read_block8(SDL_Surface *Surface, Uint8 *block, Sint16 y)
{
	memcpy(	block,(Uint8 *)Surface->pixels + y*Surface->pitch, sizeof(Uint8)*Surface->w );
}
void sge_read_block16(SDL_Surface *Surface, Uint16 *block, Sint16 y)
{
	memcpy(	block,(Uint16 *)Surface->pixels + y*Surface->pitch/2, sizeof(Uint16)*Surface->w );
}
void sge_read_block32(SDL_Surface *Surface, Uint32 *block, Sint16 y)
{
	memcpy(	block,(Uint32 *)Surface->pixels + y*Surface->pitch/4, sizeof(Uint32)*Surface->w );
}



/**********************************************************************************/
/**                       Blitting/surface functions                             **/
/**********************************************************************************/

//==================================================================================
// Clear surface to color
//==================================================================================
void sge_ClearSurface(SDL_Surface *Surface, Uint32 color)
{

	SDL_FillRect(Surface,NULL, color);

	if(_sge_update!=1){return;}
	SDL_UpdateRect(Surface, 0,0,0,0);
}


//==================================================================================
// Clear surface to color (RGB)
//==================================================================================
void sge_ClearSurface(SDL_Surface *Surface, Uint8 R, Uint8 G, Uint8 B)
{
	sge_ClearSurface(Surface,SDL_MapRGB(Surface->format, R, G, B));
}


//==================================================================================
// Blit from one surface to another
// Warning! Alpha and color key is lost (=0) on Src surface
//==================================================================================
int sge_BlitTransparent(SDL_Surface *Src, SDL_Surface *Dest, Sint16 SrcX, Sint16 SrcY, Sint16 DestX, Sint16 DestY, Sint16 W, Sint16 H, Uint32 Clear, Uint8 Alpha)
{
 	SDL_Rect src, dest;
	int ret;

	/* Dest clipping */
	#if SDL_VERSIONNUM(SDL_MAJOR_VERSION, SDL_MINOR_VERSION, SDL_PATCHLEVEL) < \
    SDL_VERSIONNUM(1, 1, 5)
	int flag=0;	
	if (DestX < Dest->clip_minx){
		SrcX += Dest->clip_minx-DestX;
		W -= Dest->clip_minx-DestX-1;
		DestX=Dest->clip_minx;
 	}
	if (DestY < Dest->clip_miny){
		SrcY +=Dest->clip_miny-DestY;
		H -= Dest->clip_miny-DestY-1;
 		DestY=Dest->clip_miny;
 	}
	if ((DestX + W) > Dest->clip_maxx){
		W = W - ((DestX + W) - Dest->clip_maxx)+1;
		if(W<=0){SDL_SetError("SGE - Blit error");return -1;}
 	}
 	if ((DestY + H) > Dest->clip_maxy){
		H = H - ((DestY + H) - Dest->clip_maxy)+1;
		if(H<=0){SDL_SetError("SGE - Blit error");return -1;}
 	}
	#endif

 	/* Initialize our rectangles */
 	src.x = SrcX;
 	src.y = SrcY;
 	src.w = W;
 	src.h = H;

 	dest.x = DestX;
 	dest.y = DestY;
 	dest.w = W;
 	dest.h = H;

	/* We don't care about src clipping, only dest! */
	#if SDL_VERSIONNUM(SDL_MAJOR_VERSION, SDL_MINOR_VERSION, SDL_PATCHLEVEL) < \
    SDL_VERSIONNUM(1, 1, 5)
	if ( (Src->flags & SDL_SRCCLIPPING) == SDL_SRCCLIPPING){
		Src->flags &= ~SDL_SRCCLIPPING; flag=1;
	}
	#endif

 	/* Set the color to be transparent */
 	SDL_SetColorKey(Src, SDL_SRCCOLORKEY, Clear);

 	/* Set the alpha value */
 	SDL_SetAlpha(Src, SDL_SRCALPHA, Alpha);

	/* Blit */	
 	ret=SDL_BlitSurface(Src, &src, Dest, &dest);

	/* Set the correct flag */
	#if SDL_VERSIONNUM(SDL_MAJOR_VERSION, SDL_MINOR_VERSION, SDL_PATCHLEVEL) < \
    SDL_VERSIONNUM(1, 1, 5)
	if (flag==1){
		Src->flags |= SDL_SRCCLIPPING;
	}
	#endif

