#include<windows.h>
#include<time.h>
#include<stdlib.h>

const SnowNumber=500; //雪點數量

struct SnowNode
{
POINT postion;  //雪點位置
int   iColor; //先前的顏色
int   iSpeed; //下落速度 
int   iMove; //下落距離
int   iStick; //粘貼度
};

SnowNode SnowNodes[SnowNumber]; //雪點數組
int   hTimer=0;
int   CrWind=0;
int   CrStep=0; //當前循環步數(用于限速)
int   ScreenWidth=0;  //屏幕寬度
int   ScreenHeight=0;  //屏幕高度

void GetScreenSize();
void CALLBACK TimerProc(HANDLE hWnd,UINT uMsg,UINT idEvent,DWORD dwTime);
void InitSnowNodes();
void MoveSnowNodes();

int WINAPI  WinMain(HINSTANCE hInstance,
       HINSTANCE hPrevInstance,
       LPSTR  lpCmdLine,
       int   nCmdShow
       )
{


MSG msg; //標準windows消息 
LARGE_INTEGER Frequency; //高性能定時器頻率
LARGE_INTEGER StartCt,EndCt;//高性能定時器計數
int ElapsedTime;      //時間間隔
srand((unsigned)time(NULL));
GetScreenSize();
InitSnowNodes();
QueryPerformanceFrequency(&Frequency);
hTimer=SetTimer(0,0,rand()%5*500,(TIMERPROC)TimerProc);
if(hTimer==0)
{
  MessageBox(0,TEXT("創建定時器失敗"),TEXT("提示"),MB_OK|MB_ICONINFORMATION);
  return -1;
}
RegisterHotKey(0,0,MOD_CONTROL,(int)'L');
while(1)
{
  QueryPerformanceCounter(&StartCt); //執行運算前計數值
  if(PeekMessage(&msg,0,0,0,1))
  {
   switch(msg.message)
   {
    case WM_TIMER: TimerProc(0,0,0,0);
        break; //預設風向改變時間已到
    case WM_HOTKEY: KillTimer(0,hTimer);//刪除隨機風向定時 器
        UnregisterHotKey(0,0);//刪除退出熱鍵
        InvalidateRect(0,NULL,true);
        exit(1);
        break;
    case WM_DISPLAYCHANGE:
        GetScreenSize(); //重新取屏幕的尺寸
        InitSnowNodes(); //初始化雪點的數組
        break;
   }

  }
  MoveSnowNodes();
  QueryPerformanceCounter(&EndCt);//執行運算后的計數值
  ElapsedTime=(EndCt.QuadPart-StartCt.QuadPart)/Frequency.QuadPart;
  if((ElapsedTime<0.0005))
   Sleep(2); //簡單限速
  else if(ElapsedTime<0.0010)
    Sleep(1);
    else if(ElapsedTime<0.0015)
     Sleep(3);

}
//MessageBox(0,TEXT("消息"),TEXT("消息"),MB_OK|MB_ICONINFORMATION);
return 0;
}
void GetScreenSize()
{
ScreenWidth=GetSystemMetrics(SM_CXSCREEN);
ScreenHeight=GetSystemMetrics(SM_CYSCREEN);
return ;
}

void CALLBACK TimerProc(HANDLE hWnd,UINT uMsg,UINT idEvent,DWORD dwTime)
{
// MessageBox(0,TEXT("消息"),TEXT("消息"),MB_OK|MB_ICONINFORMATION);
srand((unsigned)time(NULL));
if(hTimer==0)
{
  MessageBox(0,TEXT("創建定時器失敗"),TEXT("提示"),MB_OK|MB_ICONINFORMATION);
  return ;
}
SetTimer(0,hTimer,((rand()%27+4)*500),(TIMERPROC)TimerProc); //// 重設下次風向改變時間
//修改風向
if(CrWind!=0)
  CrWind=0;
else
     CrWind=rand()%3-1;
return ;
}

