桌面下雪小程序

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); 
      } 
  } 
}