使用win32模式编译.

//#include "stdafx.h"
#include   
#include   
#include  
//#pragma comment(/Entry:WinMain)
#define ID_TIMER    1  
#define SNOWNUM      500  // 雪花数量  
#define CONTRAST    50    // 对比度  
#define YSTART      5    // 用于确定雪花初始时的y坐标  
#define SNOWCR      RGB(0xFF, 0xFF, 0xFF) //雪花的颜色—白色  
#define SNOWGATHERCR RGB(0xDB, 0xDB, 0xFF) //堆积雪花的颜色  typedef struct tagSnow 
{ POINT ptSnowsPos[SNOWNUM]; //用于保存各个雪花的坐标  COLORREF crOrg[SNOWNUM]; //用于画雪花前屏幕原来的颜色  int iVx, iVy, iAllVx, iAllVy; 
}Snow; void initSnow(HDC hdc, Snow *sn, int iSnow, int cxScreen); 
int GetContrast(HDC hdc, Snow *sn, int iSnow); 
void drawSnow(HDC hdc, Snow *sn, int cxScreen); LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) 
{ static TCHAR szAppName[] = TEXT ("clsDeskSnow") ; HWND            hwnd ; MSG            msg ; WNDCLASS    wndclass ; wndclass.style        = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc  = WndProc ; wndclass.cbClsExtra    = 0 ; wndclass.cbWndExtra    = 0 ; wndclass.hInstance    = hInstance ; wndclass.hIcon        = LoadIcon (NULL, IDI_APPLICATION) ; wndclass.hCursor      = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ; wndclass.lpszMenuName  = NULL ; wndclass.lpszClassName = szAppName ; if(!RegisterClass (&wndclass)) { MessageBox (NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0; } hwnd = CreateWindow (szAppName,        TEXT ("桌面下雪"), WS_MINIMIZEBOX | WS_SYSMENU, CW_USEDEFAULT, CW_USEDEFAULT, 240, 120, NULL, NULL, hInstance, NULL) ; ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; 
} LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) 
{ HDC          hdc ; PAINTSTRUCT  ps ; RECT        rect ; static int cxScreen, cyScreen; //屏幕宽高度(单位:像素)  static int iTimes, iLoopTimes=100; static Snow snowDream; int i; switch (message) { case WM_CREATE: cxScreen = GetSystemMetrics (SM_CXSCREEN) ; cyScreen = GetSystemMetrics (SM_CYSCREEN) ; srand ((int) GetCurrentTime ()) ; //初始化随机数发生器  snowDream.iAllVx = (unsigned)rand()%3 - 1; //雪花总体水平飘行速度(-1,0,1)  snowDream.iAllVy = (unsigned)rand()%2 + 1; //雪花总体垂直下落速度(1,2)  hdc = GetDC(NULL); //检索整个屏幕的设备上下文环境  for(i=0; i  iLoopTimes) { iTimes = 0; iLoopTimes = 50 + (unsigned)rand()%50; if(snowDream.iAllVx != 0) snowDream.iAllVx = 0; else                  snowDream.iAllVx = (unsigned)rand()%3 - 1; //雪花总体水平飘行速度(-1,0,1)  snowDream.iAllVy = (unsigned)rand()%2 + 1; //雪花总体垂直下落速度(1,2)  } else iTimes++; drawSnow(hdc, &snowDream, cxScreen); ReleaseDC(NULL, hdc); return 0; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; GetClientRect (hwnd, &rect) ; DrawText (hdc, TEXT ("桌面下雪!"), -1, &rect, DT_SINGLELINE | DT_CENTER | DT_VCENTER) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_DESTROY: KillTimer(hwnd, ID_TIMER); // 中止定时器  InvalidateRect(NULL, NULL, TRUE); // 刷新桌面  PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; 
