#include "myWin.h"
#include "math.h"
#define BITMX 550
#define BITMY 450
static HDC hbuf; static HBITMAP hBM;
void clearBitmap(int width, int height){
	SelectObject(hbuf,GetStockObject(NULL_PEN));
	PatBlt(hbuf,0,0,width,height,WHITENESS);
}
void initBitmap(HWND hw, int width, int height){
	HDC hdc=GetDC(hw); hBM=CreateCompatibleBitmap(hdc,width,height);
	hbuf=CreateCompatibleDC(hdc);SelectObject(hbuf,hBM);
	ReleaseDC(hw, hdc);
}
double Gamma(double r){	// ガンマ関数
	if(abs(r) < 0.00001) return 1.7E+308; // r＝0 のとき発散
	if(r < 2 ){ // r<2のとき計算式を変える
		int n = 1000; double G = pow((double)n, r) / r;
		for(int k = 1; k<=n; k++) G *= (double)k / (r + (double)k);
		return G;
	}
    double DX = 0.1, s = 0,X1, X2 = 0, Y1, Y2, E1, E2 = exp(-X2);
	while(E2 > 0.000000000001){ //定義による積分
        E1 = E2; X1 = X2; X2 = X2 + DX; E2 = exp(-X2); Y1 = 0;
        if(X1 > 0.001 || r > 1 ) Y1 = E1 * pow(X1 , (r - 1));
        Y2 = E2 * pow(X2, (r - 1));
        s += (Y1 + Y2) * DX / 2;
	}
    return s;
}
void dspText(int X, int Y, TCHAR str[]){
	HFONT hf=CreateFont(8,0,0,0,FW_NORMAL,FALSE, FALSE, FALSE, SHIFTJIS_CHARSET,
		OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, DEFAULT_QUALITY,
		FIXED_PITCH|FF_MODERN, NULL); SelectObject(hbuf,hf);
	SetTextColor(hbuf,0); SetBkMode(hbuf,TRANSPARENT);
	TextOut(hbuf,X, Y ,str,lstrlen(str));  
}
double XST=20, YST=350,SCX=100, SCY=10;
void moveTo(double X1, double Y1){
	MoveToEx(hbuf,(int)(XST + X1 *SCX+0.5),(int)(YST - Y1 *SCY+0.5),NULL);
}
void lineTo(double X2, double Y2,int width, COLORREF C){
	HPEN hpen=CreatePen(PS_SOLID,width, C);
	SelectObject(hbuf,hpen);
	LineTo  (hbuf,(int)(XST + X2 *SCX+0.5),(int)(YST - Y2 *SCY+0.5));
	DeleteObject(hpen);
}
void drawLine(double X1, double Y1, double X2, double Y2,int width, COLORREF C){
	moveTo(X1,Y1);lineTo(X2,Y2,width,C);
}
void drawFrame(){
	int C;TCHAR str[256];
	for(int y=0;y<=30; y++){
		C=0xAAAAAA; 
		if(y%5==0) {
			C=0; wsprintf(str, TEXT("%2d"), y);
			dspText(8,(int)(YST-SCY*y-4),str);
		}
		drawLine(0.0, (double)y, 5, (double)y, 1, C);
	}
	double x=0;
	for(int i=0; i<=50; i++, x+=0.1){
		C=0xAAAAAA; 
		if(i%5==0) {
			C=0; 
			if(i%10==0){
				wsprintf(str, TEXT("%2d"), i/10);
				dspText((int)(XST+x*SCX-4),(int)YST+4,str);
			}
		}
		drawLine(x, 0, x, 30,  1, C);
	}
}
void drawGamma(){
	moveTo(0.04,Gamma(0.04));
	for(double r=0.05;r<=5; r+=0.01)lineTo(r, Gamma(r),2,0xFF);
}
void procPaint(HWND hw, WPARAM wp,LPARAM lp){
	PAINTSTRUCT ps; HDC hdc=BeginPaint(hw, &ps);
	BitBlt(hdc,0,0,BITMX,BITMY,hbuf,0,0,SRCCOPY);
	EndPaint(hw,&ps);
}
void procCreate(HWND hw, WPARAM wp,LPARAM lp){
	SetWindowText(hw,TEXT("Γ関数のグラフを描く"));
	MoveWindow(hw,0,0,BITMX,BITMY,TRUE); initBitmap(hw,BITMX,BITMY);
	clearBitmap(BITMX,BITMY);
	drawFrame();drawGamma(); InvalidateRect(hw,NULL,TRUE);

}
LRESULT CALLBACK WndProc(HWND hw, UINT msg, WPARAM wp,LPARAM lp){
	switch(msg){
	case WM_DESTROY    : PostQuitMessage(0)  ; return 0;
	case WM_CREATE     : procCreate(hw,wp,lp); return 0;
	case WM_PAINT      : procPaint(hw,wp,lp) ; return 0;
	}
	return DefWindowProc(hw,msg,wp,lp);
}