#include "windows.h"
#include "cmath"
#include "windowsx.h"
#include "tchar.h"
#include "iostream"


LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
#define defwidth 640
#define defheight 480
int WINAPI WinMain(HINSTANCE hInst,HINSTANCE Hst,LPSTR str,int mode)
{
	TCHAR* szClassName = _T("MyWindClass");
	TCHAR* szWinName = _T("Math");
	MSG msg;
	WNDCLASS wnc;
	ZeroMemory(&wnc,sizeof wnc);
	wnc.lpfnWndProc = WndProc;
	wnc.hInstance = hInst;
	wnc.lpszClassName = szClassName;
	wnc.hIcon = LoadIcon(NULL,IDI_APPLICATION);
	wnc.hCursor = LoadCursor(NULL,IDC_ARROW);
	wnc.hbrBackground = CreateSolidBrush(RGB(255,255,255));
	RegisterClass(&wnc);
	HWND hwnd = CreateWindow(
		szClassName,
		szWinName,
		WS_SYSMENU,
		10,
		10,
		defwidth,
		defheight,
		HWND_DESKTOP,
		NULL,
		hInst,
		NULL
		);
	ShowWindow(hwnd,SW_SHOWDEFAULT);
	while(GetMessage(&msg,NULL,0,0))
		DispatchMessage(&msg);
}

void OnDestroy(HWND);
void OnPaint(HWND);
BOOL OnCreate(HWND,LPCREATESTRUCT);

LRESULT CALLBACK WndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam)
{
	switch(msg)
	{
		HANDLE_MSG(hwnd,WM_DESTROY,OnDestroy);
		HANDLE_MSG(hwnd,WM_PAINT,OnPaint);
		HANDLE_MSG(hwnd,WM_CREATE,OnCreate);
	default:
		return DefWindowProc(hwnd,msg,wParam,lParam);
	}
}

void _stdcall TiMe(HWND hwnd, UINT uMsg, UINT_PTR idEvent, DWORD dwTime)
{
	InvalidateRect(hwnd,NULL,true);
}

BOOL OnCreate(HWND hw,LPCREATESTRUCT)
{
	return true;
}

void OnDestroy(HWND)
{
	PostQuitMessage(1);
}

#define LN2 0.69314718055994530942;
#define PI 3.141592653589793;

inline double getFuncY(long double x)
{
	if(x < -3)
		return 3*x + 7;
	else if(x >= -3 && x <= 3)
		return -2;
	else if(x > 3)
		return 3*x-11;
}

void OnPaint(HWND hw)
{
	PAINTSTRUCT ps;
	RECT rect;
	GetClientRect(hw,&rect);
	int xaxis = rect.right/2,yaxis = rect.bottom/2;
	HDC hdc = BeginPaint(hw,&ps);
	SelectBrush(hdc,CreateSolidBrush(RGB(0,0,0)));
	MoveToEx(hdc,0,yaxis,NULL);
	LineTo(hdc,rect.right,yaxis);
	MoveToEx(hdc,xaxis,0,NULL);
	LineTo(hdc,xaxis,rect.bottom);
	MoveToEx(hdc,0,0,NULL);
	for(register double x = -100.0,y=0;x < 100.0;x+=0.01){
		y = -(getFuncY(x));
		int mn = 51;
		SetPixel(hdc,xaxis+x*mn,yaxis+y*mn,RGB(0,0,0));
	}
	EndPaint(hw,&ps);
}