screensaver.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

/*
 *  Copyright 2003 J Brown
 *  Copyright 2006 Eric Kohl
 *  Copyright 2007 Marc Piulachs ([e-mail])
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include <windows.h>
#include <tchar.h>
#include "resource.h"

#define RANDOM( min, max ) ((rand() % (int)(((max)+1) - (min))) + (min))

#define MAX_LOADSTRING 100
#define MAX_STARS 1000

#define APPNAME				_T("Starfield")
#define APP_TIMER			1
#define APP_TIMER_INTERVAL	20

#define MAX_STARS 1000

// Details of each individual star
typedef struct star
{
	int m_nXPos, m_nYPos, m_nZPos;
	int m_nOldX, m_nOldY;
} STAR;

HINSTANCE hInstance;
BOOL fullscreen = FALSE;

STAR *stars;

int		m_nTotStars;
int		m_nCenterX, m_nCenterY;

void DrawStarField (HDC pDC)
{
	int nX, nY;
	int i;
	for (i = 0; i < m_nTotStars; i++)
	{
		//	Clear last position of this star
		SetPixel (
			pDC, 
			stars[i].m_nOldX, 
			stars[i].m_nOldY, 
			RGB (0, 0, 0));

		nX = (int)((((long)stars[i].m_nXPos << 7) / (long)stars[i].m_nZPos) + m_nCenterX);
		nY = (int)((((long)stars[i].m_nYPos << 7) / (long)stars[i].m_nZPos) + m_nCenterY);
		
		// Draw star
		SetPixel (
			pDC, 
			nX, 
			nY, 
			RGB (255, 255, 255));
		
		// Remember current position for clearing later
		stars[i].m_nOldX = nX;
		stars[i].m_nOldY = nY;
	}
}

BOOL SetUpStars (int nNumStars)
{
	int i;
	if (nNumStars > MAX_STARS)
	{
		MessageBox (0, 
			_T("Too many stars! Aborting!"), 
			_T("Error"), 
			MB_OK | MB_ICONWARNING);
		return FALSE;
	}

	if (stars)
		free (stars);

	m_nTotStars = nNumStars;

	stars = (STAR*)malloc(nNumStars * sizeof(STAR));

	if (!stars)
	{
		MessageBox (0,
			_T("Unable to allocate memory! Aborting!"), 
			_T("Error"), 
			MB_OK | MB_ICONWARNING);
		return FALSE;
	}

	for (i = 0; i < m_nTotStars; i++)
	{
		do
		{
			stars[i].m_nXPos = RANDOM (-320, 320);
			stars[i].m_nYPos = RANDOM (-200, 200);
			stars[i].m_nZPos = i+1;
			stars[i].m_nOldX = -1;
			stars[i].m_nOldY = -1;
		} while ((stars[i].m_nXPos == 0) || (stars[i].m_nYPos == 0));
	}
	
	return TRUE;
}

void MoveStarField (int nXofs, int nYofs, int nZofs)
{
	int i;
	for (i = 0; i < m_nTotStars; i++)
	{
		stars[i].m_nXPos += nXofs;
		stars[i].m_nYPos += nYofs;
		stars[i].m_nZPos += nZofs;

		if (stars[i].m_nZPos > m_nTotStars)
			stars[i].m_nZPos -= m_nTotStars;
		if (stars[i].m_nZPos < 1)
			stars[i].m_nZPos += m_nTotStars;
	}
}

void SetDimensions (int nWidth, int nHeight)
{
	m_nCenterX = nWidth / 2;
	m_nCenterY = nHeight / 2;
}

LRESULT WINAPI WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	static POINT ptLast;
	static POINT ptCursor;
	static BOOL  fFirstTime = TRUE;
	static HDC pDC;

