return RegisterClassEx(&wcex);
}

//****初始化函数*************************************
// 1.加载位图资源
// 2.取得内部窗口区域信息
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
HBITMAP bmp;
hInst = hInstance;

hWnd = CreateWindow("maple", "浅墨的绘图窗口" , WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

if (!hWnd)
{
return FALSE;
}

MoveWindow(hWnd,10,10,600,450,true);
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);

hdc = GetDC(hWnd);
mdc = CreateCompatibleDC(hdc);

bufdc = CreateCompatibleDC(hdc);
bmp = CreateCompatibleBitmap(hdc,640,480);

SelectObject(mdc,bmp);

bg = (HBITMAP)LoadImage(NULL,"bg.bmp",IMAGE_BITMAP,rect.right,rect.bottom,LR_LOADFROMFILE);
snow = (HBITMAP)LoadImage(NULL,"snow.bmp",IMAGE_BITMAP,20,20,LR_LOADFROMFILE);
mask = (HBITMAP)LoadImage(NULL,"mask.bmp",IMAGE_BITMAP,20,20,LR_LOADFROMFILE);
GetClientRect(hWnd,&rect);

SetTimer(hWnd,1,0,NULL);

MyPaint(hdc);

return TRUE;
}

//****自定义绘图函数*********************************
// 1.窗口贴图
// 2.实现雪花纷飞的效果
void MyPaint(HDC hdc)
{

//创建粒子
if(count<50) //当粒子数小于50时，产生新的粒子，设定每个粒子的属性值
{
drop[count].x = rand()%rect.right; //将粒子的X坐标设为窗口中水平方向上的任意位置
drop[count].y = 0; //将每个粒子的Y坐标都设为"0"，即从窗口上沿往下落
drop[count].exist = true; //设定粒子存在
count++; //每产生一个粒子后进行累加计数
}

//贴上背景图到mdc中
SelectObject(bufdc,bg);
BitBlt(mdc,0,0,640,480,bufdc,0,0,SRCCOPY);

//首先判断粒子是否存在，若存在，进行透明贴图操作
for(i=0;i<50;i++)
{

Sleep(1);
if(drop[i].exist)
{
SelectObject(bufdc,mask);
BitBlt(mdc,drop[i].x,drop[i].y,20,20,bufdc,0,0,SRCAND);

SelectObject(bufdc,snow);
BitBlt(mdc,drop[i].x,drop[i].y,20,20,bufdc,0,0,SRCPAINT);
if(rand()%2==0)
drop[i].x+=5;
else
drop[i].x-=5;
drop[i].y+=10;
if(drop[i].y > rect.bottom)
{
drop[i].x = rand()%rect.right;
drop[i].y = 0;
}
}

}

//将mdc中的全部内容贴到hdc中
BitBlt(hdc,0,0,640,480,mdc,0,0,SRCCOPY);

}

//****消息处理函数***********************************
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_TIMER: //时间消息
MyPaint(hdc); //在消息循环中加入处理WM_TIMER消息，当接收到此消息时便调用MyPaint（）函数进行窗口绘图
break;
case WM_KEYDOWN: //按键消息
if(wParam==VK_ESCAPE) //按下【Esc】键
PostQuitMessage(0);
break;
case WM_DESTROY: //窗口结束消息
DeleteDC(mdc);
DeleteDC(bufdc);
DeleteObject(bg);
DeleteObject(snow);
DeleteObject(mask);
KillTimer(hWnd,1); //窗口结束时，删除所建立的定时器
ReleaseDC(hWnd,hdc);
PostQuitMessage(0);
break;
default: //其他消息
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}

下面是运行后的截图效果：

作者：zhmxy555