void InitSnowNodes()
{
HDC hScreenDC=0;
int j=0;
hScreenDC=CreateDC("DISPLAY",NULL,NULL,NULL);
  if(hScreenDC==NULL)
{
  MessageBox(0,"獲取屏幕DC失敗!","信息",MB_OK|MB_ICONERROR);
  return ;
}
srand((unsigned)time(NULL));
for(j=0;j<SnowNumber;j++)
{
  SnowNodes[j].postion.x=rand()%ScreenWidth;
  SnowNodes[j].postion.y=rand()%ScreenHeight;
  SnowNodes[j].iColor=GetPixel(hScreenDC,SnowNodes[j].postion.x,SnowNodes[j].postion.y);
  SnowNodes[j].iSpeed=(rand()%5+1);       //每次下落距離（1-5）
  SnowNodes[j].iStick=(30-rand()%SnowNodes[j].iSpeed); //粘貼度（幾次循環作一次粘貼連判斷
  
}
DeleteDC(hScreenDC);
}

void MoveSnowNodes()
{
// MessageBox(0,TEXT("消息"),TEXT("消息"),MB_OK|MB_ICONINFORMATION);
HDC hScreenDC=0;
srand((unsigned)time(NULL));
int x=0,y=0,i=0;
hScreenDC=CreateDC("DISPLAY",NULL,NULL,NULL);
if(hScreenDC==NULL)
{
  MessageBox(0,"獲取屏幕DC失敗!","信息",MB_OK|MB_ICONERROR);
  return ;
}
TextOut(hScreenDC,0,0,"雖然大檢查順順藤摸瓜克格勃呀加",0);
for(i=0;i<SnowNumber;i++)
{
  //控制雪點下降速度
  if((CrStep%SnowNodes[i].iSpeed)!=0)
   continue;
  //恢復上次被覆蓋點
  if((GetPixel(hScreenDC,SnowNodes[i].postion.x,SnowNodes[i].postion.y))==0XFFFFFF)
   SetPixel(hScreenDC,SnowNodes[i].postion.x,SnowNodes[i].postion.y,SnowNodes[i].iColor);
  //根據幾向作隨機飄落
  x=SnowNodes[i].postion.x+rand()%3+CrWind;
  y=SnowNodes[i].postion.y+SnowNodes[i].iMove;

  //積雪（停留）效果處理
  if(  ( (CrStep%SnowNodes[i].iStick)==0)
     &&( (GetPixel(hScreenDC,x,y))!=(GetPixel(hScreenDC,x,y+1)))
     &&( (GetPixel(hScreenDC,x-1,y))!=(GetPixel(hScreenDC,x-1,y+1)))
     &&( (GetPixel(hScreenDC,x+1,y))!=GetPixel(hScreenDC,x+1,y+1))
     )
  {
   //稍稍調整坐標
   if(GetPixel(hScreenDC,x,y-1)==GetPixel(hScreenDC,x,y-2))
   {
    y--;
   }
   else
   {
       if(GetPixel(hScreenDC,x,y-1)==GetPixel(hScreenDC,x,y-2))
     y++;
    x+=CrWind;
   }
   //畫三個雪花點
   SetPixel(hScreenDC,x,y,0XFFFFFF);
   SetPixel(hScreenDC,x+1,y+1,0XFFFFFF);
   SetPixel(hScreenDC,x-1,y-1,0XFFFFFF);
   //重生雪點
   SnowNodes[i].postion.x=rand()%ScreenWidth;
   SnowNodes[i].postion.y=rand()%10;
   SnowNodes[i].iColor=GetPixel(hScreenDC,SnowNodes[i].postion.x,SnowNodes[i].postion.y);
   
  }
  else
  {
   if( (x<0) || (x>ScreenWidth) || (y>ScreenHeight))
   {
    SnowNodes[i].postion.x=rand()%10;
    SnowNodes[i].postion.y=rand()%ScreenWidth;
    SnowNodes[i].iColor=GetPixel(hScreenDC,SnowNodes[i].postion.x,SnowNodes[i].postion.y);

   }
   else
   {
    //保存顏色并繪制雪點
    SnowNodes[i].iColor=GetPixel(hScreenDC,x,y);
    SetPixel(hScreenDC,x,y,0XFFFFFF);
    //此時保存新雪點位置
    SnowNodes[i].postion.x=x;
    SnowNodes[i].postion.y=y;
   }
  }
  DeleteDC(hScreenDC);
  CrStep++;
}
}