drawline1.cpp

一个简单的画直线的程序 用的是中心线算法画的

// DrawLine1.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "resource.h"

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;								// current instance
TCHAR szTitle[MAX_LOADSTRING];								// The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];							// The title bar text
bool isFirst = true;
POINT fPoint,lPoint;

// Foward declarations of functions included in this code module:
ATOM				MyRegisterClass(HINSTANCE hInstance);
BOOL				InitInstance(HINSTANCE, int);
LRESULT CALLBACK	WndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK	About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
 	// TODO: Place code here.
	MSG msg;
	HACCEL hAccelTable;

	// Initialize global strings
	LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
	LoadString(hInstance, IDC_DRAWLINE1, szWindowClass, MAX_LOADSTRING);
	MyRegisterClass(hInstance);

	// Perform application initialization:
	if (!InitInstance (hInstance, nCmdShow)) 
	{
		return FALSE;
	}

	hAccelTable = LoadAccelerators(hInstance, (LPCTSTR)IDC_DRAWLINE1);

	// Main message loop:
	while (GetMessage(&msg, NULL, 0, 0)) 
	{
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) 
		{
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
	}

	return msg.wParam;
}


void DrawLine(HDC hdc,POINT apt)
{
	if(fPoint.x > apt.x)
	{
		lPoint.x = fPoint.x;
		lPoint.y = fPoint.y;
		fPoint.x = apt.x;
		fPoint.y = apt.y;
	}
	else
	{
		lPoint.x = apt.x;
		lPoint.y = apt.y;
	}
	float k;
	k = (float)(lPoint.y - fPoint.y)/(lPoint.x - fPoint.x);
	POINT dPoint = fPoint;
	if(k>=0&&k<=1)
	{
		SetPixel(hdc,dPoint.x,dPoint.y,RGB(0,0,0));
		for(int t = 1; t<=(lPoint.x - fPoint.x);t++)
		{
			dPoint.x++;
			if((fPoint.y+t*k) > (dPoint.y + 0.5))
				dPoint.y++;
			SetPixel(hdc,dPoint.x,dPoint.y,RGB(0,0,0));
		}
	}
	if(k>1)
	{
		POINT fTempPoint,lTempPoint;
		fTempPoint.x = fPoint.y;
		fTempPoint.y = fPoint.x;
		lTempPoint.x = lPoint.y;
		lTempPoint.y = lPoint.x;
		dPoint = fTempPoint;
		float g = 1/k;
		SetPixel(hdc,fTempPoint.y,fTempPoint.x,RGB(0,0,0));
		for(int t = 1; t<=(lTempPoint.x - fTempPoint.x);t++)
		{
			dPoint.x++;
			if((fTempPoint.y+t*g) > (dPoint.y + 0.5))
				dPoint.y++;
			SetPixel(hdc,dPoint.y,dPoint.x,RGB(0,0,0));
		}
	}
	if(k<0 && k>= -1)
	{
		
		SetPixel(hdc,dPoint.x,dPoint.y,RGB(0,0,0));
		for(int t = 1; t<=(lPoint.x - fPoint.x);t++)
		{
			dPoint.x++;
			if((fPoint.y+t*k) < (dPoint.y - 0.5))
				dPoint.y--;
			SetPixel(hdc,dPoint.x,dPoint.y,RGB(0,0,0));
		}
	}
	if(k<-1)
	{
		
		POINT fTempPoint,lTempPoint;
		fTempPoint.x = lPoint.y;
		fTempPoint.y = lPoint.x;
		lTempPoint.x = fPoint.y;
		lTempPoint.y = fPoint.x;
		dPoint = fTempPoint;
		float g = 1/k;
		SetPixel(hdc,fTempPoint.y,fTempPoint.x,RGB(0,0,0));
		for(int t = 1; t<=(lTempPoint.x - fTempPoint.x);t++)
		{
			dPoint.x++;
			if((fTempPoint.y+t*g) < (dPoint.y - 0.5))
				dPoint.y--;
			SetPixel(hdc,dPoint.y,dPoint.x,RGB(0,0,0));
		}
	}
}


//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
//  COMMENTS:
//
//    This function and its usage is only necessary if you want this code
//    to be compatible with Win32 systems prior to the 'RegisterClassEx'
//    function that was added to Windows 95. It is important to call this function
//    so that the application will get 'well formed' small icons associated
//    with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
	WNDCLASSEX wcex;

	wcex.cbSize = sizeof(WNDCLASSEX); 

	wcex.style			= CS_HREDRAW | CS_VREDRAW;
	wcex.lpfnWndProc	= (WNDPROC)WndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= hInstance;
	wcex.hIcon			= LoadIcon(hInstance, (LPCTSTR)IDI_DRAWLINE1);
	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);
	wcex.lpszMenuName	= (LPCSTR)IDC_DRAWLINE1;
	wcex.lpszClassName	= szWindowClass;
	wcex.hIconSm		= LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);

	return RegisterClassEx(&wcex);
}

//
//   FUNCTION: InitInstance(HANDLE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  FUNCTION: WndProc(HWND, unsigned, WORD, LONG)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND	- process the application menu
//  WM_PAINT	- Paint the main window
//  WM_DESTROY	- post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static POINT apt;
	int wmId, wmEvent;
	PAINTSTRUCT ps;
	HDC hdc;
	TCHAR szHello[MAX_LOADSTRING];
	LoadString(hInst, IDS_HELLO, szHello, MAX_LOADSTRING);

	switch (message) 
	{
		case WM_COMMAND:
			wmId    = LOWORD(wParam); 
			wmEvent = HIWORD(wParam); 
			// Parse the menu selections:
			switch (wmId)
			{
				case IDM_ABOUT:
				   DialogBox(hInst, (LPCTSTR)IDD_ABOUTBOX, hWnd, (DLGPROC)About);
				   break;
				case IDM_EXIT:
				   DestroyWindow(hWnd);
				   break;
				default:
				   return DefWindowProc(hWnd, message, wParam, lParam);
			}
			break;
		case WM_PAINT:
			ValidateRect(hWnd,NULL);
			break;
		case WM_DESTROY:
			PostQuitMessage(0);
			break;
		case WM_LBUTTONDOWN:
			if(isFirst == true)
			{
				fPoint.x = LOWORD(lParam);
				fPoint.y = HIWORD(lParam);
				isFirst = false;
			}
			else
			{
				hdc = GetDC(hWnd);
				apt.x = LOWORD(lParam);
				apt.y = HIWORD(lParam);
				DrawLine(hdc,apt);
				ReleaseDC(hWnd,hdc);
				isFirst = true;
			}
			break;
		/*case WM_MOUSEMOVE:
			if(wParam &MK_LBUTTON)
			{
				hdc = GetDC(hWnd);
				SelectObject(hdc,GetStockObject(WHITE_PEN));
				DrawLine(hdc,apt);
				apt.x = LOWORD(lParam);
				apt.y = LOWORD(lParam);
				SelectObject(hdc,GetStockObject(BLACK_PEN));
				DrawLine(hdc,apt);
				ReleaseDC(hWnd,hdc);
			}
			break;*/
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}

// Mesage handler for about box.
LRESULT CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)
	{
		case WM_INITDIALOG:
				return TRUE;

		case WM_COMMAND:
			if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) 
			{
				EndDialog(hDlg, LOWORD(wParam));
				return TRUE;
			}
			break;
	}
    return FALSE;
}