} void initSnow(HDC hdc, Snow *sn, int iSnow, int cxScreen) //初始化第iSnow个雪花  
{ sn->ptSnowsPos[iSnow].x = (unsigned)rand() % cxScreen; //x范围整个屏幕宽  sn->ptSnowsPos[iSnow].y = (unsigned)rand() % YSTART; //y范围离屏幕顶部YSTART像素点以内  sn->crOrg[iSnow] = GetPixel(hdc, sn->ptSnowsPos[iSnow].x, sn->ptSnowsPos[iSnow].y ) ;//获取给定点的原来的颜色值  
} int GetContrast(HDC hdc, Snow *sn, int iSnow) 
{ int iR, iG, iB; COLORREF crCmp; if(0 == sn->iVx) //若水平速度为0，则取比其大一个像素的正下方的点  crCmp = GetPixel(hdc, sn->ptSnowsPos[iSnow].x, sn->ptSnowsPos[iSnow].y + 1); else //若水平速度>0，取右下方的点。 <0则取左下方的点  crCmp = GetPixel(hdc, sn->ptSnowsPos[iSnow].x + (sn->iVx>0?1:-1), sn->ptSnowsPos[iSnow].y + 1); if(crCmp==SNOWCR) //如果为雪花的颜色  return 0; //分别获取crCmp与对比点的蓝、绿、红部分的差值  iB = abs((crCmp>>16)&0xFF - (sn->crOrg[iSnow]>>16)&0xFF); iG = abs((crCmp>>8)&0xFF  - (sn->crOrg[iSnow]>>8)&0xFF); iR = abs((crCmp)&0xFF    - (sn->crOrg[iSnow])&0xFF); return (iR+iG+iB)/3; 
} void drawSnow(HDC hdc, Snow *sn, int cxScreen) 
{ int i; for(i=0; i crOrg[i] != SNOWCR) SetPixel(hdc, sn->ptSnowsPos[i].x, sn->ptSnowsPos[i].y, sn->crOrg[i]); //还原上一个位置的颜色  sn->iVx = sn->iAllVx*(i%3+1); //雪花的x飘动速度  sn->iVy = sn->iAllVy*(i%3+1); //雪花的y飘动速度  //rand()%5-2使雪花下落的时候 有抖动效果  sn->ptSnowsPos[i].x += sn->iVx+rand()%5-2; //雪花的下一个x坐标  sn->ptSnowsPos[i].y += sn->iVy+1; //雪花的下一个y坐标  //获取给定点的原来的颜色值  sn->crOrg[i] = GetPixel(hdc, sn->ptSnowsPos[i].x, sn->ptSnowsPos[i].y); if(CLR_INVALID == sn->crOrg[i]) //如果获取颜色失败,即雪花飘出了屏幕  { initSnow(hdc, sn, i, cxScreen); //重新初始化 雪花  continue; } if(sn->crOrg[i] != SNOWCR) //若当前点的颜色 不等于 雪花的颜色  { if(SNOWGATHERCR == sn->crOrg[i]) //当前点的颜色=堆积的雪的颜色  {  //设置为雪花的颜色  SetPixel(hdc, sn->ptSnowsPos[i].x, sn->ptSnowsPos[i].y, SNOWCR); sn->crOrg[i] = SNOWCR; //initSnow(hdc, sn, i, cxScreen); //重新初始化 雪花  } else if(GetContrast(hdc, sn, i) > 50) //若对比度>50  {  //堆积雪花  SetPixel(hdc, sn->ptSnowsPos[i].x,  sn->ptSnowsPos[i].y,  SNOWGATHERCR); SetPixel(hdc, sn->ptSnowsPos[i].x-1, sn->ptSnowsPos[i].y+1, SNOWGATHERCR); SetPixel(hdc, sn->ptSnowsPos[i].x+1, sn->ptSnowsPos[i].y+1, SNOWGATHERCR); initSnow(hdc, sn, i, cxScreen); //重新初始化 雪花  } else //对比度 <50,不堆积,画出这帧雪花.等下次的时候再还原此点原本的颜色.以产生飘动效果  SetPixel(hdc, sn->ptSnowsPos[i].x, sn->ptSnowsPos[i].y, SNOWCR); } } 
}