	/* Set normal levels */
	SDL_SetAlpha(Src,0,0);
	SDL_SetColorKey(Src,0,0);

	return ret;
}


//==================================================================================
// Blit from one surface to another (not touching alpha or color key -
// use SDL_SetColorKey and SDL_SetAlpha)
//==================================================================================
int sge_Blit(SDL_Surface *Src, SDL_Surface *Dest, Sint16 SrcX, Sint16 SrcY, Sint16 DestX, Sint16 DestY, Sint16 W, Sint16 H)
{
	SDL_Rect src, dest;
	int ret;

	/* Dest clipping */
	#if SDL_VERSIONNUM(SDL_MAJOR_VERSION, SDL_MINOR_VERSION, SDL_PATCHLEVEL) < \
    SDL_VERSIONNUM(1, 1, 5)
	int flag=0;		
	if (DestX < Dest->clip_minx){
		SrcX += Dest->clip_minx-DestX;
		W -= Dest->clip_minx-DestX -1;
		DestX=Dest->clip_minx;
 	}
	if (DestY < Dest->clip_miny){
		SrcY +=Dest->clip_miny-DestY;
		H -= Dest->clip_miny-DestY -1;
 		DestY=Dest->clip_miny;
 	}
	if ((DestX + W) > Dest->clip_maxx){
		W = W - ((DestX + W) - Dest->clip_maxx)+1;
		if(W<=0){SDL_SetError("SGE - Blit error");return -1;}
	}
 	if ((DestY + H) > Dest->clip_maxy){
		H = H - ((DestY + H) - Dest->clip_maxy)+1;
		if(H<=0){SDL_SetError("SGE - Blit error");return -1;}
 	}
	#endif

 	/* Initialize our rectangles */
 	src.x = SrcX;
 	src.y = SrcY;
 	src.w = W;
 	src.h = H;

 	dest.x = DestX;
 	dest.y = DestY;
 	dest.w = W;
 	dest.h = H;

	/* We don't care about src clipping, only dest! */
	#if SDL_VERSIONNUM(SDL_MAJOR_VERSION, SDL_MINOR_VERSION, SDL_PATCHLEVEL) < \
    SDL_VERSIONNUM(1, 1, 5)
	if ( (Src->flags & SDL_SRCCLIPPING) == SDL_SRCCLIPPING){
		Src->flags &= ~SDL_SRCCLIPPING; flag=1;
	}
	#endif

	/* Blit */
 	ret=SDL_BlitSurface(Src, &src, Dest, &dest);

	/* Set the correct flag */
	#if SDL_VERSIONNUM(SDL_MAJOR_VERSION, SDL_MINOR_VERSION, SDL_PATCHLEVEL) < \
    SDL_VERSIONNUM(1, 1, 5)
	if (flag==1){
		Src->flags |= SDL_SRCCLIPPING;
	}
	#endif

	return ret;
}


//==================================================================================
// Copies a surface to a new...
//==================================================================================
SDL_Surface *sge_copy_surface(SDL_Surface *src)
{
	return SDL_ConvertSurface(src, src->format,SDL_SWSURFACE);
}



SDL_Surface *sge_copy_surface(SDL_Surface *a_poSource, Sint16 x, Sint16 y, Sint16 w, Sint16 h)
{
	SDL_Surface* poDest;
	poDest = SDL_CreateRGBSurface( SDL_SWSURFACE, w, h, a_poSource->format->BitsPerPixel,
		a_poSource->format->Rmask, a_poSource->format->Gmask, a_poSource->format->Bmask, a_poSource->format->Amask );
	if ( a_poSource->format->BitsPerPixel <= 8 )
	{
		SDL_SetColors( poDest, a_poSource->format->palette->colors, 0, a_poSource->format->palette->ncolors );
	}

	sge_Blit( a_poSource, poDest, x, y, 0, 0, w, h );
	return poDest;
}





/**********************************************************************************/
/**                            Palette functions                                 **/
/**********************************************************************************/
//==================================================================================
// Fill in a palette entry with R, G, B componenets
//==================================================================================
SDL_Color sge_FillPaletteEntry(Uint8 R, Uint8 G, Uint8 B)
{
   SDL_Color color;

   color.r = R;
   color.g = G;
   color.b = B;

   return color;
}


//==================================================================================
// Get the RGB of a color value
// Needed in those dark days before SDL 1.0
//==================================================================================
SDL_Color sge_GetRGB(SDL_Surface *Surface, Uint32 Color)
{
	SDL_Color rgb;
	SDL_GetRGB(Color, Surface->format, &(rgb.r), &(rgb.g), &(rgb.b));

	return(rgb);
}


//==================================================================================
// Fades from (sR,sG,sB) to (dR,dG,dB), puts result in ctab[start] to ctab[stop]
//==================================================================================
void sge_Fader(SDL_Surface *Surface, Uint8 sR,Uint8 sG,Uint8 sB, Uint8 dR,Uint8 dG,Uint8 dB,Uint32 *ctab,int start, int stop)
{
	// (sR,sG,sB) and (dR,dG,dB) are two points in space (the RGB cube). 	

