選択範囲の反転描画 - musaka @ ウィキ

void DrawSelect(HDC destDC,int fromX,int fromY, int toX, int toY)
{
	int tmpfromX,tmpfromY,tmptoX,tmptoY;
	if(toX>=fromX){
		tmpfromX=fromX; tmptoX=toX;
	}else{
		tmpfromX=toX; tmptoX=fromX;
	}
	if(toY>=fromY){
		tmpfromY=fromY; tmptoY=toY;
	}else{
		tmpfromY=toY; tmptoY=fromY;
	}
BitBlt(destDC,tmpfromX,tmpfromY,tmptoX-tmpfromX,tmptoY-tmpfromY,destDC,tmpfromX,tmpfromY,DSTINVERT);
}