// blend1.cpp : DLL アプリケーションのエントリ ポイントを定義します。
//

#include "stdafx.h"
#include <math.h>
#include <stdlib.h>



#ifdef _MANAGED
#pragma managed(push, off)
#endif



extern "C" {
typedef unsigned char n_byte;

int __stdcall get_blend_func_count();
char* __stdcall get_blend_func_key(int no);
char* __stdcall get_blend_func_name(int no);
void __stdcall blend(unsigned char* dst,const unsigned char* col,const unsigned char* alpha,int col_step
								 ,int alpha_step,int num_channel,int num_pixel,int no);



//追加する合成方法の数を返す。
int __stdcall get_blend_func_count()
{
    return 1;
}


//psdファイルに保存するときのkeyを返す。
/*
'norm' = normal
'dark' = darken
'lite' = lighten
'hue ' = hue
'sat ' = saturation
'colr' = color
'lum ' = luminosity
'mul ' = multiply
'scrn' = screen
'diss' = dissolve
'over' = overlay
'hLit' = hard light
'sLit' = soft light
'diff' = difference
'smud' = exlusion
'div ' = color dodge
'idiv' = color burn
*/
char* __stdcall get_blend_func_key(int no) 
{
	if (no == 0) {
		return "smud";
	}
	return 0;
}

//合成方法の名前を返す。
char* __stdcall get_blend_func_name(int no)
{
	if (no == 0) {
		return "除外";
	}
	return "";
}


//合成を行う関数。
//num_channel チャンネル数。グレーモードの場合は１、カラーモードの場合は３

void __stdcall blend(unsigned char* dst,const unsigned char* col,const unsigned char* alpha,int col_step,int alpha_step
					,int num_channel,int num_pixel,int no)
{
	if (no == 0) {//除外
// 計算サイト　http://www.tagen.tohoku.ac.jp/labo/ishijima/Photoshop-01.html
//  Overwrap = Bottom+Top-2*Bottom*Top/255

		if (num_channel == 1) { // 除外 グレスケ
			const unsigned char* col_end = col + num_pixel * col_step;
			while (col < col_end) {

				double d = 0;
				d = *dst + *col - 2 * *dst * *col/255 ;

					*dst = (d * *alpha/255.00) + (*dst * (1.00-*alpha/255.00))+0.5;

				alpha += alpha_step;
				col += col_step;
				dst += col_step;
			}
		}
		else if (num_channel == 3) { // 除外 カラー
			const unsigned char* col_end = col + num_pixel * col_step;
			while (col < col_end) {

				double d = 0;
				d = *dst + *col - 2 * *dst * *col/255 ;

				double d1 = 0;
				d1 = *(dst+1) + *(col+1) - 2 * *(dst+1) * *(col+1)/255 ;

				double d2 = 0;
				d2 = *(dst+2) + *(col+2) - 2 * *(dst+2) * *(col+2)/255 ;

				// レイヤーの色×不透明度　＋　下のレイヤーの色×(100％-不透明度)

					*dst = (d * *alpha/255.00) + (*dst * (1.00-*alpha/255.00))+0.5;
					*(dst + 1) = d1 * *alpha/255.00 + *(dst+1) * (1.00-*alpha/255.00)+0.5;
					*(dst + 2) = d2 * *alpha/255.00 + *(dst+2) * (1.00-*alpha/255.00)+0.5;


				alpha += alpha_step;
				col += col_step;
				dst += col_step;
			}
		}
	}
}

//下のレイヤーと結合で使用される
void __stdcall merge(n_byte* dst,const n_byte* col,const n_byte* base_col,const n_byte* alpha,const n_byte* base_alpha
					 ,int col_step,int alpha_step,int base_alpha_step,int num_channel,int num_pixel,int no)
{

	if (no == 0) {//除外
		if (num_channel == 1) {
			const unsigned char* col_end = col + num_pixel * col_step;
			while (col < col_end) {
				unsigned int a0 = *base_alpha;
				unsigned int a1 = *alpha;

				if (a1 != 0) {
				double d = 0;
				d = *dst + *col - 2 * *dst * *col/255 ;

				// 不透明度を入れた計算
				// Ca = 1-(1-Fa)*(1-Ba)
				//=( Fa *Ba * func(Bc,Fc) + Fa *(1-Ba) * Fc + (1-Fa)*Ba * Bc ) / Ca
				//http://www.greenwood.co.jp/~k-aki/article/pixel_composite.html

				double ca = 1 - (1- a1/255.0) * (1-a0/255.0) ;

					*dst = (a1/255.0 *(a0/255.0) * d + (a1/255.0) *(1-a0/255.0) * *col + (1-a1/255.0)*(a0/255.0) * *base_col ) / ca +0.5;

					*(dst + 1) = n_byte(((a0 + a1) * 255 - a0 * a1) / 255);	
				}
				else {
					*dst = *base_col;
					*(dst + 1) = *base_alpha;
				}

				dst += 2;
				col += col_step;
				base_col += col_step;
				alpha += alpha_step;
				base_alpha += alpha_step;
			}
		}
		else if (num_channel == 3) {
			const unsigned char* col_end = col + num_pixel * col_step;
			while (col < col_end) {
				unsigned int a0 = *base_alpha;
				unsigned int a1 = *alpha;

				if (a1 != 0) {
				
				double d = 0;
				d = *dst + *col - 2 * *dst * *col/255 ;
				double d1 = 0;
				d1 = *(dst+1) + *(col+1) - 2 * *(dst+1) * *(col+1)/255 ;
				double d2 = 0;
				d2 = *(dst+2) + *(col+2) - 2 * *(dst+2) * *(col+2)/255 ;

				// 不透明度を入れた計算
				// Ca = 1-(1-Fa)*(1-Ba)
				//=( Fa *Ba * func(Bc,Fc) + Fa *(1-Ba) * Fc + (1-Fa)*Ba * Bc ) / Ca
				//http://www.greenwood.co.jp/~k-aki/article/pixel_composite.html

				double ca = 1 - (1- a1/255.0) * (1-a0/255.0) ;

					*dst = (a1/255.0 *(a0/255.0) * d + (a1/255.0) *(1-a0/255.0) * *col + (1-a1/255.0)*(a0/255.0) * *base_col ) / ca +0.5;
					*(dst + 1) = (a1/255.0 *(a0/255.0) * d1 + (a1/255.0) *(1-a0/255.0) * *(col+1) + (1-a1/255.0)*(a0/255.0) * *(base_col+1) ) / ca +0.5;
					*(dst + 2) = (a1/255.0 *(a0/255.0) * d2 + (a1/255.0) *(1-a0/255.0) * *(col+2) + (1-a1/255.0)*(a0/255.0) * *(base_col+2) ) / ca +0.5;

					*(dst + 3) = n_byte(((a0 + a1) * 255 - a0 * a1) / 255);	
				}
				else {
					*dst = *base_col;
					*(dst + 1) = *(base_col + 1);
					*(dst + 2) = *(base_col + 2);
					*(dst + 3) = *base_alpha;
				}

				dst += 4;
				col += col_step;
				base_col += col_step;
				alpha += alpha_step;
				base_alpha += base_alpha_step;
			}
		}
	}
	
}




}
BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
					 )
{
    return TRUE;
}

#ifdef _MANAGED
#pragma managed(pop)
#endif