	/* The vector for the straight line */
	int v[3];
	v[0]=dR-sR; v[1]=dG-sG; v[2]=dB-sB;

	/* Ref. point */
	int x0=sR, y0=sG, z0=sB;

	// The line's equation is:
	// x= x0 + v[0] * t
	// y= y0 + v[1] * t
	// z= z0 + v[2] * t
	//
	// (x,y,z) will travel between the two points when t goes from 0 to 1.

	int i=start;
 	double step=1.0/((stop+1)-start);

	for(double t=0.0; t<=1.0 && i<=stop ; t+=step){
		ctab[i++]=SDL_MapRGB(Surface->format, (Uint8)(x0+v[0]*t), (Uint8)(y0+v[1]*t), (Uint8)(z0+v[2]*t) );
	}			
}


//==================================================================================
// Fades from (sR,sG,sB,sA) to (dR,dG,dB,dA), puts result in ctab[start] to ctab[stop]
//==================================================================================
void sge_AlphaFader(Uint8 sR,Uint8 sG,Uint8 sB,Uint8 sA, Uint8 dR,Uint8 dG,Uint8 dB,Uint8 dA, Uint32 *ctab,int start, int stop)
{
	// (sR,sG,sB,sA) and (dR,dG,dB,dA) are two points in hyperspace (the RGBA hypercube). 	

	/* The vector for the straight line */
	int v[4];
	v[0]=dR-sR; v[1]=dG-sG; v[2]=dB-sB; v[3]=dA-sA;

	/* Ref. point */
	int x0=sR, y0=sG, z0=sB, w0=sA;

	// The line's equation is:
	// x= x0 + v[0] * t
	// y= y0 + v[1] * t
	// z= z0 + v[2] * t
	// w= w0 + v[3] * t
	//
	// (x,y,z,w) will travel between the two points when t goes from 0 to 1.

	int i=start;
 	double step=1.0/((stop+1)-start);

	for(double t=0.0; t<=1.0 && i<=stop ; t+=step)
		ctab[i++]=sge_MapAlpha((Uint8)(x0+v[0]*t), (Uint8)(y0+v[1]*t), (Uint8)(z0+v[2]*t), (Uint8)(w0+v[3]*t));
					
}


//==================================================================================
// Copies a nice rainbow palette to the color table (ctab[start] to ctab[stop]).
// You must also set the intensity of the palette (0-bright 255-dark)
//==================================================================================
void sge_SetupRainbowPalette(SDL_Surface *Surface,Uint32 *ctab,int intensity, int start, int stop)
{
	int slice=(int)((stop-start)/6);

	/* Red-Yellow */
	sge_Fader(Surface, 255,intensity,intensity, 255,255,intensity, ctab, start,slice);
 	/* Yellow-Green */
	sge_Fader(Surface, 255,255,intensity, intensity,255,intensity, ctab, slice+1, 2*slice);
 	/* Green-Turquoise blue */
	sge_Fader(Surface, intensity,255,intensity, intensity,255,255, ctab, 2*slice+1, 3*slice);
 	/* Turquoise blue-Blue */
	sge_Fader(Surface, intensity,255,255, intensity,intensity,255, ctab, 3*slice+1, 4*slice);
 	/* Blue-Purple */
	sge_Fader(Surface, intensity,intensity,255, 255,intensity,255, ctab, 4*slice+1, 5*slice);	
 	/* Purple-Red */
	sge_Fader(Surface, 255,intensity,255, 255,intensity,intensity, ctab, 5*slice+1, stop);	
}


//==================================================================================
// Copies a B&W palette to the color table (ctab[start] to ctab[stop]).
//==================================================================================
void sge_SetupBWPalette(SDL_Surface *Surface,Uint32 *ctab,int start, int stop)
{
	sge_Fader(Surface, 0,0,0, 255,255,255, ctab,start,stop);
}