	switch (msg)
	{
		case WM_CREATE :
		{
			SetTimer (
				hwnd, 
				APP_TIMER, 
				APP_TIMER_INTERVAL, 
				NULL);
		}
		break;
		case WM_PAINT :
		{
			PAINTSTRUCT	PtStr;
			HDC pDC = BeginPaint (hwnd, &PtStr);
			DrawStarField (pDC);
			EndPaint (hwnd, &PtStr);
			return (0);
		}
		break;
		case WM_TIMER :
		{
			if (wParam == APP_TIMER)
			{
				MoveStarField (0, 0, -3);
				pDC = GetDC(hwnd);
				DrawStarField (pDC);
				ReleaseDC(hwnd, pDC);
			}
		}
		break;
		case WM_SIZE :
		{
			//	Change the center point of the starfield
			SetDimensions (
				LOWORD(lParam), 
				HIWORD(lParam));
		}
		break;
		case WM_DESTROY :
		{
			KillTimer (hwnd, APP_TIMER);
			free(stars);
			PostQuitMessage (0);
			return 0;
		}
		break;
		// break out of screen-saver if any keyboard activity
		case WM_NOTIFY:
		case WM_SYSKEYDOWN:
		{
			PostMessage(hwnd, WM_CLOSE, 0, 0);
			break;
		}
		// break out of screen-saver if any mouse activity
		case WM_LBUTTONDOWN:
		case WM_LBUTTONUP:
		case WM_RBUTTONDOWN:
		case WM_RBUTTONUP:
		case WM_MBUTTONDOWN:
		case WM_MBUTTONUP:
		case WM_MOUSEMOVE:
		{
			// If we've got a parent then we must be a preview
			if(GetParent(hwnd) != 0)
				return 0;

			if(fFirstTime)
			{
				GetCursorPos(&ptLast);
				fFirstTime = FALSE;
			}

			GetCursorPos(&ptCursor);

			// if the mouse has moved more than 3 pixels then exit
			if( (abs(ptCursor.x - ptLast.x) >= 3) || 
				(abs(ptCursor.y - ptLast.y) >= 3))
			{
				PostMessage(hwnd, WM_CLOSE, 0, 0);
			}

			ptLast = ptCursor;
			return 0;
		}
	}

	return DefWindowProc(hwnd, msg, wParam, lParam);
}


void InitSaver(HWND hwndParent)
{
	WNDCLASS wc;
	ZeroMemory(&wc, sizeof(wc));
	wc.style            = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc      = WndProc;
	wc.lpszClassName    = APPNAME;
	wc.hbrBackground    = (HBRUSH)GetStockObject(BLACK_BRUSH);
	RegisterClass(&wc);

	if (hwndParent != 0)
	{
		RECT rect;
		GetClientRect(hwndParent, &rect);
		CreateWindow(APPNAME, APPNAME,
		             WS_VISIBLE | WS_CHILD,
		             0, 0,
		             rect.right,
		             rect.bottom,
		             hwndParent, 0,
		             hInstance, NULL);
		fullscreen = FALSE;
	}
	else
	{
		HWND hwnd;
		hwnd = CreateWindow(APPNAME, APPNAME,
		                    WS_VISIBLE | WS_POPUP | WS_EX_TOPMOST,
		                    0, 0,
		                    GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN),
		                    HWND_DESKTOP, 0,
		                    hInstance, NULL);
		ShowWindow(hwnd, SW_SHOWMAXIMIZED);
		ShowCursor(FALSE);
		fullscreen = TRUE;
	}

    SetUpStars(250);
}

void ParseCommandLine(PSTR szCmdLine, int *chOption, HWND *hwndParent)
{
	int ch = *szCmdLine++;

	if(ch == '-' || ch == '/')
		ch = *szCmdLine++;

	if(ch >= 'A' && ch <= 'Z')
		ch += 'a' - 'A';

	*chOption = ch;
	ch = *szCmdLine++;

	if(ch == ':')
		ch = *szCmdLine++;

	while(ch == ' ' || ch == '\t')
		ch = *szCmdLine++;

	if(isdigit(ch))
	{
		unsigned int i = atoi(szCmdLine - 1);
		*hwndParent = (HWND)i;
	}
	else
		*hwndParent = 0;
}

int WINAPI WinMain (HINSTANCE hInst,
                    HINSTANCE hPrev,
                    LPSTR lpCmdLine,
                    int iCmdShow)
{
	HWND	hwndParent;
	UINT	nPreviousState;
	int	chOption;
	MSG	Message;

	hInstance = hInst;

	ParseCommandLine(lpCmdLine, &chOption, &hwndParent);

	SystemParametersInfo(SPI_SETSCREENSAVERRUNNING, TRUE, &nPreviousState, 0);

	switch (chOption)
	{
		case 's':
			InitSaver(0);
			break;

		case 'p':
			InitSaver(hwndParent);
			break;

		case 'c':
		default:
			MessageBox(0,
			           _T("No options need to be set."),
			           _T("About"),
			           MB_OK | MB_ICONWARNING);
			return 0;
	}

	while (GetMessage(&Message, 0, 0, 0))
		DispatchMessage(&Message);

	SystemParametersInfo(SPI_SETSCREENSAVERRUNNING, FALSE, &nPreviousState, 0);

	return Message.wParam;
}