// ■任意の四角形内に画像を描く
#include "myView.h"
static myBitmap txt;static int edFlag=false;
void drawImage(double X1, double Y1, double X2, double Y2, double X3, double Y3, double X4, double Y4){
	int iw=txt.b.bmWidth, ih=txt.b.bmHeight; HDC hdctx =startBitmap(txt);
	double w=(double)iw, h=(double)ih;
	double sDY1=Y3-Y1, sDY2=Y4-Y2, sDX1=X3-X1, sDX2=X4-X2, ST=abs(sDY1);
	if(abs(sDY2)>ST)ST=abs(sDY2);
	if(abs(sDX1)>ST)ST=abs(sDX1);
	if(abs(sDX2)>ST)ST=abs(sDX2);
	ST*=2;sDY1/=ST; sDY2/=ST; sDX1/=ST; sDX2/=ST;
	double YY1=Y1, YY2=Y2, XX1=X1, XX2=X2;
	int jed=(int)(ST+0.5);
	for(int j=0; j<jed; j++, YY1+=sDY1, YY2+=sDY2, XX1+=sDX1, XX2+=sDX2){
		int py=(int)((double)j*h/ST);
		double DX=XX2-XX1, DY=YY2-YY1, ST2=abs(DX);if(abs(DY)>ST2)ST2=abs(DY);
		ST2*=2; DX/=ST2; DY/=ST2; int ked=(int)(ST2+0.5); double X=XX1,Y=YY1;
		for(int k=0; k<ked; k++,X+=DX, Y+=DY ){
			int px=(int)((double)k*w/ST2), C=GetPixel(hdctx, px, py); 
			SetPixel(hbuf,(int)(X), (int)(Y), C);
		}
	}
} 
//-----------------------------------------------------------------------------------------
void initBitMap(HWND hw){// ビットマップ作成とメモリデバイスコンテキスト作成
	createBitmap(hw); clearBitmap();
	windowSize(hw,700,450);
}
void procCreate(HWND hw, WPARAM wp, LPARAM lp){
	initBitMap(hw);	windowSize(hw,400,400);
	SetWindowText(hw,TEXT("任意の四角形に画像を描く"));
	txt=createMyBitmap(hw, TEXT("suzume"));
	drawImage(200, 50, 350, 150, 50,200,300,300);
	InvalidateRect(hw, NULL, TRUE);
	edFlag=true;
}
void procPaint(HWND hw, WPARAM wp, LPARAM lp){//ビットマップを画面に表示
	PAINTSTRUCT ps; HDC hdc=BeginPaint(hw, &ps);
	BitBlt(hdc,10,10,490,390,hbuf,0,0,SRCCOPY);
	EndPaint(hw,&ps);
}

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);
}